FIG. 2.

Lymphocyte proliferation in response to acapsular C. neoformans 67 was abrogated when the organism was preincubated in purified polysaccharide. PBMC alone (□) were compared to PBMC that were stimulated with C. neoformans (■); PBMC that were stimulated with C. neoformans in the presence of 10 μg of CPS per ml (); PBMC that were pretreated for 1 h at 37°C (Tx’d) with CPS, washed, and stimulated with C. neoformans ( ); or C. neoformans that was pretreated for 1 h at 37°C with CPS, washed, and used to stimulate PBMC (▤). After 7 days, lymphocyte proliferation was determined by [³H]TdR incorporation. ∗, P < 0.05 compared to unstimulated PBMC. NS, not significantly different compared to C. neoformans-stimulated PBMC. †, P < 0.05 compared to stimulated PBMC. The experiment was repeated four times with similar results.