This project concerns an analysis of morphologic and functional properties of cells involved in synthesis of complement components; in particular phagocytic cells (macrophages) synthesizing the fourth component of complement (C4). By use of a modified Jerne plaque assay the numbers and types of cells involved in synthesis of complement components will be determined. Cells for examination will be harvested from peritoneal exudates induced in guinea pigs by a variety of agents which stimulate mild or severe exudates comprising either predominantly mononuclear or alternatively mixed inflammatory cellular elements. In addition, dissociated cells derived from liver or spleen, as well as pulmonary alveolar "macrophages" will be similarly examined for type and proportion of cells synthesizing the fourth component of complement. An alternative method for detection of cells with complement (C4) on immunohistochemical labeling of cells with horse-radish peroxidase coupled Fab fragemnts of anti-guinea pig C4 immunoglobulins. The number of cells in a particular inflammatory exudate with cell surface C4 will be compared to the number of cells in that exudate which can regenerate cell surface C4 after its removal by trypsin treatment. Of particular interest will be the effect of different injurious agents or events (chemical, microbial, immunologic, hypersensitivity) on the proportion of inflammatory cells, particularly mononuclear phagocytic cells, within an inflammatory exudate which are committed to synthesis of one or another complement component. BIBLIOGRAPHIC REFERENCES: Burkholder PM: Morphologic Basis for Classification of Glomerulonephritis. In: Glomerulonephritis, International Conference on Pathogenesis, Pathology, and Treatment. Edited by R Klutke, A Vogt, S Batsford, Stuttgart, Giorg Thieme Verlag, 1977. Moorthy AV, Zimmerman SW, Burkholder PM: Effects of Extrarenal Malignancies on the Kidney. In: Pediatric Renal Disease. In press, 1977.