The course of cryptococcal capsular polysaccharide antigenemia/human cryptococcal polysaccharide elimination kinetics

The detection of cryptococcal polysaccharides in the serum is diagnostic of cryptococcosis in the absence of rheumatoid factor. The significance of the continued detection of this antigen in the serum during antifungal therapy is not known. Prolonged antigenemia might indicate ongoing active infection, delayed clearance of the polysaccharides from the blood, or continued release of the polysaccharide antigens from a reservoir of nonviable organisms. In seven cases the cryptococcosis with prolonged and high levels of cryptococcal polysaccharide antigenemia, the courses of antigenemia were determined. During the convalescent phase, the T 1/2's were approximately 48 hours for the antigen clearance in all the cases studied. The polysaccharide antigens recovered from the serum of one patient had molecular weights of greater than 200,000 daltons. In rabbits, a single intravenous injection of cryptococcal capsular polysaccharides showed a similarly slow clearance of the antigen with a T 1/2 of approximately 24 to 48 hours. These data suggest that adequately treated cases of cryptococcosis may have a predictable rate of antigen clearance from the serum during convalescence.