B-cell anergy is one mechanism utilized to expunge autoreactive immunoglobulin specificities. Anergic B-cells survive in a state of diminished antigen receptor responsiveness, and are deleted by Fas-mediated apoptosis induced by T effector cells. In normal B-cells sensitivity to Fas-directed cell death can be regulated by IL-4R and sIg signals that produce a state of Fas-resistance. The hypothesis guiding this study is that anergic B-cells may, as a result of specific immune signals, become resistant to Fas-mediated apoptosis, thereby avoiding elimination and presenting the potential for subsequent activation and autoantibody production. Elements of this hypothesis have ramifications for B-cell immunocompetence and the regulation of apoptosis in general. For this reason, and because so little is known about the means by which Fas-resistance is triggered and established, it is proposed to explore protection against Fas-directed cell death in 3 stages. 1) Evaluate the capacity of IL-4 to oppose Fas-mediated apoptosis by anti-Ig, and determine the role of other T-cell-derived lymphokines, using standard cytotoxicity assays. 2) Determine the metabolic level at which resistance to Fas-mediated apoptosis is produced by IL-4 and by anti-Ig, by examining Fas-triggered events of protein tyrosine phosphorylation, ceramide production, and protease activation, using Western blotting, identification of radiolabeled lipids, and enzymatic assays of protein digestion, and evaluate the role of Bcl-x, through tests of gene and protein expression, and evaluation of overexpressing transgenic animals. 3) Assess induction of Fas-resistance in anergic B-cells derived from double transgenic mice, and monitor autoantibodies rescued through somatic cell hybridization of B-cells from normal animals in which resistance is generated in vitro. This work should lead to a fuller understanding of the signals and mechanisms that produce B-cell resistance to Fas-mediated apoptosis, and validate or refute the hypothesis described above, which has important implications for the pathogenesis of serological autoimmunity.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI040181-03
Application #
2672830
Study Section
Experimental Immunology Study Section (EI)
Project Start
1996-08-01
Project End
2000-07-31
Budget Start
1998-08-01
Budget End
2000-07-31
Support Year
3
Fiscal Year
1998
Total Cost
Indirect Cost
Name
Boston Medical Center
Department
Type
DUNS #
005492160
City
Boston
State
MA
Country
United States
Zip Code
02118
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