sIgD-negative B cells from neonatal mice do not respond to the thymus-independent antigen TNP-BA in limiting dilution cultures.
The majority of B lymphocytes in adult mice express both IgM and IgD on their surface (sIgM and sIgD). A small percentage of sIgM+ splenic B cells lack (or express very low levels of) sIgD. These cells have been termed "mu-predominant" (mu p) B cells. In neonatal mice (5 to 12 days of age), mu p B cells account for more than 50% of the sIg+ cells. There is conflicting evidence concerning the immunocompetency of mup cells in vitro. To study this question further, splenocytes from neonatal BALB/c mice were depleted of sIgD+ B cells by a panning procedure. A portion of the nonadherent (mu p) cell population was analyzed for residual sIgD+ cells by using indirect immunofluorescence in conjunction with the fluorescence-activated cell sorter (FACS). Such cells were then tested for their responsiveness to the thymus-independent (TI) antigen, trinitrophenyl Brucella abortus (TNP-BA), by using a limiting dilution culture system. Results indicate that the depletion of sIgD+ B cells and the decrease in the precursor frequency of splenocytes responding to TNP-BA are very similar, suggesting that virtually all of the responding B cells bear sIgD.
D000818:Animals; D000831:Animals, Newborn; D000955:Antigens, T-Independent / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D002469:Cell Separation; D002478:Cells, Cultured; D005260:Female; D007072:Immunoglobulin D / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D051381:Rats; D011917:Rats, Inbred Lew; D011947:Receptors, Antigen, B-Cell / Q000235:genetics / Q000276:immunology*; D013154:Spleen / Q000166:cytology; D013234:Stem Cells / Q000276:immunology
D000955:Antigens, T-Independent; D007072:Immunoglobulin D; D011947:Receptors, Antigen, B-Cell