Macrophage-related skin test reactivity in normal and tumor-bearing hosts

The macrophage-activating substances pyran and glucan were used to initiate studies of macrophage activity in vivo. Skin tests were performed using graded doses of each of these reagents. Skin test responses (mm induration) were correlated with tumor growth, α-2-macroglobulin levels and the histology of the skin test site in normal and immunosuppressed tumor-bearing guinea pigs. An almost pure tissue macrophage infiltrate resulted from the injection of pyran and glucan. In addition, there was a clear correlation between tumor-bearing and diminished skin test responses. It would seem that the chemotactic effects of these agents bypass other possibly immunologic effects and that both pyran and glucan are, therefore, able to produce a skin test response despite the state of immunosuppression associated with progressive cancer growth. These findings may serve as a model for methods to study skin anergy in cancer patients.