Combination of Conventional and Endotoxin-Specific Limulus Tests for Measurement of Polysaccharides in Sera of Rabbits with Experimental Systemic Candidiasis

Factor G, the coagulation enzyme from limulus amebocytes, is activated by (1→3)-β-D-glucan but not by endotoxin. The endotoxin-specific limulus test, which is devoid of fator G, reacts only with endotoxin. However, the conventional limulus test which includes factors G and C, reacts with not only endotoxin but also with (1→3)-β-D-glucan. In this study, the culture supernatant of Candida albicans in RPMI medium activated the conventional limulus test, but not the endotoxin-specific limulus test. All five rabbits inoculated intravenously with Candida albicans (1.0×107 CFU/rabbit) showed increased levels of reactivity with the conventional limulus test, whereas no elevation in the levels of the endotoxin-specific limulus test was observed in the sera of any infected rabbits. Only one serum sample from rabbit No. 5 on day 8 showed a positive Cand-tectest. The difference in the titers of the two limulus tests was suggestive of a diagnosis of Candida infection.-limulus test; serological diagnosis; β-glucan; polysaccharide; candidiasis.