B Cell Tolerance

Abstract

The mechanisms of B cell tolerance were studied in an attempt to learn whether B cells rendered tolerant are present in the immune system in a potentially responsive form. The author tested the in vitro anti‐trinitrophenyl (TNP) antibody‐forming cell (anti‐TNP AFC) response to TNP‐immunogens and polyclonal B cell activators (PBA) of spleen cells taken from mice injected with a tolerogen, TNP‐carboxymethylcellulose (TNP‐CMC). Spleen cells from mice injected 5 days previously with 10 μg of TNP‐CMC did not respond to TNP‐sheep red blood cells (TNP‐SRBC), T‐dependent (TD) antigen or TNP‐Ficoll, T‐independent (TI) antigen. However, the same spleen cells responded to PBA, lipopolysaccharide (LPS) of Salmonella enteritidis and purified protein derivative (PPD) of BCG. The results indicate that B cells specific for TNP are present in a potentially responsive form. Spleen cells from mice injected with 500 μg of TNP‐CMC did not respond to either TNP‐immunogens or PBA. The state of unresponsiveness to PBA lasted for 12 days after the tolerogen injection. Responsiveness to PBA reappeared within the short period of 2 days, whereas unresponsiveness to TNP‐immunogens lasted much longer. Unresponsiveness to PBA was relieved considerably by treating tolerant spleen cells with the proteolytic enzyme trypsin before in vitro stimulation. These results indicate that B cells rendered refractory are present in the immune system in a potentially responsive form.