FIG. 1.

Effects of antibody isotypes and FcγR blocking antibody on MIP-1α production. Human microglia were exposed to C. neoformans plus MAb (3E5) bearing four different Fc fragments (γ1, γ2a, γ2b, and γ3) for 4 h, and then MIP-1α production was determined by ELISA. The results showed that MAbs bearing γ1, γ2a, and γ3, but not γ2b, induced MIP-1α production in microglia. In parallel cultures, human microglia were pretreated with Fab against human FcγRII (IV.3) or FcγRIII (3G8) for 30 min at 4°C and then incubated with C. neoformans plus MAb for an additional 16 h at 37°C. MIP-1α release was detected by ELISA. IV.3 had no effect on MIP-1α release, while 3G8 significantly inhibited MIP-1α release (P < 0.05 versus culture without blocking antibody). The experiments were repeated twice with similar results.