© 2008, ycmou. all rights reserved.1 online counseling resource ycmou elearning drive… school of...

© 2008, YCMOU. All Rights Reserved. 1

Online Counseling ResourceYCMOU ELearning Drive…

School of Architecture, Science and TechnologyYashwantrao Chavan Maharashtra

Open University, Nashik – 422222, India


OC-SBT052-CP3-01

Introduction

Programmes and Courses SEP–SBT052–Unit-03

School of Science and Technology, Online Counseling Resource…


Credits

Academic Inputs by Arun Punaji More.

M.Sc. (Microbiology) Experience: 11 Years [email protected]



How to Use This Resource Counselor at each study center should use this presentation to deliver

lecture of 40-60 minutes during Face-To-Face counseling.

Discussion about students difficulties or tutorial with assignments should

follow the lecture for about 40-60 minutes.

Handouts (with 6 slides on each A4 size page) of this presentation should

be provided to each student.

Each student should discuss on the discussion forum all the terms which

could not be understood. This will improve his writing skills and enhance

knowledge level about topics, which shall be immensely useful for end

exam.

Appear several times, for all the Self-Tests, available for this course.

Student can use handouts for last minutes preparation just before end

exam.



Learning Objectives

After studying this module, you should be

able to: Define the term hypersensitivity and

allergy Describe the various symptoms of type I

hypersensitive reactions. Describe the mechanism of type I

reaction.



Introduction - 1 The main function of immune

system is to defend the host from the attack of foreign invading pathogens and their harmful products effectively and efficiently.

However many time there are some collateral damages to the local tissues from the immune reactions.



Introduction-2 Some time the persistent exaggerated

immune response in a localized tissue causes disease condition.

Preexposure to foreign antigens make the immune system more sensitive to mount more massive immune response which cause tissue damages.

In this module students shall learn about the over amplified immune reactions called as hypersensitive reactions.



Hypersensitive Reactions The over amplified immune reactions to

preexposed antigens causing tissues damages are called as hypersensitive reactions.

On the basis of mechanisms involved hypersensitive reactions are classified as Type I hypersensitive reactions Type II hypersensitive reactions Type III hypersensitive reactions Type IV hypersensitive reactions



Type I Hypersensitive Reactions-1 Type I hypersensitive reactions are

mediated by IgE antibody and vasoactive chemicals released by IgE antibody-coated mast cells.

Type I hypersensitive reactions are also called as immediate type of hypersensitive reactions or allergy since they occur within some minutes after the exposure to preexposed antigens.

The type I hypersensitive reactions can be mild to life threatening such as anaphylaxis.



Type I Hypersensitive Reactions-2 The antigens which are responsible for the

type I hypersensitive reaction are called as allergens which are mainly responsible to stimulate the production of IgE antibodies which bind to mast cells.

When such allergens come into body they specifically bind to these IgE receptors on mast cells leading to the cross linking the IgE receptors on the surface of mast cell resulting in release of vasoactive chemicals from the mast cells; the process is known as degranulation of mast cells.



Type I Hypersensitive Reactions-3

Vasoactive chemicals released in type I hypersensitive reaction Histamine Leukotrienes Eosinophil and neutrophil chemotactic factors.

(ECF-A, NCF-A) Platelet activating factor (PAF)



Type I Hypersensitive Reactions-4 Mechanism:-

1) Macrophage engulfallergen and present it toTH2 lymphocyte.2) TH2 cell secrete variouslymphokines stimulating B cell to differentiate into Plasma B cell which secrete IgE Ab.3) The IgE Ab get attachedto the mast cells, basophilesas their surface receptor.4) When these cells come into contact of the same allergen, they degranulate.



Type I Hypersensitive Reactions-5



Type I Hypersensitive Reactions-5 Histamine and leukotrienes both have

similar physiological effects. Both histamine and leukotrienes cause

vasodilatation and increased vascular permeability.

These effects of histamine and leukotrienes provide beneficial effects in antiparasitic immunity in which increased increased vascular permeability facilitates extra vascular recruitment of neutrophils, eosinophils, monocytes and IgG antibody which collectively damage the parasites.



Type I Hypersensitive Reactions-6 Depending upon the severity type I

hypersensitive reaction is grouped as Anaphylaxis Non anaphylaxis reactions.

The type 1 hypersensitive reactions developed as consequence of number of complex factors such as nature of foreign antigens, sensitizing route of their administration, dose and genetic constituent of the person.



Type I Hypersensitive Reactions-7 Anaphylaxis:-

Anaphylaxis is severe systemic type I hypersensitive reaction characterized by nausea, pallor, hypo tension, itching, wheezing, cynosis, abdominal pain, urticaria and loss of consciousness.

All these signs and symptoms developed within very short time i. e. within 5 to 10 minutes.

Anaphylaxis reactions can developed in sensitized persons after inoculation of venom by stinging insect,



Type I Hypersensitive Reactions-8 The common allergens causing

anaphylaxis are shellfish, penicillin, bees, latex, pollens, animal dander and animal food,foreign serum, egg albumin and wasps.

The allergens are defined as non parasitic antigens stimulating abnormally high amount of IgE antibodies.

The anaphylaxis reactions to the above allergens can be detected by demonstrating antigen specific IgE by enzyme linked immunoassay or by radio immunoassay.



Type I Hypersensitive Reactions-9 Non anaphylactic reactions:-

The non anaphylaxis reactions include allergy to foods characterized by nausea, abdominal discomfort, vomiting and diarrhoea.

Eczema, asthma and rhino-conjunctivitis are the common examples of non anaphylactic reactions.

The chronic urticaria is example of type 1 hypersensitive reactions to auto antigens.

Hay fever is example of non anaphylactic hypersensitive reaction.



What We Learn….. The definition of type 1 hypersensitive

reactions. The definition of anaphylactic reactions. The definition of non anaphylactic

reaction. Examples of type 1 hypersensitive

reactions. Diagnosis of type 1 hypersensitive

reactions.



Critical Thinking Question

Why development of type I hypersensitive reaction can be fatal?



Hints For Critical Thinking Question

Type I reaction can result into shock.



Study Tips

Book Title: Title: ImmunologyImmunology Author:Author: Richard A. Goldsby, Thomas Kindt,

Barbara A. Osborne. Publication:Publication: W.H. Freeman and Company, New

York. Book

Title: Title: Textbook of MicrobiologyTextbook of Microbiology Author:Author: R. Anathanarayan & C.K.J. Paniker Publication:Publication: Orient Longman publication,

Chennai.


End of the Presentation

Thank You !

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