The major objective of the proposed research is to further the role of humoral and cellular components of the host defense mechanism in the human response to both thermal and non-thermal life-threatening trauma. The fixed cells of the reticuloendothelial system and the peripheral circulating lymphocytes will be specifically studied. Serum, tissues, and infecting bacteria obtained from selected patients will be analyzed for their effect upon the phagocytic capacity of the RES and the blastogenic and specific and non-specific antibody-producing responses of the phagocytic capacity will be directly measured. Significant changes in the above test systems will be correlated, if possible, with the clinical responses of the patients studied. If significant effector substances are identifiable utilizing the planned techniques, attempts will be made to devise clinically applicable techniques to measure these substances as a guide to prognosis and therapy.