Cell Growth & Differentiation, Vol 7, Issue 1 107-114, Copyright © 1996 by American Association of Cancer Research

ARTICLES

Distinct patterns of Fas cell surface expression during development of T- or B-lymphocyte lineages in normal, scid, and mutant mice lacking or overexpressing p53, bcl-2, or rag-2 genes

T Li, K Ramirez and R Palacios
Department of Immunology, University of Texas M. D. Anderson Cancer Center, Houston 77030, USA.

Fas is a cell membrane protein involved in programmed cell death. In normal young mice, Fas was expressed on pluripotent stem cells, multipotent progenitors, pro-T and pre-T cells, most thymocytes, and a subset of CD4 and CD8 mature T lymphocytes. In contrast, Fas expression was switched off in B-cell and myelocytic progenitors and most pro-B and a proportion of pre-B cells and was switched on again later, but this occurred only in a subset of mature B lymphocytes. A lack of bcl-2 increased the proportion of Fas+ B-lymphocyte lineage cells and Fas+ CD4+ cells and decreased the percentage of Fas- CD8+ mature T-cell subsets. Overexpression of bcl-2 reversed this pattern of Fas cell surface expression. Interestingly, lack of p53 increased the proportions of Fas-expressing CD4 and CD8 mature T-cell subsets and of Fas- B-cell precursors but decreased that of Fas- mature B-lymphocyte populations. We conclude that the expression of Fas is regulated distinctly during the development of T and B lymphocytes. Although the products of neither bcl-2 nor p53 genes are essential for Fas cell surface expression on hematopoietic cells, these repressor and effector genes, respectively, of programmed cell death affect distinct subsets of lymphoid lineage cells at different stages of lymphopoiesis. Our results suggest that distinct combinations of effector and suppressor genes of programmed cell death act on distinct cell populations and at different stages of differentiation within the same cell lineage in the hematopoietic system.

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