Rapid clearance of Candida albicans mannan antigens by liver and spleen in contrast to prolonged circulation of Cryptococcus neoformans antigens

Abstract

Clearances of mannan antigen from Candida albicans and glucuronoxylomannan antigen from Cryptococcus neoformans were examined in nonimmune rabbits by using self-prepared latex agglutination tests. Injected intravenously, 20 mg of Candida mannan antigen was cleared from the serum with a half-life of approximately 2 h. In contrast, 20 micrograms of Cryptococcus glucuronoxylomannan antigen had a half-life in serum of approximately 24 h. At the latest, 9 h after injection, both antigens were no longer detectable without pretreatment of serum samples with protease and heating to 100 degrees C, thus indicating rapid binding by serum proteins other than immunoglobulins. Candida mannan antigen clearance was also examined in nonimmune mice after intravenous injection of (i) 200 micrograms of Candida mannan antigen, which accumulated in the liver and spleen and persisted for 97 days; (ii) 2 x 10(7) ethanol-killed Candida blastospores, which was accompanied by rapid clearance of mannan from the blood but accumulation of mannan in the liver and spleen and slow clearance from these organs; (iii) 6 x 10(6) viable C. albicans cells (lethal infection), which resulted in a rapid decrease of Candida CFU in the blood, liver, and spleen during the first 8 h, after which blood cultures were negative on day 2 and viable Candida burdens in the liver and spleen persisted at 10(5) CFU/g, whereas Candida mannan antigen continued to circulate in the bloodstream and accumulated in the liver and spleen.