Gender, financial hardship, low education and vulnerability to stress, were regressed on a latent dependent variable representing covariances of three mitogen tests measuring immune response in the form of lymphocyte proliferation (CON-A, PHA, and PWM). In addition to the four main effects, six interaction terms involving all possible two-way combinations of the four main variables were regressed on the dependent variable. While financial strain and vulnerability exert significant negative main effects on immune response as anticipated, these variables interact with one another and with gender to produce complex conditional relationships. The interaction between low education and male gender produces a negative effect on immune response, while financial hardship and vulnerability to stress interact to produce positive effects on immune response. Copyright © 2000 John Wiley & Sons, Ltd.