Interaction of macrophages and lymphocytes with surface immunoglobulin

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. 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 violet and rapidly deteriorating course of disease, as was in the case of the patient from whom the DAB-1 cell line was derived.

Reduced monocyte phagocytosis in patients with advanced Hodgkin's disease and lymphosarcoma

The monocytes of 7 patients with advanced Hdgkin's disease (stages III and IV) and of two patients with generalized lymphosarcoma exhibited a highly significant impairment of the phagocytosis of IgG-coated red cells, regardless of receiving therapy or not. In contrast three patients with M. Hodgkin, stage II B, and one with lymphosarcoma in complete remission showed a rather elevated monocyte phagocytic acitivity. The nitroblue tetrazolium reduction by monocytes in the mean was significantly enhanced in all patients investigated, compared with normal persons, although only in one patient a bacterial infection was apparent at the time of the test. The possible implication of the findings in the well known immunodeficiency present in M. Hodgkin and lymphosarcoma is discussed.

Macrophage-lymphocyte interaction. I. Characteristics of the antigen-independent-binding of guinea pig thymocytes and lymphocytes to syngeneic macrophages

The nature of the physical interaction between guinea pig non-glass-adherent lymphoid cells and syngeneic macrophages in vitro was investigated. This cellular interaction was found to require the presence of metabolically intact macrophages but neither serum nor antigen. Peritoneal, splenic, or alveolar macrophages were significantly more capable of interacting with thymocytes than either polymorphonuclear leukocytes or fibroblasts. The role of the non-glass-adherent cell was passive in that heat-killed or metabolically poisoned thymocytes were bound by normal macrophages. Two normal lymphoid cell populations, thymocytes, and lymph node lymphocytes, were bound to macrophages in significantly larger numbers than either L(2)C leukemia cells or erythrocytes. Thus, specificity for each of the participant cell types was demonstrated. These data indicate that macrophages possess a unique ability to recognize and bind lymphocytes and thymocytes by a mechanism which is distinguishable from other known macrophage receptors.

Cell interactions in the immune response in vitro. V. Specific collaboration via complexes of antigen and thymus-derived cell immunoglobulin

The mechanism of interaction of T and B lymphocytes was investigated in an in vitro hapten carrier system using culture chambers with two compartments separated by a cell impermeable nucleopore membrane. Because specific cell interaction occurred efficiently across this membrane, contact of T and B lymphocytes was not essential for cooperation which must have been mediated by a subcellular component or "factor." By using different lymphoid cell populations in the lower culture chamber and activated thymus cells in the upper chamber (with antigen present in both), it was found that the antigen-specific mediator acted indirectly on B cells, through the agency of macrophages. Macrophages which had been cultured in the presence of activated T cells and antigen acquired the capacity to specifically induce antibody responses in B cell-containing lymphoid populations. Trypsinization of these macrophages inhibited their capacity to induce immune responses, indicating that the mediator of cell cooperation is membrane bound. By using antisera to both the haptenic and carrier determinants of the antigen as blocking reagents, it was demonstrated that the whole antigen molecule was present on the surface of macrophages which had been exposed to activated T cells and antigen. Because specifically activated T cells were essential a component of the antigen-specific mediator must be derived from these cells. By using anti-immunoglobulin sera as inhibitors of the binding of the mediator to macrophages, the T cell component was indeed found to contain both kappa- and micro-chains and was thus presumably a T cell-derived immunoglobulin. It was proposed that cell cooperation is mediated by complexes of T cell IgM and antigen, bound to the surface of macrophage-like cells, forming a lattice of appropriately spaced antigenic determinants. B cells become immunized by interacting with this surface. With this mechanism of cell cooperation, the actual pattern of antigen-B cell receptor interactions in immunization would be the same with both thymus-dependent and independent antigens. An essential feature of the proposed mechanism of cell cooperation is that macrophage-B cell interaction must occur at an early stage of the antibody response, a concept which is supported by many lines of evidence. Furthermore this mechanism of cell interaction can be elaborated to explain certain phenomena such as the highly immunogenic macrophage-bound antigen, antigenic competition, the distinction between immunity and tolerance in B lymphocytes, and the possible mediation of tolerance by T lymphocytes.

Cell interactions in the immune response in vitro. 3. Specific collaboration across a cell impermeable membrane

Tissue cultures with two compartments, separated by a cell impermeable nuclepore membrane (1 micro pore size), were used to investigate the mechanism of T-B lymphocyte cooperation. It was found that collaboration was as effective when the T and B lymphocyte populations were separated by the membrane as when they were mixed together. Critical tests were performed to verify that the membranes used were in fact cell impermeable. The specificity of the augmentation of the B cell response by various T cell populations was investigated. Only the response of B cells reactive to determinants on the same molecule as recognized by the T cells was augmented markedly. Specific activation of thymocytes by antigen was necessary for efficient collaboration across the membrane. The response of both unprimed and hapten-primed spleen cells was augmented by the T cell "factor" although, as expected, hapten-primed cells yielded greater responses. The T cell factor acted as efficiently if T cells were present or absent in the lower chamber. Thus the site of action of the T cell factor was not on other T cells, but was either on macrophages or the B cells themselves. The T cell-specific immunizing factor did not pass through dialysis membranes. The experiments reported here help rule out some of the possible theories of T-B cell collaboration. Clearly T-B cell contact was not necessary for successful cooperation to occur in this system. Possible theoretical interpretations of the results and their bearing on the detailed mechanism of T-B lymphocyte cooperation are discussed.