Inhibition of Natural Cytotoxic Rabbit Antibody by Human IgM: Production of Nontoxic Rabbit Serum for Use As Complement Source

Abstract

A simple method for the production of nontoxic rabbit serum has been developed. Small amounts of human IgM completely inhibited the cytotoxic activity of the natural serum antibody in normal rabbit serum reactive with human cells. IgM from both normal human sera and from the sera of patients with Waldenström's macroglobulinemia had similar inhibitory activity. Macroglobulins from mouse and rabbit sera were inactive. The human IgM did not interfere with complement activity or with the activity of cytotoxic antibodies from other species.