Immune System and Intergroup Bias: Vaccine-Induced Increases in Cytokine Activity Are Associated with Worse Evaluations of Resume for Latina Job Applicant

In the present research, we drew on literature in psychoneuroimmunology (PNI) to propose that a hitherto unexplored but potentially important situational factor that may increase intergroup bias is illness and acute inflammation. To examine whether acute inflammation, quantified by increases in salivary cytokines, would lead to greater intergroup bias, we conducted an experiment using a protocol adapted from PNI that increases cytokines via administration of the seasonal influenza vaccine (or saline placebo). Our measures of intergroup bias were a resume evaluation task and an ethnocentrism questionnaire. Providing support for our hypothesis, increases in the cytokine interleukin-1beta were positively associated with intergroup bias. Specifically, participants who experienced greater (vs. lesser) increases in interleukin-1beta rated a Latina applicant as less competent and recommended that she receive a lower starting salary, and demonstrated higher ethnocentrism. Overall, results provide first direct evidence that experimental inductions of immune activity contribute to intergroup bias.