Figure 1.

Total and Cryptococcus neoformans-specific IgG and IgM antibodies differ between quenchable sera from cryptococcal meningitis patients and healthy controls. Human sera from patients with cryptococcal meningitis (CM), either HIV-positive (HIV+) or HIV-negative (HIV-), and healthy control persons were analyzed. Concentration of (A) total serum IgG antibodies was similar in all groups, whereas concentration of (B) total serum IgM antibodies was increased in the healthy Colombian control group. C. neoformans-specific antibodies directed against intact cryptococcal cells (anti-Cn) (C) IgG or (D) IgM antibodies were quantified using flow cytometry. Median fluorescent intensity (MFI) was similar for anti-Cn IgG antibodies in all groups, but significantly enhanced for anti-Cn IgM antibodies in healthy control persons. Titers of (E) IgG and (F) IgM directed capsular polysaccharides (CPS) as well as titers of (G) IgG and (H) IgM directed against cryptococcal proteins were determined using ELISA. Titers of anti-CPS IgG and anti-protein IgG were increased in HIV-negative CM patients compared to HIV-positive CM patients and healthy control persons, whereas titers of anti-CPS IgM and anti-protein IgM were similar between all groups. Each dot represents an individual serum and lines indicate median values. Statistical analysis was carried out using the Mann–Whitney U test for comparison of two groups. Asterisks indicate significant difference.