Gammopathy associated with advanced prostate carcinoma.

As proteinuria was found to be common in patients with prostate cancer, the possible presence of elevated urinary immunoglobulin (Ig) levels was investigated. First morning urine samples from 30 patients with androgen-dependent (AD) and 43 patients with androgen-independent (AI) prostate cancer were tested. A sensitive, solid-phase radioimmunoassay and polyclonal antibody interacting with IgG, IgA and IgM was used to screen urine samples. Compared with 15 normal, age-matched, healthy subjects, urinary Ig levels were elevated in 10 of 30 (33%) patients with AD prostate cancer and in 24 of 43 (56%) patients with AI prostate cancer. In the latter group, five of seven (71%) patients with prostatic SCC had elevated urinary Igs. Further analysis of ten urine samples containing increased urinary Ig levels, using antibodies specific for each heavy chain (gamma, alpha and mu) as well as each light chain (kappa and lambda), indicated that patients with a high or moderate elevation in Ig levels had polyclonal gammopathy, whereas those with a low increase in urinary Igs had monoclonal gammopathy of the IgG class. These results indicate, for the first time, a high frequency of an abnormal increase in Ig levels in patients with advanced prostatic carcinoma.