Electron Microscopic Study of Inhibition of Macrophage Migration in Delayed Hypersensitivity

Abstract

Abstract The migration of peritoneal cells from guinea pigs with delayed hypersensitivity to bacillus Calmette-Guérin was studied by light and electron microscopy. To permit satisfactory morphologic study and monitoring of cell migration, cells were concentrated in clots whose open interstices were accessible to medium. This clot technique, compared to the commonly used capillary tube, provided: 1) better viability and more uniform morphology, 2) better sampling for electron microscopy, 3) more uniform exposure to antigen, and 4) the opportunity to use fewer cells. Suspension cultures of spleen cells were also examined. among peritoneal exudate cells from sensitized animals, purified protein derivative (PPD) induced clumping of macrophages, an increase in the number of their microvilli, and some cell death. Many of the clumped cells bore numerous microvilli which intertwined with those of contiguous cells. No intracellular differences between sensitized and control macrophages or lymphocytes, exposed or not exposed to antigen, were discernible. Sensitized cells exposed to PPD in suspension cultures were disc-shaped and clumped. Control cells were flattened on the flask floor, angulated and usually separated. We believe that both the rounded form of the macrophages and their clumping may contribute to the lack of migration.