Plasma cells and their precursors. II. Kinetics of B-memory cell production in rabbits.

Rabbits were irradiated with 4.5 Gy in order to eliminate completely preexisting antibody-forming cell precursors. Sheep red blood cells were administered 24 h or 8 days after irradiation in order to induce the production of IgG B-memory AFCP. Resulting B-memory cells were triggered into antibody synthesis by a second dose of SRBC given 8 days after the challenge; the resulting IgG antibody clones were analyzed by isoelectric focusing. Memory IgG antibody clones were detectable from the third day after secondary immunization onward. It is concluded that antigen administered as early as 24 h after the irradiation induces B-memory cell production equally well as primary immunization 8 days after the irradiation. This B-memory cell production proceeds in the absence of detectable primary IgG antibody formation. Irradiated non-immunized rabbits showed spontaneous reappearance of IgG-AFCP with specificities to SRBC. In sharp contrast to the specifically induced production of B-memory IgG-AFCP mentioned above, this process took more than two months to reach potentialities comparable to those of "preexistent" AFCP present in normal, control rabbits.