Non-specific and DNP--erythrocyte rosette formation after contact sensitization with DNCB.

DNA--guinea-pig erythrocyte rosette-forming cells (RFC), as found after contact sensitization of guinea-pigs with DNCB, were shown to be highly sensitive to pretreatment with cyclophosphamide or X-irradiation, which suggests that these cells are B cells. The finding was confirmed by rosette-blocking experiments using an anti-immunoglobulin serum. It has already been shown that they are not directly related to antibody production. Possibly they represent precursors of antibody-producing cells. An increase in rosette formation, using non-antigenically related erythrocytes, was shown to parallel development of cell-mediated immunity (CMI) in the lymph nodes. These non-specifically induced RFC were also found to be B cells. Data were obtained which make it improbable that either proliferation or influx of B cells during development of CMI plays a major role in this increase. An alternative mechanism is suggested, while a possible role for these non-specifically induced RC is proposed.