CD2 ligation abrogates antigen-independent apoptosis in B cells.
We have described recently the prevention of apoptosis by CD2-soluble CD48 interaction on antigen B cell receptor occupancy. Here, we show that CD2 ligation is also able to interfere with B cell receptor-independent apoptosis pathways such as spontaneous death in spleen B cells or serum deprivation and hydrogen peroxide exposure in the BAL-17 cell line. In all cases, CD2 ligation induces a signal that prevents the downregulation of Bcl-2 expression. The specific CD2 signal pathway involved in this phenomenon is still unknown. As reported, CD2 did not appear to induce Ca2+ mobilization, phosphatidylinositol turnover, or PKC translocation in B cells. Nevertheless, we show that CD2 receptor ligation is coupled to the tyrosine phosphorylation pathway in B cells. These observations indicate that CD2 is functionally able to trigger at least an early signal that could play a role in apoptosis blockage B cells in addition to the adhesion one. The results suggest the participation of cellular membrane receptors other that CD40 in apoptosis rescue, not only in the antigen-dependent but also in the antigen-independent phases of B cell lymphopoiesis.
Baixeras
E
E
Centro Nacional de Biotecnologia (C.S.I.C), Universidad de Madrid, Spain.
Moreno
M C
MC
Martinez-A
C
C
D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects / Q000276:immunology*; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*; D018801:CD2 Antigens / Q000187:drug effects / Q000378:metabolism*; D000071178:CD48 Antigen; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D005609:Free Radicals / Q000378:metabolism; D008024:Ligands; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D010766:Phosphorylation; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism
D015703:Antigens, CD; D018801:CD2 Antigens; D000071178:CD48 Antigen; C000604066:Cd48 protein, mouse; D016895:Culture Media, Serum-Free; D005609:Free Radicals; D008024:Ligands; D014443:Tyrosine