The identification of specific antigens in circulating immune complexes by an enzyme‐linked immunosorbent assay: detection of bovine x‐casein IgG complexes in human sera

Publisher Website
Google Scholar
Abstract
Circulating immune complexes have been implicated in the development of tissue injury in many chronic disease states, but in most instances the inciting antigens have not been identified. This report describes the development of a sensitive enzymelinked immunosorbent assay which can be used to screen rapidly and simultaneously the immune complexes of numerous sera for the presence of a suspected antigen. The prototype antigen sought here was x‐casein, a frequent participant in immune complex formation in IgA deficiency and in atopic diseases. The enzyme‐antibody conjugate described here can detect as little as 0.11 ng/ml of x‐casein for immune complexes formed in vivo or in vitro, one can distinguish circulating complexes containing casein from complexes not containing this antigen. Using this reagent, a major antigen in the immune complexes of hypogamma‐globulinemic patients treated with intravenous γ‐globulin was unexpectedly identified as x‐casein. This method of specific immune complex analysis is suggested as a practical and effective approach to the elucidation of the antigenic constituents of immune complexes found in many diseases.