Characterization of mouse CD6 with novel monoclonal antibodies which enhance the allogeneic mixed leukocyte reaction.
Human CD6 is a cell surface protein expressed by thymocytes, mature T cells, a subset of B cells and certain cells of the brain. On human T cells, CD6 has been shown to act as a co-stimulatory molecule which modulates T cell receptor (TCR)-mediated T cell activation. To study further the recently identified mouse CD6 (mCD6), we generated and characterized a set of anti-mCD6 mAb. Anti-mCD6 mAb recognizing the mCD6 scavenger receptor cysteine-rich (SRCR) extracellular domains 1 and 3 were identified. mAb against SRCR domain 3, but not domain 1, inhibited the interaction of CD6 with a recently identified ligand, activated leukocyte cell adhesion molecule (ALCAM). Immunohistochemical analysis indicated that mCD6 expression was largely localized to the T cell areas of lymphoid tissue and, as previously reported in the human, CD6 was also expressed by neurons. CD6 was highly expressed on mouse T cells isolated from the spleen, lymph node and thymus as demonstrated by two-color immunofluorescence analysis. The CD4+ and CD8+ cells in these lymphoid compartments expressed similar levels of CD6. Immunoprecipitation studies showed that mouse thymocytes predominantly express a CD6 isoform of approximately 130 kDa, while splenocytes predominantly express a CD6 isoform of approximately 100 kDa. Anti-mCD6 mAb enhanced allogeneic mixed leukocyte reactions (MLR), indicating that CD6-ALCAM interactions may regulate the proliferative capacity of T cells.
Starling
G C
GC
Bristol-Myers Squibb Pharmaceutical Research Institute, Seattle, WA 98121, USA. Starling@BMS.Com
Whitney
G S
GS
Siadak
A W
AW
Llewellyn
M B
MB
Bowen
M A
MA
Farr
A G
AG
Aruffo
A A
AA
D020410:Activated-Leukocyte Cell Adhesion Molecule; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000494:pharmacology; D000937:Antigen-Antibody Reactions / Q000187:drug effects; D015703:Antigens, CD / Q000276:immunology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology*; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D051381:Rats; D011917:Rats, Inbred Lew; D011993:Recombinant Fusion Proteins / Q000276:immunology / Q000378:metabolism; D013045:Species Specificity
D020410:Activated-Leukocyte Cell Adhesion Molecule; D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; C062279:CD6 antigen; D006023:Glycoproteins; D011993:Recombinant Fusion Proteins