Immunologic Competence and Phagocytosis in Germfree Animals With and Without Stress

Abstract

The STRUCTURE and function of lymphatic tissue are known to be influenced by the microbial flora. The bacteria of the external environment and the intestine are the major source of such stimuli even under "normal" circumstances. In order to evaluate the role of the microflora in lymphatic tissue reactions, a study was undertaken of lymph nodes and spleens of animals which had never been exposed to living microorganisms. Since the development of germfree techniques,^1,2 germfree animals have become available for comparative studies of the structure and function of lymphatic tissue and its reactions to injury. The experiments reported here include a comparison of those lymph nodes which in conventional animals drain organs rich in bacteria, such as the pharynx, larynx, and intestinal tract, with nodes from the extremities which are usually not exposed to microorganisms. Previous studies in animals not subjected to stress were supplemented by recent observations of