Recent Advances in Immunopharmacology

Dr Aaditya

Immumopharmacology

Understanding Immunology

Modulating immune

response

Humoral Immune response

Polyclonal Abs Monoclonal Abs

Cell mediated immune response

Interleukins & other agents

Evaluating Immunological

Agents

Recent markers and parameters

Rules and regulations

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THE NORMAL IMMUNE RESPONSE

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Immunity Ability to resist almost all types of organisms or

toxins that tends to damage the tissues or organ.

Immunity

Innate Acquired

Active Passive08/04/2023 4Dr Aaditya

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T- Cell Activation

Signal I- MHC binding With TCR

Signal II- ligation of co-stimulatory molecule CD 40, CD80 with to CD 40L, CD 28 respectively

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T- Cell Activation

• Negative feed-back loop T-lymphocyte – associated antigen 4 (CTLA-4)

• Following binding of CD28 with CD80 or CD 86, CTLA-4 is mobilised to cell surface were because of its higher affinity for CD80, 86 it outcompetes or displaces CD 28 and results in suppression of T- cell activation & proliferation

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IPILIMUMAB

• Recombinant humanized antibody that binds CTLA- 4 and prevents its association with CD 80, 86.

• So, the activated state of T- cells is sustained• Tried in patients of Malignant Melanoma• Showed objective improvement in some• S/E development of autoimmune toxicity

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ABATACEPT• Recombinant fusion protein composed of the

extracellular domain of cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) fused to human IgG Fc

• This fusion protein blocks activation of T cells by binding to CD80 or 86 so that CD28 on T cells cannot bind and stimulate the T cell and lead to cytokine release

• Approved for patients with severe rheumatoid arthritis who have failed other DMARDS

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RECENT EVALUATION TECHNIQUES

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Anti Inflammatory Models

Receptor binding activity

Substance P

3H-Bradykinin

The Tachykinin Family

Neurokinin

Assays of Migration and aggregation

Polymorphonuclear leukocyte

chemotaxis

Cytokines

Flow cytometry

TNF antagonism

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Immuno-modulatory Activity

Proliferation of Cells

PFC (plaque forming colony)

Chemoluminescence in macrophages

Mitogen Induced Lymphocyte Proliferation

Autoimmune Response

CTLA-4 Knockout Mouse

Hypersensitivity in animals

Organ Transplant

Acute GVHD in rats

Inhibition of allogenic transplant

rejection

Influence on SLE-like disorder in MRL/lpr

mice

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MARKERS USED IN IMMUNOPHARMACOLOGY

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Traditional markers

• Total leukocyte count• Differential count• Neutrophil/Lymphocyte Ratio• T-cell CD4+/CD8+ Ratio• T-cell CD4+CD45RO+ expression• Plasma glutamine• Plasma urea• Salivary IgA08/04/2023 Dr Aaditya 15

Newer markers of immune response

• Plasma Cytokine levels– In fever, shock TNF, INF-γ, IL-1,2,6,10

• The soluble receptors of IL-2 (sIL-2R) and tumor necrosis factor (sTNF-R55 and sTNF-R75)– In suspected childhood maleria

• Serum levels of β2-microglobulin, neopterin– In HIV 1& 2 patients

• TNF, INF-γ, receptors of IL-2 (sIL-2R) etc– Used to determine chemotherapy regimen in

cancer08/04/2023 Dr Aaditya 16

AGENTS MODIFYING THE IMMUNE RESPONSE

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GLUCOCORTICOIDS• First hormonal agents recognized as having

lympholytic properties• Reduces the size and lymphoid content of the

lymph nodes and spleen• Contact hypersensitivity mediated by DTH T cells,

for example, is usually abrogated by glucocorticoid therapy

• Glucocorticoids are first-line immunosuppressive therapy for both solid organ and hematopoietic stem cell transplant recipients, with variable results

• Also used in variety of conditions like SLE, asthma 08/04/2023 18Dr Aaditya

IMMUNOPHILIN LIGANDS• Cyclosporine

– Peptide antibiotic early stage in the antigen receptor-induced differentiation of T cells and blocks their activation

– Binds to cyclophilin (a class of intracellular proteins called immunophilins)

– Inhibits the cytoplasmic phosphatase, calcineurin, which is necessary for the activation of a T-cell-specific transcription factor

– This transcription factor, NF-AT, is involved in the synthesis of interleukins (eg, IL-2) by activated T cells

– Cyclosporine inhibits the gene transcription of IL-2, IL-3, IFN-g08/04/2023 19Dr Aaditya

IMMUNOPHILIN LIGANDS• Tacrolimus

– It is not chemically related to cyclosporine, but their mechanisms of action are similar

– Tacrolimus binds to the immunophilin FK-binding protein (FKBP) inhibits calcineurin

– Tacrolimus is 10-100 times more potent than cyclosporine in inhibiting immune responses

• Both tacrolimus and cyclosporine are extensively used along with glucocorticoids for the suppression of immune response in cases of solid organ transplantation

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PROLIFERATION SIGNAL INHIBITOR• Sirolimus (Rapamycin):

– Binds to FK-506 binding protein 12– It blocks molecular target of Rapamycin (mTOR) leads

to inhibition of interleukin driven T-cell proliferation – It is a potent inhibitor of B-cell proliferation and

immunoglobulin production– Also inhibits the mononuclear cell proliferative response

to colony-stimulating factors– Sirolimus-eluting coronary stents have been shown to

reduce re-stenosis– Uses: combination therapy in solid organ transplant,

management of Uveo-retinitis,

A derivative of sirolimus, everolimus, is a proliferation-signal inhibitor that may be of benefit in decreasing rejection in cardiac transplantationIt is being investigated for chronic cardiac allograft vasculopathy

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ADR• Glucocorticoids:

– Iatrogenic Cushing's Syndrome, Adrenal Suppression, Peptic Ulcers, Bacterial And Mycotic Infections, Myopathy

• Immunophilin Ligands:– Cyclosporine: Nephrotoxicity, Hypertension, Hyperglycemia,

Liver Dysfunction, Hyperkalemia, Altered Mental Status, Seizures, And Hirsutism

– Tacrolimus: nephrotoxicity, neurotoxicity, hyperglycemia, hypertension, hyperkalemia, and gastrointestinal complaints

• Sirolimus and Everolimus: Profound Myelosuppression (Especially Thrombocytopenia), Hepatotoxicity, Diarrhoea, Hypertriglyceridemia, And Headache

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MYCOPHENOLATE MOFETIL• It inhibits T- and B-lymphocyte responses, including

mitogen and mixed lymphocyte responses, probably by inhibition of de novo synthesis of purines

• Used to treat steroid-refractory graft-versus-host disease in hematopoietic stem cell transplant patients

• Toxicities: Gastrointestinal Disturbances (nausea and vomiting, diarrhea, abdominal pain) Headache, Hypertension and Reversible Myelosuppression (Primarily Neutropenia)

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THALIDOMIDE• It has significant immunomodulatory actions and is

currently studied for over 40 different illnesses• Currently used in the treatment of multiple

myeloma at initial diagnosis and for relapsed-refractory disease

• Response rates from 20 to 70%• The most important toxicity is teratogenesis.• Other adverse effects of thalidomide include

peripheral neuropathy, constipation, rash, fatigue, hypothyroidism, and increased risk of deep vein thrombosis

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IMiDs• Immunomodulatory derivatives of thalidomide• Lenalidomide is an IMiD that in animal and in vitro

studies has been shown to be similar to thalidomide in action, but with less toxicity, especially teratogenicity

• Showed its effectiveness in the treatment of the myelodysplastic syndrome with the chromosome 5q31 deletion

• CC-4047 (Actimid) is another IMiD that is being investigated for the treatment of myelodysplastic syndrome, myeloma, and prostate cancer.

Selective cytokine inhibitory drugs (SelCIDs), are phosphodiesterase type 4 inhibitors with potent anti-TNF-α activity but no T-cell co-stimulatory activity

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Immunostimulants• Immunostimulants are substances that modulate the

immune system by stimulating the function of one or more of the system’s components

• Classified as– Biological response modifyers

• BCG• Levamisole• Thalidomide

– Recombinant proteins• Interferons

– Immunization – Others

• Thymosin• Immunocynin 08/04/2023 26Dr Aaditya

• Auto immune diseases:– Traditionally only immunodepressents were used– Low dose naltrexone (LDN) has been used in the treatment of

multiple sclerosis– Inosine Pranobex/Isoprinosine (Imunovir) may be helpful in

rheumatic diseases (lupus/SLE, rheumatoid arthritis), multiple sclerosis and alopecia areata

• IGIV used in the treatment of many disorders• β-Glucans (beta-glucans), echinacea are tried in

cancer, radiation, shock, prevention of infection, wound healing, etc.

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Recent advances in Immunostimulants

ANTIBODIES IN CLINICAL USE

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POLYCLONAL ANTIBODIES

• Antilymphocyte antibodies (ALG)

• Antithymocyte antibodies(ATG)

• Immune globulin Intravenous (IGIV)

• Hyperimmune immunoglobulins

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ATG AND ALG• Obtained by immunization of large animals

such as horses with human lymphoid cells• They lead to destruction of T cells and

impairment of cell mediated immunity• ATG for treatment of acute renal transplant

rejection ( 1.5 mg/kg per day for 7 -14 days) and for preparation of bone marrow transplantation

• ALG for preparation of bone marrow transplantation

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IGIV• Nonspecific polyclonal human

immunoglobulin

• Prepared from pools of healthy donors

• Leads to reduction in helper T cells, increase in suppressor T cells, and decrease in spontaneous Ig production

• Found to be useful in variety of immune syndromes ranging like ITP and SLE

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HYPERIMMUNE Ig

• IGIV prepared from pools of selected human and animal donors

• High titers of antibodies against a particular agent of interest

• Used for the prevention or treatment of various infections such as rabies, tetanus, CMV infections, hepatitis B virus

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OTHER PUTATIVE APPLICATIONS• Blocking the action of cell surface receptors

• Receptor binding and antagonism

• Induction of apoptosis, ADCC and CDC

• Inhibition of viral fusion and replication

• Induction of cell death by radiations

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MONOCLONAL ANTIBODIES (mAb)

• Antibodies produced from single clone of B cells

• More selective and specific

• Less toxic

• Can be produced on a large scale without compromising the uniformity of the product

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FIRST MONOCLONAL ANTIBODY•Was produced by Köhler and Milstein in 1975•Technique was somatic cell hybridization•Nobel prize in 1984 for Physiology and Medicine

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LIMITATIONS

• Human immune response – HAMA

• Gradually reducing efficacy

• Renal damage

• Weak interactions between mouse antibody and human FcγRs (reduced effector function)

• Mouse antibodies do not bind to human FcRn receptors ( reduced half life)

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SOLUTION

• Chimeric antibodies (-ximabs) – Variable region of mouse antibody with constant region of human antibody

Eg. Infliximab, Rituximab,Abciximab

• Humanized antibodies (- zumabs)– CDRs from a mouse antibody attached to human antibody.

Eg. Daclizumab,

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HUMAN MONOCLONAL ANTIBODIES

Transgenic mice Eg. Ipilimumab

Phage display libraries Eg. Adalimumab

Limitation – Lack of species cross reactive antibodies08/04/2023 39Dr Aaditya

MUROMONAB-CD3

• Murine monoclonal antibody Directed against the CD3 molecule on the surface of human thymocytes and mature T cells

• muromonab-CD3 blocks killing by cytotoxic human T cells and several other T-cell functions

• It has proved more effective at reversing acute rejection than conventional steroid treatment

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ANTIBODIES AGAINST TUMOURS

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Antitumor MABs• Alemtuzumab is a humanized IgG1 with a kappa chain that

binds to CD52 found on normal and malignant B and T lymphocytes, NK cells, monocytes, macrophages, and a small population of granulocytes.– Approved for the treatment of B-cell chronic lymphocytic leukemia– Patients receiving this antibody become lymphopenic and may also

become neutropenic, anemic, and thrombocytopenic

• Bevacizumab is a humanized IgG1 monoclonal antibody that binds to vascular endothelial growth factor (VEGF) and inhibits VEGF from binding to its receptor– Antiangiogenic drug inhibit angiogenesis in tumors– First-line treatment of patients with metastatic colorectal cancer

alone or in combination with 5-FU-based chemotherapy– Adverse events: hemorrhage, gastrointestinal perforations, 08/04/2023 42Dr Aaditya

Antitumor MABs• Cetuximab is a human-mouse chimeric monoclonal

antibody that targets epidermal growth factor receptor (EGFR) – Indicated for use in patients with metastatic colorectal cancer

whose tumours over express EGFR

• Gemtuzumab is a humanized IgG4 monoclonal antibody with a kappa light chain specific for CD33 (a sialoadhesion protein found on leukemic blast cells ) – Gemtuzumab is coupled to the cytotoxic agent, ozogamicin– Is approved for the treatment of patients 60 years and older in

first relapse with CD33 acute myelogenous leukemia – Adverse events severe myelosuppression, significant

hepatotoxicity 08/04/2023 43Dr Aaditya

Antitumor MABs• Rituximab: Chimeric murine-human monoclonal IgG1

(human Fc) that binds to the CD20 molecule on normal and malignant B lymphocytes– Approved for the therapy of patients with relapsed or refractory

low-grade or follicular, B-cell non-Hodgkin's lymphoma– drug appears to be synergistic with chemotherapy (eg,

fludarabine, CHOP) for lymphoma

• Trastuzumab is a recombinant DNA-derived, humanized monoclonal antibody that binds to the extracellular domain of the human epidermal growth factor receptor HER-2/neu– Blocks the natural ligand from binding and down-regulates the

receptor– Metastatic breast cancer in patients whose tumors overexpress

HER-2/neu08/04/2023 44Dr Aaditya

MABs Used to Deliver Isotopes to Tumours

• Arcitumomab is a murine F(ab’)2 fragment from an anti-carcinoembryonic antigen (CEA) antibody labelled with technetium 99m (99mTc) that is used for imaging patients with metastatic colorectal carcinoma (immunoscintigraphy) to determine extent of disease

• Capromab pendetide is a murine monoclonal antibody specific for prostate specific membrane antigen– coupled to isotopic indium (111In)– Used in immunoscintigraphy for patients with biopsy-confirmed

prostate cancer

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MABs Used to Deliver Isotopes to Tumours

• Ibritumomab tiuxetan is an anti-CD20 murine monoclonal antibody labeled with isotopic yttrium (90Y) or 111In– Radiation provides the major antitumor activity– Approved for use in patients with relapsed or refractory low-

grade, follicular, or B-cell non-Hodgkin's lymphoma, including patients with rituximab-refractory follicular disease

• Nofetumomab is a mouse monoclonal antibody coupled to 99mTc that is used for diagnostic purposes– It binds a 40 kD antigen found on many tumor cell types, but also

on some normal cells– Accurate indicator of extent of disease in biopsy-confirmed small

cell lung cancer except in those patients with brain or adrenal metastases08/04/2023 46Dr Aaditya

MABs Used to Deliver Isotopes to Tumours

• Tositumomab is an anti-CD20 monoclonal antibody and is complexed with iodine 131 (131I)– Two-step therapy in patients with CD20-positive, follicular non-

Hodgkin's lymphoma whose disease is refractory to rituximab and standard chemotherapy

– Toxicities: Severe Cytopenias such as thrombocytopenia and neutropenia

• Satumomab is a murine monoclonal IgG1 antibody that binds to Tumour Associated Glycoprotein – 2 (TAG- 2) expressed on colorectal and ovarian adenocarcinomas– It is labelled with 111In Chloride – Used to diagnostically determine extent of cancer 08/04/2023 47Dr Aaditya

MABs USED AS IMMUNO-SUPPRESSANTS AND ANTI-INFLAMMATORY AGENTS

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ANTI-TNF-ALPHA MABS• Blocking TNF-a from binding to TNF receptors on

inflammatory cell surfaces results in suppression of downstream inflammatory cytokines such as IL-1 and IL-6 and adhesion molecules involved in leukocyte activation and migration.

• An increased risk of lymphoma is common to such agents• Adalimumab is a completely human IgG1 approved for use

in rheumatoid arthritis– Adalimumab blocks the interaction of TNF-α with TNF receptors

on cell surfaces; it does not bind TNF-β– Administration of adalimumab reduces levels of C- reactive

protein, Erythrocyte Sedimentation Rate, Serum IL-6 and Matrix Metalloproteinases MMP-1 and MMP-3

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ANTI-TNF-ALPHA MABS• Etanercept is a dimeric fusion protein composed of human

IgG1 constant regions (CH2, CH3, and hinge, but not CH1) fused to the TNF receptor– It binds to both TNF-α and TNF-β and appears to have effects

similar to that of infliximab– Etanercept is approved for adult RA, Polyarticular-course Juvenile

RA, and Psoriatic Arthritis

• Infliximab is a human-mouse chimeric IgG1 monoclonal antibody– Approved for use in Crohn's disease, ulcerative colitis,

rheumatoid arthritis, ankylosing spondylitis, and psoriatic arthritis

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ALEFACEPT• It is an engineered protein consisting of the CD2-

binding portion of leukocyte-function-associated antigen-3 (LFA-3) fused to a human IgG1 Fc region (hinge, CH1, and CH2), approved for the treatment of plaque psoriasis

• It inhibits activation of T cells by binding to cell surface CD2, inhibiting the normal CD2/LFA-3 interaction

EFALIZUMAB• Recombinant humanized anti-CD11a monoclonal

antibody Withdrawn due to PML

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BASILIXIMAB• It is a chimeric mouse-human IgG1 that binds to

CD25, the IL-2 receptor alpha chain on activated lymphocytes

• It functions as an IL-2 antagonist Immunosuppressant

DACLIZUMAB• It is a humanized IgG1 that binds to the alpha subunit

of the IL-2 receptor• Its indications are identical to that of basiliximab

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OMALIZUMAB• It is an anti-IgE recombinant humanized monoclonal

antibody that is approved for the treatment of allergic asthma in adult and adolescent patients whose symptoms are refractory to inhaled corticosteroids

• Abciximab is a Fab fragment of a murine-human monoclonal antibody that binds to the integrin GPIIb/IIIa receptor on activated platelets and inhibits fibrinogen, von Willebrand factor, and other adhesion molecules from binding to activated platelets, thus preventing their aggregation

• Palivizumab is a monoclonal antibody that binds to the fusion protein of RSV, preventing infection in susceptible cells in the airways08/04/2023 53Dr Aaditya

FUTURE• Fully humanized monoclonal antibodies Epilimumab CTLA4 specific Denosumab RANK ligand specific Zanolimumab CD4 specific Golimumab TNF specific

• PEGylation of fragments certolizumab pegol for Crohn’s disease

• Abdegs – antibodies that increase IgG degradation

5503/03/2007 Monoclonal antibodies

Humanized MAbsAtlizumabBapineuzumabErlizumab Felvizumab Fontolizumab Inotuzumab ozogamicinLabetuzumabLintuzumabMatuzumabMepolizumabMotavizumabNatalizumab NimotuzumabNolovizumabNumavizumabOcrelizumab

PascolizumabPecfusituzumab Pectuzumab Pertuzumab PexelizumabRalivizumab RanibizumabSibrotuzumabSiplizumabSontuzumab Talizumab Toralizumab Tucotuzumab celmoleukin Umavizumab Urtoxazumab Visilizumab

Dr Aaditya

TGN1412- a disaster• CD28-SuperMAB• It is a humanised monoclonal antibody that not only binds

to, but is a strong agonist for, the CD28 receptor of the immune system's T cells

• B cell chronic lymphocytic leukemia (B-CLL) and rheumatoid arthritis

• In its first human clinical trials, in March 2006, it caused catastrophic systemic organ failure in the subjects

• Administered at a supposed sub-clinical dose of 0.1 mg per kg, some 500 times lower than the dose found safe in animals

• Hospitalization of six volunteers on 13 March 2006.• One patient developed cancer of the GI tract08/04/2023 56

Interferons in therapy• Have a broad spectrum of antiviral activities as well as

immunomodulating and antiproliferative properties

• Not available orally, must be given IM, SC or IV

• DNA recombinant technology - highly purified interferons

• IFNs when bound to polyethylene glycol (PEG) have substantially longer half lives. Results in stable and sustained concentrations

Adverse events• IFNα – immune mediated disorders, Alopecia

• IFNβ – local necrosis of the skin

• G-CSF – neutrophillic dermatitis08/04/2023 57Dr Aaditya

Interferons in therapy• IFNα2b – Condyloma acuminatum

- Chronic Hepatitis C- Chronic Hepatitis B, Chronic Hepatitis D?

( CML, melanoma, multiple myeloma, renal cell carcinoma)• IFNα2a - Chronic Hepatitis C

- Chronic Hepatitis D- Multiple sclerosis

• IFNαn3 - Condyloma acuminatum

• Pegylated IFNα2b/a - Chronic Hepatitis C

• IFN Alfacon - Chronic Hepatitis C

• IFNγ – Chronic granulamtous diseases- Systemic sclerosis, osteopetrosis

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Interleukin 2• Exerts its antitumor effects indirectly through

augmentation of its immune function

• High doses can produce tumor regression in cancers like metastatic melanomas and renal cell carcinoma

• About 2 – 5 % patients may experience complete remissions that are durable

• Side effects include: intravascular volume depletion, capillary leak syndrome, ARDS, hypotension, fever, hypersensitivity and impaired liver and renal functions.

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Interleukin - 11• Interleukin-11 (IL-11) is a cytokine that stimulates

hematopoietic stem cells as well as megakaryocytes, resulting in increased platelet production.

• It is produced commercially (Oprevelkin, Genetics Institute, Cambridge, MA, USA) by recombinant DNA in Escherichia coli.

• The commercial product is a 177 amino acid polypeptide.

• It is indicated for the prevention of severe thrombocytopenia and reduction of platelet transfusions in patients with non-myeloid malignancies

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GM-CSF (Filgrastim)• GM-CSF was first identified based on its ability to

stimulate the clonal proliferation of myeloid precursors in vitro.

• The biologic effects of GM-CSF are mediated via binding to receptors expressed on the surface of target cells.

• The GM-CSF receptor is expressed on granulocyte, erythrocyte, megakaryocyte, and macrophage progenitor cells as well as mature neutrophils, monocytes, macrophages, dendritic cells, plasma cells, certain T lymphocytes, vascular endothelial cells, uterine cells, and myeloid leukemia cells.08/04/2023 61Dr Aaditya

GM-CSFTherapeutic use Results with rhuGM-CSF

Fungal infections Decreases incidence, as an adjuvant with antifungal and chemotherapy

HIV infection and its complications

Increases CD4 counts, decreases viral load

Vaccine adjuvant Enhances antibody response to Hep C Vaccine. Increases seroconversion in flu vaccines

Antitumor therapy Prolongs disease free survival and overall survival

Immunotherapy for AML

Decreases risk of relapse

Mucositis, stomatitis & diarrhea

Reduces incidence and severity

Wound healing Decreases time to wound healing. Reduces mean ulcer surface area

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PegFilgrastim• The addition of a 20 kDa polyethylene glycol moiety to filgrastim virtually eliminate renal clearance.

• The major remaining mode of clearance of pegfilgrastim is the neutrophil itself through a ‘self-regulating’ mechanism .

• Single dose of pegfilgrastim after chemotherapy led to a steady state serum concentration of this cytokine during the post chemo-therapy period, through the neutrophil nadir until subsequent neutrophil recovery .

• Pegfilgrastim stimulates the expansion of early myeloid precursors and the more rapid maturation and differentiation of neutrophils.

• As adequate neutrophil recovery occurs, these cells clear pegfilgrastim from the serum through G-CSF receptor–ligand binding over a rapid time course of 24–48 h.

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PegFilgrastim• Clinical trials are needed to further define the role of pegfil-

grastim with other chemotherapy regimens and in other disease settings, particularly to explore more dose-dense regimens of every 2 weeks or even weekly chemotherapy.

• Although previous trials have administered pegfilgrastim 24 h after chemotherapy, there is interest in examining the dosing of pegfilgrastim on the same day as chemotherapy.

• Furthermore, to take advantage of the self-regulating properties of pegfilgrastim, studies of this agent in the setting of prolonged neutropenia such as the post-transplant setting and acute myeloid leukemia, are of particular interest.

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Technicalities And Formalities

Patents • The exclusive right of an inventor to manufacture

the product invented by him for a fixed period– Antibodies (murine, humanized or human)– All natural immune components used therapeutically

which are manufactured by a specific process• Interferons (INF-β 1a patent by Biogen, brand name AVONEX)• Interleukins (Oprevelkin)• G-CSF (filgastrim patent by AMGEN, brand name NEUPOGEN)

• www.Iprlawindia.com • www.freepatentsonline.com

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Technicalities And Formalities

Laws and guidelines• Guidelines of

– Source of biological substances (origin of feeder cells)– Fusion partner (mylenoma, human lymphoblastoid-B cell

line,etc)– Safety of production of biological substances (viral and

bacterial infections)– All the cell lines should be periodically reviewed and

compared with cryopreserved samples of cell lines– Quality controlProduction And Quality Control Of Monoclonal Antibodies Directive 75/318/EEC Dec06

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Technicalities And Formalities

Laws and guidelines• Laws regarding the research of new drugs due to

patent problems• Laws regarding manufacture of drugs due to patent

problems• US FDA has guidelines for the production, storage

and use of biological compounds

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Mechanism Of Autoimmunity(1) Exposure of self-reactive T lymphocytes to antigens previously

sequestered from the immune system (eg, lens protein, myelin basic protein).

(2) Molecular mimicry by invading pathogens, in which immune responses are directed at antigenic determinants on pathogens that share identical or similar epitopes with normal host tissue. This phenomenon occurs in rheumatic fever following Streptococcus pyogenes infection, in which heart damage is thought to arise from an immune response directed against streptococcal antigens shared with heart muscle. The suggested viral etiology of autoimmune diseases has been ascribed to immune responses (both cell-mediated and humoral) directed against virus epitopes that mimic sequestered self antigens.

(3) Inappropriate expression of class II MHC molecules on the membranes of cells that normally do not express class II MHC (eg, islet β cells). Increased expression of MHC II may increase presentation of self peptides to T helper cells, which in turn induce CTL, TDTH, and B-lymphocyte cells that react against self antigens08/04/2023 69Dr Aaditya

IMMUNOSUPPRESSIVE ANTIBODIES

• Development of hybridoma technology by Milstein and Kohler in 1975

• Hybridomas consist of antibody-forming cells fused to immortal plasmacytoma cells

• Genetic engineering techniques involve production of chimeric and humanized versions of murine monoclonal antibodies

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CYTOTOXIC AGENTS• Azathioprine (Antimetabolite) produces

immunosuppression by interfering with purine nucleic acid metabolism at steps that are required for the wave of lymphoid cell proliferation that follows antigenic stimulation

• Cyclophosphamide (Alkylating Agent) destroys proliferating lymphoid cells

• Leflunomide is an inhibitor of pyrimidine synthesis

• Hydroxychloroquine suppress intracellular antigen processing and loading of peptides onto MHC class II molecules by increasing the pH of lysosomal and endosomal compartments, thereby decreasing T-cell activation08/04/2023 71Dr Aaditya

RECENT CYTOTOXIC AGENTS• Ixabepilone

– An analog of epothilone B that blocks tubulin polymerization in a way similar to that of the taxanes

– Is being tried for highly resistant malignant breast cancer and non squamous cell lung cancer

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