FIG. 1.

Lymphoproliferative responses of guinea pig or macaque spleen cells stimulated with PPD, at various times after rectal and intradermal administration of BCG. Spleen cells collected from guinea pigs (A) or macaques (B) nonimmunized (empty bars) or immunized with BCG via rectal (fine hatches) or intradermal (coarse hatches) routes were stimulated by incubation for 4 days in vitro with PPD (10 μg/ml). The SI were calculated as (counts per minute with PPD)/(counts per minute without PPD). Results in guinea pigs (n = 4) and macaques (n = 3) (geometric means of triplicate determinations [error bars, standard deviations]) are representative of two different experiments.