CD5+ and CD5- B1-like lymphocytes in healthy guinea pig

Spleen, lymph node, and peripheral blood lymphocytes from healthy guinea pigs (gp) were examined for their ability to produce polyreactive autoantibodies to a battery of self-antigens and to cryptic determinants (phosphatidylcholine) on bromelain-treated mouse red blood cells (Br-MRBC). The mouse monoclonal antibody (Mab) 8BE6 anti-gp pan-T (CD5) marker was used for identification of CD5+ B1 cells by the plaque-forming assay (PFC), immunofluorescence, complement-mediated cytotoxicity, and immunocytochemistry. The detection of CD5+ cells by the 8BE6 Mab depended on the method used. They were better demonstrated by cytolysis and immunocytochemistry than by FACS analysis. By the latter method, the level of the CD5+ B cell subpopulation was associated neither with the age of the gp nor with the organ examined. Similarly wide ranges of PFC were detected in untreated or LPS-treated animals regardless of age and organ. The vast majority of the LPS-stimulated IgM antibody-secreting B lymphocytes reacting with the Br-MRBC, and those producing natural autoantibodies, did not bind the 8BE6 Mab.