Opsonic requirements for the uptake of cryptococcus neoformans by human polymorphonuclear leukocytes and monocytes

Chemiluminescence was used to determine opsonic requirements for interaction of Cryptococcus neoformans with human peripheral blood polymorphonuclear leukocytes (PMNLs) and monocytes (MNs). Peak chemiluminescence (mean ± SD) was 172 ± 25 x 103 for PMNLs and 50 ± 13 x 103 for MNs with 20070 pooled normal human serum vs. 10 ± 3 x 103 for PMNLs and 6 ± 1 x 103 for MNs without serum (P < 0.005 for each comparison). The nature of the serum requirement was investigated; alternative pathway serum complement components were necessary. The alternative pathway was activated directly by C. neoformans without the need for specific antibody. Chemiluminescence provided a quantitative and reproducible assay of the interaction of human phagocytes with C. neoformans and may be useful in studying opsonic requirements of other fungi.