In vitro delayed hypersensitivity in normal and hyporeactive patients.

Overview

The in vitro macrophage migration inhibition test can be used to evaluate human delayed hypersensitivity. Using purified protein derivative of tuberculin (PPD) as the antigen, twenty of twenty-seven in vitro tests in non-anergic persons with negative PPD skin tests were negative and fifteen of sixteen in vitro tests in persons with positive skin tests were positive. In patients with drug or disease-induced cutaneous hyporeactivity, twelve of twenty-eight tests were positive despite negative skin tests. In two anergic patients with mucocutaneous candidiasis positive in vitro tests were obtained with Candida albicans antigen as well. Measurable levels of IgG were seldom detected in the test media. The results indicate that the macrophage migration inhibition test measures delayed hypersensitivity in man and is sometimes positive in cases of reduced skin reactivity.