IFN-γ production and lymphoproliferative responses to malaria antigens are inhibited in WBAs. PBMCs (10⁶/mL) and 1:10 diluted whole-blood assays (WBAs) derived from single blood samples were incubated for 7 days with PHA (5 μg/mL), PPD (5 μg/mL), 5 × 10⁵/mL iRBCs, 5 × 10⁵/mL PfSL, 5 × 10⁵/mL uninfected red blood cells (uRBCs), or growth medium only (GM). IFN-γ (A) was assayed by ELISA in 6-day supernatants, and lymphoproliferation (B) was assessed after 7 days. In each column, the filled symbols on the left represent values obtained from PBMC assays, and the open symbols on the right represent values obtained from WBAs; each point represents data from one donor. Two donors had previous exposure to malaria (donor nos. 1, and ⋄; and 3, ▪ and □), and 3 donors were malaria nonexposed (donor nos. 7, • and ○; 4, ^*; and 5, ▴ and ▵).The lower limit of detection for the IFN-γ ELISA (125 pg/mL) (A) and the background level of [³H] incorporation (B) are indicated by dotted lines.