Race and sex-based differences in cytokine immune responses to smallpox vaccine in healthy individuals

We assessed the effects of sex, race and ethnicity on smallpox vaccine-induced immune responses in 1071 armed forces members after primary Dryvax® smallpox vaccination, including 790 males and 281 females; 580 Caucasians, 217 African-Americans, and 217 Hispanics. Analysis of vaccinia-specific cytokine responses revealed that Caucasians had higher total IFNγ ELISPOT responses (median 57 spot-forming units/SFUs per 200,000 cells, p = 0.01) and CD8+IFNγ ELISPOT responses (12 SFUs, p < 0.001) than African-Americans (51 and 4 SFUs, respectively) and Hispanics (47 and 8 SFUs, respectively). Similarly, Caucasians secreted higher levels of vaccinia-specific IL-2 (p = 0.003) and IFNα (p < 0.001) compared to other racial/ethnic groups. Males had higher total IFNγ ELISPOT responses (median 55 SFUs) compared to females (41 SFUs, p < 0.001). We observed statistically significant sex-related differences in the secretion of IL-2 (p < 0.001), IL-1β (p < 0.001) and IL-10 (p = 0.017). These data suggest that vaccinia-specific cytokine responses following primary smallpox vaccination are significantly influenced by race and sex of vaccinees.