Homogeneous populations of macrophages from histiocytic lymphoma patients as a source for macrophage subpopulations which differ in immunoregulatory properties

The existence of subpopulations of macrophages which express a variety of regulatory activities of other branches of the immune system is suggested in a comparative study of a human macrophage long term culture ZI and a macrophage cell line DAB‐1. Both cell cultures were derived from pleural effusions of patients with diffuse histiocytic lymphoma. DAB‐1 cells were found to secrete factors which strongly suppress the response of normal T and B lymphocytes to the mitogens PHA, Con‐A and pokeweed mitogen (PWM) (by 96–98%) and to stimulate the cytotoxic activity of NK cells.¹ ZI cells secrete factors which have a mild inhibitory effect on the response of lymphocytes to the T‐cell mitogens PHA and Con‐A and a stimulatory effect on the response to PWM, whereas very little effect could be detected on the activity of NK cells. While DAB‐1 cells form large clusters during growth in culture, and are capable of inducing the formation of lymphocyte rosettes around the tumor cells, ZI cells grow as a homogeneous monolayer and could not be shown to form such rosettes. The differences in the behavior of the two cell populations suggest that the malignant transformation may have affected different subsets of macrophages in each case. Cells from histiocytic lymphoma patients may therefore be a source for homogeneous subpopulations of macrophages and their isolation and propagation in culture is one approach by which such subsets can be defined characterized and classified. The biological characterization of macrophage subsets may also be of clinical importance since a transformed subset with broad suppressory activities may lead to a violent and rapidly deteriorating course of disease, as was in the case of the patient from whom the DAB‐1 cell line was derived. Cancer 50:69–77, 1982.