Gender differences in response to the Multitest CMI skin test in the general population

Background: Previous studies of gender differences in response to the Multitest CMI skin test have produced conflicting results. Objective: To determine whether gender is associated with response to the Multitest CMI skin test. Methods: Two-hundred ninety-seven adults, aged 18 to 64 years, recruited originally for a study of the immune effects associated with living near a hazardous waste site containing primarily organochlorine pesticides, underwent a skin test using the Multitest CMI skin test. Six of seven antigens were tested: tetanus toroid, diphtheria toroid, Candida, Tricophyton, Streptococcus, and Proteus. The tuberculin antigen was excluded. Lymphocyte function was also evaluated in vitro using standardized methods of mitogen stimulation with phytohemaglutinin (PHA), concanavalin A (CON-A), and pokeweed mitogen. Results: The frequency of positive responses to the skin tests was significantly (P < .001) higher among males (80.4%) than among females (55.7%). Males were more likely than females to respond to all six antigens tested (P < .05). The mean diameter of positive skin test measurements for males statistically significantly (P < .05) exceeded female responses for tetanus and diphtheria. Although not statistically significant, male response size exceeded that of females for all other antigens except Trycophyton. Controlling for age, race, smoking, income, and plasma DDE levels did not change these results. Skin test positivity was not associated with mitogen stimulation assay results overall or within gender groups. Conclusion: Significant gender differences in response to the Multitest CMI skin test could limit its use as a marker of anergy in general population studies.