Identity of a T-lymphocyte inhibitor with mouse immunoglobulin in the serum of tumour-bearing mice.

A component of the serum of tumour-bearing mice has been shown to be inhibitory to the immunological function of normal mouse T cells. This factor fractionates with monomeric immunoglobulin upon gel filtration. Studies were carried out utilizing goat antisera to the major immunoglobulin chains of mouse Ig (kappa, gamma, alpha and mu) mixed with the immunoglobulin-rich fraction of serum from normal mice and tumour bearers and passed through immunoadsorbent columns prepared with rabbit anti-goat immunoglobulin. Such studies showed that the inhibitory activity in tumour-bearing serum could be removed after treatment with anti-kappa, anti-gamma and anti-mu chain antisera but not by treatment with either anti-alpha chain or goat immunoglobulin. That the inhibitory activity of tumour-bearing immunoglobulin could be attributed to simple quantitative differences in the levels of IgM and IgG in the test samples was discounted by quantification of the amounts of immunoglobulins in normal and tumour-bearing sera.