J774 MURINE MACROPHAGE-LIKE CELL-INTERACTIONS WITH CRYPTOCOCCUS-NEOFORMANS IN THE PRESENCE AND ABSENCE OF OPSONINS

The interaction of Cryptococcus neoformans with the murine macrophage- like cell line J774.16 was studied in the presence and absence of mono clonal antibodies (MAbs) to the capsular polysaccharide glucuronoxylom annan (GXM). In the absence of MAb 2H1 to GXM, coincubation of J774.16 cells with C. neoformans reduced fungal colony-forming units in only 26.6% of 21 independent experiments, In the presence of MAb 2H1, coinc ubation of J774.16 cells with C. neoformans reduced fungal colony-form ing units in > 95% of experiments, Comparison of the relative efficacy of two IgG1 MAbs revealed that the higher affinity MAb was more effec tive at low concentrations. Antibody-mediated reductions of C. neoform ans colony-forming units by J774.16 cells occurred despite inhibition of nitric oxide synthase, addition of reactive oxygen intermediate sca vengers, or the use of a superoxide-deficient J774 mutant line.