Macrophage Hybridomas: An Approach to the Analysis of the Functional Heterogeneity of Macrophages

Abstract

Macrophages are wandering phagocytic cells known to participate in a wide variety of immunological processes, including phagocytosis, antigen presentation and cytostasis or killing of tumor cells. Despite their seemingly common histological origin, they do not consist of a homogeneous population. Macrophages seem to differ in morphology, expression of membrane markers (H-2I, Fc and C3 receptors), enzymatic contents and biological activities. Our previous studies concerning control and immunogenic properties of distinct subpopulations of macrophages revealed the existence of two major subpopulations, only one of which was highly efficient in presenting antigen to specific T lymphocytes (1). The other subpopulation, while highly phagocytic, was devoid of antigen-presenting capacity (1). The heterogeneity of cell types, the inability of macrophages to grow in culture, particularly as cloned populations, and the limitations of the methods for separation of distinct macrophage subpopulations do not enable a precise and detailed analysis of the molecular mechanisms and controlling signals which regulate the biological activity (i.e., phagocytosis, chemotaxis, secretion of interleukin 1, antigen presentation) in correlation to membrane molecules which characterize defined subsets of macrophages.