FIG. 3.

Preincubation of C. neoformans 67 in purified CPS reduced phagocytosis and decreased lymphocyte proliferation. (A) PBMC (2 × 10⁵/well) were put into culture with various numbers of untreated, acapsular C. neoformans cells (□) or acapsular C. neoformans cells that had been pretreated with purified CPS (■). Eighteen hours later, coverslips were examined for the percentage of cells that had phagocytosed C. neoformans (Crypto). (B) In parallel, the proliferative responses of PBMC (2 × 10⁵/well) stimulated with various numbers of untreated C. neoformans cells (□) and with C. neoformans that had been treated with purified CPS (■) were compared. After 7 days, lymphocyte proliferation was assessed by [³H]TdR incorporation. The experiment was repeated twice with similar results. ∗, P < 0.01 compared to untreated organisms. E:T, effector/target.