Complement receptor lymphocytes in the rabbit. II. The effect of immunization on the complement receptor lymphocyte population in the craining lymph node.

In an attempt to determine the effect of immunization on the size and nature of the complement receptor lymphocyte (CRL) and surface immunoglobulin (SIg)-bearing lymphocyte (B cell) populations, rabbits were injected with 1 mg alum-precipitated keyhole limpet hemocyanin and the cells of the draining popliteal lymph nodes were examined at various intervals for these populations. Comparison to unimmunized control lymph nodes revealed that immunization resulted in an approximate doubling of the percentages of both CRL and B cell populations by the peak of the response, while the cell number increased about 7-to 8-fold. Kinetic analysis of the response indicated that the percentages of CRL and B cells increased essentially in parallel beginning within 40 h after immunization. Simultaneous assay of complement receptor (CR) and SIg disclosed that CRL remained a B cell subpopulation throughout the response. To determine whether cell division could account for the increases in total cell number and per cent CRL and B cells, immunized rabbits were given 3H-thymidine in vivo, and the fraction of labeled (dividing) cells was determined by autoradiography. Results of such experiments were consistent with the possibility that the early increase in cell number and the increase in CRL and B cell percentages were a result of trapping and/or homing of lymphocytes migrating from the peripheral blood. A significant amount of lymphocyte division occurred during later stages of the response.