IMMUNE-RESPONSE AGAINST BETA-GALACTOSIDASE ENZYME OF ESCHERICHIA-COLI AT PRECURSOR CELL LEVEL .1. ANALYSIS OF SECONDARY REPERTOIRE IN BALB-C MICE

The BALB/c secondary response against the β‐galactosidase (β‐gal) enzyme of E. Coli was analyzed at the precursor cell level by using the splenic focus technique. Our results indicate that in immunized mice, one out of 18000 B cells is able to recognize β‐gal. Among the families of anti‐β‐gal monoclonal antibodies, a subset of specific antibodies was detected which is capable of protecting the enzyme from heat denaturation. The frequency of clones making protecting antibodies is 1 out of 90000 and appears to be fairly constant among different individual mice. Further, the degree of heterogeneity of protecting antibodies analyzed in one individual is very high (250‐fold difference in affinity) but comparable to other secondary repertoires. Specific frequencies are compared with previous findings relative to secondary responses against artificial haptens. It is suggested that a different type of recognition exists between protein determinants and artificial haptens. In addition, the relatively high proportion of clones making antibodies of the protecting type suggests that only a small proportion of antigenic sites on the β‐gal is actually able to stimulate an immune response. Copyright © 1978 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim