Infectious allergy.

The allergic reactivity which accompanies various infectious diseases is different in certain fundamental principles from the allergic disease associated with hypersensitivity to such agents as pollens, dust, and foods. Allergic sensitivity associated with tuberculosis comes about because of the participation of a fatty fraction of the bacillus with another component of the bacterium which is acutally the sensitizing substance. The fatty fraction, if isolated from the bacillus, can act with various kinds of sensitizing substances that have nothing to do with tuberculosis to bring about the same kind of hypersensitivity that accompanies tuberculosis. Attempts are being made to learn more about the manner of action of this factor, and also to find out whether the organisms of other infectious diseases may have similar chemical constituents that cause allergic disease.