The T-cell independent antigen, NP-ficoll, primes for a high affinity IgM anti-NP response

In a number of different strains of inbred mice, immunization with a hapten coupled to a protein carrier results in production of homogeneous serum antibodies. At the genetic level this corresponds to the use of a very limited set of variable region genes in the actively secreting B-cells. In contrast, immunization with the same hapten coupled to a T-cell independent (TI) carrier produces a heterogeneous antibody response. Here we show that successive immunizations of C57BL/6 mice, first with the hapten NP coupled to ficoll, a TI carrier, and then one month later with a subliminal dose of the same hapten coupled to a protein carrier, generate a novel set of hybridomas. These hybridomas produce antibodies which are of the IgM isotope and which lack somatic mutation. Some of these antibodies have a much higher affinity for NP than do antibodies which use the prototypical gene combination (V_H186.2-λ1) of the strain specific response in C57BL/6 mice.