CIRCULATING IMMUNE-COMPLEXES IN LEPROSY SERA - DEMONSTRATION OF ANTIBODIES AGAINST MYCOBACTERIAL GLYCOLIPIDIC ANTIGENS IN ISOLATED IMMUNE-COMPLEXES

Circulating immune complexes (CIC) were assayed in sera of leprosy pat ients. Using an immunoassay for two mycobacterial antigens-phenolic gl ycolipid-I (PGL-I) and glycolipid IV (SL-IV)-sera from 65 patients wit h leprosy (38 lepromatous, 18 borderline, and 9 tuberculoid) were stud ied. The CIC were isolated by polyethylene glycol (PEG) precipitation, washed, treated with an acid buffer, neutralized, and tested using an enzyme-linked immunosorbent assay (ELISA). We demonstrated that CIC c ould contain IgG and IgM antibodies reacting against PGL-I and SL-IV. The high levels of antibodies in the precipitable CIC showed concordan ce with high levels in the original sera, although some patients prese nted high levels of precipitable CIC in the absence of high titers of antibodies in their sera. It was concluded that some of the CIC observ ed in patients with leprosy were composed of IgG and IgM immunoglobuli ns against specific mycobacterial antigens.