T-INDEPENDENT BUT NOT T-DEPENDENT ANTIGENS MAINTAIN SURFACE LG OF LYMPHOCYTES

The effect of T [thymus derived] independent (TIA) and T dependent (TDA) antigens on the surface Ig [immunoglobulin] of 24 h cultured rabbit spleen cells was investigated by 2 techniques. The proportion of cells bearing surface Ig was determined by direct rosette formation with anti-light chain allotype-coated erythrocytes. The total amount of surface Ig was estimated by labeling the cells with anti-allotype 125I-labeled Fab fragments. The addition of TIA resulted in the maintenance of the proportion of Ig-bearing cells almost to the initital level, an effect which could not be obtained with any of the TDA tested. The same type of effect was observed when the total amount of surface Ig was measured, i.e., there was a slight reduction (about 24%) in the amount of surface Ig in cultures to which TIA were added and an almost 6-fold reduction (about 70%) in cultures to which TDA, Con [concanavalin] A, or no antigen was added. Some but not all of the TIA were able to induce [3H]TdR [thymidine] incorporation in 3 day spleen-cell cultures. The common feature of TIA is the ability to stimulate the turnover of B[bone marrow-derived]-cell surface Ig, usable for any easy screening of TIA.