PBMC from HIV-infected individuals are deficient in the p40 response to C albicans. Freshly harvested yeast cells of strain CA-6 or PCA-2 were washed twice in 1 × PBS and cultured for 24 hours with 2 × 10⁶/mL PBMC from control subjects or patients. Tests were conducted to find optimal culture conditions for the use of yeast cells: heat-inactivation at 65°C for 1 hour (heat killed) before addition to culture at a 1:2 yeast cell:PBMC ratio was found to be a more effective IL-12–stimulus than addition of live C albicans. Cell-free supernatants were assayed for p40 content via RIA. n = 16 for HIV⁺ group and n = 7 for HIV⁻group. Bars represent means of each cohort; P values were calculated via an unpaired student’s t-test and compared HIV⁺ (░) and HIV⁻ (□) groups for each condition; error bars indicate SEM.