A B lymphocyte surface molecule mediating activation and protection from apoptosis via calcium channels.
A rat mAb (NIM-R5) was prepared against a 42-kD B cell activation Ag (p42). The expression of p42 is increased upon activation. NIM-R5 induces an increase of intracellular Ca2+, due to influx from the exterior milieu via calcium channels. This stimulation does not prejudice further stimulation with anti-Ig, and thus p42 constitutes an activation signal independent of membrane Ig. The antibody induces increased expression of class II molecules on resting B lymphocytes and prepares the cells for "spreading" when interacted with immobilized anti-class II antibody. The antibody alone is weakly mitogenic and comitogenic with IL-4 on resting B cells. Of particular interest, NIM-R5 induces proliferation and rescue from apoptosis in B cells activated in vitro. In conclusion, NIM-R5 induces an Ig-independent activation and proliferation of resting and activated B cells. This antibody does not recognize other known B cell activation Ag such as CD23, CD40, or CD72. We therefore propose that the p42 Ag is a glycoprotein with an important role in the regulation of B lymphocyte activation and survival.
Department of Immunology, National Institute for Medical Research, Mill Hill, London, U.K.
L
L
Santos-Argumedo
C
C
Teixeira
G
G
Preece
P A
PA
Kirkham
R M
RM
Parkhouse
D051997:ADP-ribosyl Cyclase 1; D000944:Antigens, Differentiation, B-Lymphocyte / Q000502:physiology*; D017209:Apoptosis; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002118:Calcium / Q000502:physiology; D015220:Calcium Channels / Q000502:physiology*; D002448:Cell Adhesion; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D007075:Immunoglobulin M / Q000502:physiology; D066298:In Vitro Techniques; D015847:Interleukin-4 / Q000494:pharmacology; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000502:physiology*; D008970:Molecular Weight; D011947:Receptors, Antigen, B-Cell / Q000502:physiology; D015398:Signal Transduction; D014407:Tumor Cells, Cultured
D000944:Antigens, Differentiation, B-Lymphocyte; D015220:Calcium Channels; D000949:Histocompatibility Antigens Class II; D007075:Immunoglobulin M; D008562:Membrane Glycoproteins; D011947:Receptors, Antigen, B-Cell; D015847:Interleukin-4; D051997:ADP-ribosyl Cyclase 1; D002118:Calcium