Antigens and circulating immune complexes related to the primate retroviral glycoprotein SiSV gp70: prevalence and distribution in human sera.

We have shown previously that antigens and also circulating immune complexes related to the primate retroviral envelope glycoprotein SiSV gp70 correlate with early mortality and survival of 56 patients with acute leukemias and chronic myelogenous leukemia in blast crisis. The prevalence and general distribution of these antigens and immune complexes in human sera was therefore of obvious interest. We now report an analysis of a total of 200 sera from 166 patients. Of these 113 sera were obtained from 84 patients with acute or chronic leukemias and 87 from 82 non-leukemic subjects, including laboratory workers and patients with non-leukemic neoplasias. Antigens and immune complexes were determined by enzyme-linked immunosorbent assays (ELISA). The anti-SiSV gp70 antiserum used predominantly recognized the protein moieties of the glycoproteins. The distribution of SiSV gp70-related antigens and immune complexes was similar among leukemic and non-leukemic sera. The prevalence of SiSV gp70-related antigens was 53% and of SiSV gp70-related immune complexes 49% in all sera. SiSV gp70-related antigens were detected in a somewhat higher proportion of non-leukemic (69%) than leukemic sera (40%), whereas SiSV gp70-related immune complexes and cross-reactive antibodies were more evenly distributed in leukemic and non-leukemic sera (in 46 and 51% of leukemic and 54 and 51% of non-leukemic sera). Presence of antigens correlated with presence of SiSV gp70-related immune complexes in 71% of all sera, but in 13% of all sera antigens were detectable only by determining SiSV gp70-related immune complexes. Total circulating immune complexes did not correlate with SiSV gp70-related immune complexes. The origin and pathophysiological role of the antigens are discussed.