Production of IgG antibodies and enhanced response of nude mice to DNP-AE-dextran

DNP-AE-dextran, prepared by the binding of DNP-epsilon-aminocaproyl residues to animoethylated dextran (predominantly alpha-1,6-linked), induced a T-independent anti-DNP antibody response in mice. However, certain differences were observed between the response to this antigen in normal andnude mice. Thus, the antibody titers of nu/nu mice from day 10 to 38 after immunization were significantly higher than those of nu/+ controls. Furthermore, DNP-AE-dextran induced a weak secondary response in nu/+ but not in nu/nu mice. For both thymusless and normal mice the production of IgG in addition to IgM antibodies to DNP-AE-dextran could be established. The former included antibodies of the IgG1 subclass which were considered to be particularly thymus dependent (1). The higher response of nu/nu mice was reflected mainly in the increased production of IgG antibodies. Under the influence of a graft-vs-host reaction, a 10-fold increase in antibody titers to DNP-AE-dextran was observed, due entirely to an enhanced IgG response.