Clonal nature of the immune response to phosphorylcholine. I. Specificity, class, and idiotype of phosphorylcholine-binding receptors on lymphoid cells.

The relationship between receptor molecules on antigen-binding lymphocytes (ABC) and antibody produced by antibody-secreting cells was studied in inbred strains of mice using the immune response to phosphorylcholine (PC) as a model system. Splenic and lymph node lymphocytes of nonimmune mice possess rare lymphocytes which bind (125)I-labeled PC-bovine serum albumin. The frequency of PC-ABC increases after immunization and is paralleled by a rise in the frequency of PC-specific antibody-producing cells. Both of these responses are thymus independent. The receptors on these ABC display specificity for PC and are exclusively of the IgM class. In one of the strains, BALB/c, the receptors possess the same idiotype and fine degree of specificity for PC and two of its analogues, glycerophosphorylcholine and choline, that are characteristic of a PC-binding myeloma, HOPC 8. Furthermore, the idiotype and class of the receptor in these mice do not change during the course of the immune response. These data provide more direct evidence for the immunelogic relevance of receptor-bearing lymphocytes.