CD5 is associated with the human B cell antigen receptor complex.
On human B cells the antigen receptor complex is composed of the membrane form of the immunoglobulin molecule and the non-covalently associated Ig alpha/beta heterodimer. A small subpopulation of normal B cells and chronic lymphocytic leukemia B cells express (analogous to T cells) the transmembrane molecule CD5, a counterstructure of B cell-specific CD72. Numbers of CD5+ B cells are increased in several physiological and pathological conditions. Moreover, CD5+ B cells are being held responsible for the production of autoreactive antibodies and seem to have signaling characteristics distinct from conventional B cells. On T cells, CD5 associates with the T cell receptor CD3 complex and ligation of CD5 leads to the generation of co-stimulatory signals, that act on T cell activation. We here demonstrate that CD5 is associated with the B cell receptor (BCR) complex and serves as substrate for BCR-induced tyrosine kinase activity. Hence, CD5+ B cells have a unique potential to modulate BCR signals.
Lankester
A C
AC
Department of Clinical Viro-Immunology, The Netherlands Red Cross Blood Transfusion Service, Amsterdam.
van Schijndel
G M
GM
Cordell
J L
JL
van Noesel
C J
CJ
van Lier
R A
RA
D015703:Antigens, CD / Q000032:analysis*; D001402:B-Lymphocytes / Q000737:chemistry*; D018956:CD5 Antigens; D006801:Humans; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000502:physiology; D011947:Receptors, Antigen, B-Cell / Q000032:analysis*
D015703:Antigens, CD; D018956:CD5 Antigens; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D011947:Receptors, Antigen, B-Cell