Identification of components of IC purified from human sera. II. Demonstration of mycobacterial antigens in immune complexes isolated from sera of lepromatous patients.

Immune complexes have been purified from sera of patients with lepromatous leprosy, using solid phase conglutinin and analysed by SDS-PAGE. Some of their components have been immunologically identified after electrophoretic blotting on nitrocellulose. First, immunoglobulins, complement components (C1q, C1s, C3) and CRP were found in IC. Secondly, one mycobacterial antigen of 67 kD was directly identified in IC while two other components (20 kD and 14.4 kD) of possible M. leprae origin were also found in IC. This study suggests that lepromatous patients develop a good antibody response against some M. leprae antigens (33 kD and 12 kD), which are rapidly eliminated from circulation, while other M. leprae antigens (e.g. 67 kD) can persist in relative antigen excess, within circulating IC.