f.76. nkt cell populations are not decreased in the majority of patients with xiap deficiency
TRANSCRIPT
F.75. Molecular and Functional Studies in T Cellsfrom Healthy Carriers of FOXP3 MutationsRosa Bacchetta,1 Sara Di Nunzio,1 Lucia Beatrice Perroni,2
Laura Passerini,1 Sarah Allan,3 Alicia Alstad,3 Anne Junker,3
Megan Levings,3 Maria Grazia Roncarolo.4 1San RaffaeleHospital, Milan, Italy; 2Galliera Hospital, Genoa, Italy;3University of British Columbia, Vancouver, BC, Canada;4VIta Salute San Raffaele University, Milan, Italy
IPEX is a severe genetic autoimmune disease character-ized by immune dysregulation, polyendocrinopathy, entero-pathy and X-linked inheritance. The disease is due tomutations in FOXP3, a transcription factor crucial fordifferentiation and function of naturally occurring CD4+CD25+ regulatory T (Treg) cells and for the maintenance ofperipheral tolerance. FOXP3 is an X-linked gene that issubject to X-inactivation. Therefore, female carriers ofFOXP3 mutations are expected to be mosaics of cellsexpressing the wild type (wt) or the mutated (mut) alleleof FOXP3, although they are healthy with no clinical historyof autoimmune manifestations. In order to investigate thewt/mut FOXP3 distribution in different peripheral T cellsubsets of healthy carriers, we set up a method to evaluate,at cellular level, both the pattern of X-inactivation and thepresence of FOXP3 mutation. We performed X-inactivationanalysis on freshly isolated and/or in vitro expanded CD4+CD25+/CD25- T cells, purified naive/ memory T cells and invitro stimulated Ag-specific T cells derived from mothers ofIPEX patients carrying FOXP3 mutations in different sites ofthe gene. Preliminary results demonstrate that a randomdistribution of wt/mutFOXP3 expressing cells does notalways occur. For example, a predominant expression ofwtFOXP3 was observed in the Treg cells from amother carrierof a fork head binding domain mutation. This study willprovide useful insights into the role of FOXP3 mutations inthe development and function of Treg cells and Ag-specific Teffector cells and will contribute to a better understandingof the genotype-phenotype correlation in IPEX.
doi:10.1016/j.clim.2008.03.187
F.76. NKT Cell Populations are Not Decreased in theMajority of Patients with XIAP DeficiencyRebecca Marsh, Joyce Villanueva, Kejian Zhang, KimberlyRisma, Alexandra Filipovich, Jack Bleesing. CincinnatiChildren's Hospital Medical Center, Cincinnati, OH
NKTcells are a unique population of Tcells that express aninvariant TCR which recognizes glycosphingolipid antigenspresented by the CD1d molecule. These cells are known to beabsent in X-linked Lymphoproliferative Disease (XLP) due toSAP mutation, and were previously reported to be decreasedin patients with XLP secondary to mutations in the BIRC4gene which encodes the X-linked Inhibitor of Apoptosis(XIAP). This lack of normal NKT cell populations has beenpostulated to contribute to disease pathogenesis in patientswith XLP. In order to further characterize NKT cell popula-tions in patients with XIAP deficiency, we studied wholeblood NKT cell levels in four patients over several months by
flow cytometric analysis. Identification was based on the co-expression of TCR-Vα24 and TCR-Vβ11, and results werecompared to 50 pediatric and adult controls. We found thatNKT cell populations were decreased in only 1 patient withXIAP deficiency. The other patients displayed normal orincreased NKT cells compared to controls. We conclude thatNKT cell populations are not decreased in the majority ofpatients with XIAP deficiency, and disease pathogenesis islikely not dependent on a lack of NKT cells.
doi:10.1016/j.clim.2008.03.188
F.77. Can the Frequency of Memory B Cells be Usedto Diagnose Primary Antibody Failure?Elizabeth Bateman, Mary Lucas, Kerri Packwood, Lisa Ayers,Daniel Harrison, John Burden, Ross Sadler, Berne Ferry,Helen Chapel. Oxford Radcliffe Hospital NHS Trust,Oxford, United Kingdom
Since the reports of reduced numbers of CD27 memory Bcells and increased immature CD21low B cells in patientswith Common Variable Immune Deficiency (CVID), a numberof classification systems using B cell phenotyping have beenproposed. In a large European multi-centre trial using B cellphenotyping to define subgroups in CVID, the majority ofpatients were found to have reduced switched memory Bcells (CD19+CD27+IgD-). Classification of individuals bymeasurement of B cell subpopulations may help identifythe underlying immune defects and aid understanding of theaetiology of associated clinical manifestations. This studylooked at a cohort of patients with recurrent infection, butno evidence of any primary antibody deficiency andcompared them with patients with either CVID, IgG subclassdeficiency, selective IgA deficiency or specific antibodydeficiency. Memory B cell phenotypes were assessed by flowcytometry using the whole blood method. Switched (CD19+CD27+IgD-) and unswitched (CD19+CD27+IgD+) memory Bcells, as well as transitional and CD21low B cell populationswere investigated. The aim of this study was to assesswhether class switched memory B cell frequency could beused to distinguish those patients presenting with recurrentinfections that had primary antibody failure, such as CVID, orpartial antibody failure such as IgA deficiency or IgG subclassdeficiency. This study will help in determining whethermeasuring memory B cell phenotype is a useful tool in thediagnosis of primary antibody failure.
doi:10.1016/j.clim.2008.03.189
F.78. Study of the Selective Response to DifferentGlucocorticoids (GC) in Subject Affected by IPEXMarilena Granzotto,1 Erica Valencic,2 Elisa Piscianz,1
Alberto Tommasini,2 Giuliana Decorti.2 1Institute for ChildHealth Burlo Garofolo, Trieste, Italy; 2University of Trieste,Trieste, Italy
Immuodysregulation, polyendocrinopathy, enteropathy X-Linked syndrome (IPEX) is a genetic failure of immune
S68 Abstracts