Anti-mannan was produced in rabbits after peptidoglucomannan in adjuvant was injected. The antiserum was used to detect mannan by immunodiffusion and counterimmunoelectrophoresis (CIE) in gel and by sandwich enzyme-linked immunosorbent assay (ELISA). The antiserum detected lower concentrations of mannan of serotype A than of serotype B. Except in CIE, the reactions were more pronounced at 4 degrees C than at higher temperatures. CIE detected 0.8 microgram/ml mannan A or 12.5 microgram/ml mannan B. Sandwich ELISA detected 3 ng/ml mannan A or 10(5) ng/ml mannan B. Mannan was not detected in the serum of patients or rabbits with candidiasis.