Elevated titers of cell-free interleukin-2 receptor in serum and cerebrospinal fluid specimens of patients with acquired immunodeficiency syndrome.

A sensitive monoclonal antibody based ELISA was used to detect cell-free interleukin-2 receptor (IL-2R) in the body fluids of patients with acquired immune deficiency syndrome (AIDS), a variety of other disease conditions and a control group of apparently healthy (heterosexual and homosexual) males. Two of the 25 control donors showed low titers (1:8) of IL-2 receptor in the serum samples; the cerebrospinal fluid (CSF) specimens from these individuals proved negative. However, serum and CSF specimens from all the 9 patients with AIDS showed significantly elevated titers (range 1:128 to 1:4096) of IL-2 receptor. The presence of moderate titers (range 1:128 to 1:512) of circulating IL-2 receptor could also be detected in all of the 4 patients with acute lymphocytic leukemia. IL-2 receptor was detectable in the CSF and/or serum specimens from 3 of 3 patients with lung cancer, 3 of 4 patients with acute hepatitis B infection, and 2 of 3 patients with multiple sclerosis. IL-2 receptor could not be detected in the serum or CSF specimens originating from patients with legionellosis (3/3), asthma (3/3), or those with non-pulmonary febrile bacterial infections (4/4). It is concluded that soluble IL-2 receptor may be found in serum or CSF specimens from patients with certain (but not all) disease conditions including AIDS. The conspicuously elevated titers of cell-free IL-2R in the body fluids of patients with AIDS may contribute to the drastic impairment of the immune system regulation observed in such patients.