title: A new lymphocyte surface antigen defined by a monoclonal antibody (9F3) to the T cell population expanding in MRL/Mp-lpr/lpr mice.
abstract: This report is a description of the pattern of reactivity of a rat monoclonal antibody (MAb 9F3) directed to the abnormal T cells expanding in MRL/Mp-lpr/lpr (MRL/lpr) mice. By using single- and two-color flow cytofluorometry analysis, this MAb was found to stain brightly 90 to 98% of lymph node (LN) T cells from MRL/lpr, C57BL/6-lpr/lpr (B6/lpr), and C3H/HeJ-lpr/lpr mice, and approximately 10 to 50 times less intensely 55 to 70% of T cells from control congenic +/+ mice. The study of in vitro proliferative responses of sorted cells from MRL/+ mice demonstrated that 9F3- T cells react better to phytohemagglutinin and allogeneic cells but less well to concanavalin A (Con A) than 9F3+ T cells. Upon Con A-induced blastogenesis, 65% of 9F3- T cells became 9F3+ whereas all 9F3+ remained 9F3+. Although only 15% of thymocytes, which included hydrocortisone-resistant population, were 9F3+ in +/+ mice, up to 60% of bright 9F3+ cells were detectable in the thymus of lpr-bearing mice after the onset of lymphoproliferation. Moreover, in both lpr-bearing and normal mice, the 9F3 MAb stained the totality of resting or mitogen-activated B cells. The 9F3 MAb also reacted with 100% of bone marrow (BM) cells, irrespective of the lpr gene. However, a subset of bright 9F3+, large BM cells was increased in frequency in lpr-bearing mice compared to congenic controls. Although expressed on macrophages, granulocytes, and erythrocytes, the 9F3 antigen was not in liver, kidney, and brain tissue of MRL/+ mice. Because the cell and tissue distributions of the 9F3 antigen do not correspond to any previously described murine antigen, this antigen may represent a new surface marker that should prove useful for studying lymphohemopoietic cell differentiation in normal and lpr-bearing mice.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000937:Antigen-Antibody Reactions; D000954:Antigens, Surface / Q000235:genetics / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology; D001854:Bone Marrow Cells; D008198:Lymph Nodes / Q000166:cytology; D008213:Lymphocyte Activation; D007959:Lymphocyte Culture Test, Mixed; D008221:Lymphoid Tissue / Q000166:cytology; D051379:Mice; D008817:Mice, Mutant Strains; D008934:Mitogens / Q000494:pharmacology; D010641:Phenotype; D051381:Rats; D011917:Rats, Inbred Lew; D013601:T-Lymphocytes / Q000145:classification / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D008934:Mitogens