Elevated serum levels of a 90,000 daltons tumor-associated antigen in cancer and in infection by human immunodeficiency virus (HIV).

Levels of a 90,000 daltons monoclonal antibody-defined tumor-associated antigen, termed 90K, were measured in the serum from 649 patients with various types of cancer and 1215 patients infected by the human immunodeficiency virus (HIV). Significantly increased 90K serum levels (12.1 +/- 0.5 U/ml) were found in cancer patients with respect to healthy controls (5.7 +/- 0.3 U/ml), with the highest levels in neoplasms of the breast, lung and gastrointestinal tract. In 355 patients with breast cancer, the elevation of serum 90K levels was more pronounced at advanced stages of disease. Mean levels of 90K for 1215 HIV-infected subjects (21.2 +/- 0.8 U/ml) were significantly higher than controls and cancer patients, and the levels progressively increased with disease worsening from asymptomatic infection to full blown AIDS. These data suggest that 90K is not merely a tumor-associated antigen and lead us to postulate it to be a signalling molecule whose production might be related to the immune deficit caused by pathogenetic events such as neoplastic progression and virus infection.