Nonorgan-specific autoantibodies and immunoglobulin allotypes in relatives of patients with monoclonal gammopathy.

Polyclonal immunoglobulin increase, rheumatoid factor, antinuclear antibodies and cold lymphocytotoxins were detected 10, 8, 7 and 8 times, respectively, in a group of these informative families (22, 17 and 29 subjects tested, respectively). Each family included at least 1 subject with a monoclonal gammopathy in addition to that of the proband. No correlation could be shown between any of these abnormalities and Gm haplotypes. Nonetheless, it is worth noting that 6 out of 41 relatives under 30 years of age had cold lymphocytotoxins.