A monoclonal antibody to a constant determinant of the rat T cell antigen receptor that induces T cell activation. Differential reactivity with subsets of immature and mature T lymphocytes.
mAb R73 detects a T cell-specific surface molecule consisting of two disulfide-linked subunits of 40 and 46 kD, respectively, on 97% of peripheral rat T cells, as defined by the OX-52 marker. Of the few OX-52+ R73- cells, none are CD4+ but many express the CD8 antigen known to be present on rat NK cells. mAb R73 is mitogenic for unseparated spleen cells and for purified T cells. In the absence of non-T "accessory cells", stimulation by R73 requires artificial crosslinking of the mAb and is largely dependent on exogenous IL-2. Overnight incubation of purified T cells with crosslinked R73 mAb induces blastoid transformation, IL-2-R expression, and modulation of the R73 antigen. In the rat thymus, mature medullary cells express the R73 determinant at the same level as peripheral T cells, whereas 94% of CD4-CD8- thymocytes are R73-. The major CD4+8+ thymocyte population contains 25% R73- and 70% R73low cells. Thymocytes of the CD4-CD8+OX-44- subpopulation that are the direct precursors of CD4+CD8+ cells display a continuum of R73 antigen density from undetectable to very low levels. We conclude that R73 is most likely directed at a constant determinant of the rat alpha/beta heterodimeric TCR and suggest that CD8+ immature thymocytes are the first cells in the T cell differentiation pathway to express this molecule at their surface.
Genzentrum der Ludwig Maximilians Universität, München, Federal Republic of Germany.
T
T
Hünig
H J
HJ
Wallny
J K
JK
Hartley
A
A
Lawetzky
G
G
Tiefenthaler
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D002454:Cell Differentiation; D005434:Flow Cytometry; D008198:Lymph Nodes / Q000276:immunology; D008213:Lymphocyte Activation; D051381:Rats; D011919:Rats, Inbred Strains / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D015375:Receptors, Interleukin-2 / Q000502:physiology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology; D014018:Tissue Distribution
D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D011948:Receptors, Antigen, T-Cell; D015375:Receptors, Interleukin-2