Kinetics of immunoglobulin M and G responses of nude and normal mice to Trypanosoma musculi.

A sensitive and specific enzyme-linked immunosorbent assay was designed to measure the kinetics of Trypanosoma musculi-specific immunoglobulin M (IgM) and IgG responses in mice. Serum was obtained from congenitally athymic (nude) mice, their phenotypically normal, thymus-bearing littermates (NLM), and thymus cell-repaired nude mice (Nu-TC) at 6-day intervals throughout T. musculi parasitemia. NLM mice were shown to effect an antibody response to T. musculi that included an IgM to IgG shift and was correlated in time with reduction of parasite reproduction and stabilization of parasitemia. Nude mice were shown to effect a T. musculi-specific IgM response similar in onset and magnitude to that in NLM mice; this response was correlated in time with stabilization of parasitemia. Nu-TC mice were shown to effect IgM and IgG responses to T. musculi similar in time and magnitude to those in NLM mice. In marked contrast to NLM mice, Nu-TC mice did not exhibit suppression of T. musculi-specific IgM production after the IgM to IgG shift in response to this parasite.