IMMUNE-COMPLEX RECEPTORS ON CELL-SURFACES .2. CYTOCHEMICAL EVALUATION OF THEIR ABUNDANCE ON DIFFERENT IMMUNE CELLS - DISTRIBUTION, UPTAKE, AND REGENERATION

  • 1 January 1976
    • journal article
    • research article
    • Vol. 84  (3) , 437-+
Abstract
A recently developed method for ultrastructural demonstration of cell surface receptors for immune complexes is applied to evaluation of these receptors on various [rabbit] cell types. The method entailing incubation with a complex of horseradish peroxidase (HRP) and antibody to HRP (anti-HRP) disclosed dense foci indicative of immune complex receptors distributed at 30- to 120-m.mu. intervals over macrophage surfaces. Invaginations, loop-like evaginations and pinocytotic vesicles stained prominently. The number of stained immune complex receptors averaged 200,000 per oil-induced macrophage and 120,000 per noninduced macrophage, as determined from counts of focal deposits in electron micrographs. Receptor periodicity on giant cells present in oil-induced exudates resembled periodicity on macrophages, but the larger giant cells contained an estimated 1.5 million sites. Although receptor periodicity on eosinophils and neutrophils equaled that on macrophages, the staining was lighter and was interrupted by intervals of unstained membrane. Neutrophils averaged 28,000 and eosinophils 35,000 receptors/cell; those lymphocytes with receptors averaged 3500/cell. Viable cells incubated with anti-HRP and HRP sequentially exhibited about 1/2 as many reactive sites as did cells incubated with immune complex. When warmed to 37.degree. C, viable macrophages and eosinophils pinocytosed soluble immune complexes almost completely within 30 min and phagocytosed insoluble complexes more slowly. The endocytosed soluble immune complexes were sequestered within tubulovesicular structures in addition to the expected phagocytic vacuoles. Receptors appeared fully active on macrophages that were restrained with soluble, cold immune complex after they had endocytosed immune complex in the course of a 30-min warming interval.