POSSIBLE RELATIONSHIPS BETWEEN THE CYTOTOXIC EFFECTS OF ISOANTIBODY AND HOST CELL FUNCTION *

In vitro studies of ulcerative colitis. II. Cytotoxic action of white blood cells from patients on human fetal colon cells

Freshly isolated fetal human colon cells were labeled with (32)P-orthophosphate or (14)C-amino acids and exposed to white blood cells from children with ulcerative colitis or from healthy controls. Exposure of the colon cells to patients' white cells led to a rapid isotope release, significantly higher than that obtained with normal white cells. After 150 minutes of incubation, 75 per cent of the total isotope present was found in the media of the colitis samples but only 40 per cent in those of the controls. Consistent results were obtained with white blood cells from 14 patients and 18 healthy individuals. Similar results were obtained with either fresh white cells or with white cells aged for 12 to 18 hours and consisting to 60 to 70 per cent of lymphocytes and to 20 to 30 per cent of large mononuclear cells. No specific cytotoxic activity could be conferred onto normal white cells by pretreating them with patients' serum containing antibodies against colon antigen. The cytotoxic action of the patients' white cells was immunologically specific, since no difference from the controls was found in the isotope release when cells from other organs or animals were similarly treated. Preliminary experiments suggested that the patients' white cells could be desensitized by pretreating them with colon extract. For obtaining a significant cytotoxic effect of the patients' white cells, the presence of 10 to 20 per cent of fresh guinea pig or human serum in the incubation medium was required.

Passive transfer of transplantation immunity. I. Tritiated lymphoid cells. II. Lymphoid cells in millipore chambers

Passive transfer of tritiated thymidine labeled lymphoid cells sensitized to homologous tissues into non-sensitized isologous hosts resulted in accelerated rejection of homologous skin grafts in the recipients. Despite 33 per cent label of the suspension, only rare labeled sensitized lymphoid cells could be found at the site of rejection. Passive transfer of sensitized lymphoid cells in millipore chambers implanted subcutaneously or intraperitoneally in non-sensitized isologous hosts resulted in accelerated homograft rejection in the recipients. Transfer of transplantation immunity could not be accomplished with serum from sensitized hosts. The rejection of homologous tissues without the physical presence of the sensitized cell at the graft site suggested that a humoral agent produced by the cell was capable of rejecting the homograft.

The role of humoral antibodies in rejection of skin homografts in rabbits. II. Passive transfer of transplantation immunity by sensitized lymph node cells within diffusion chambers

Passive transfer of transplantation immunity by means of sensitized lymphoid cells enclosed within diffusion chambers has been accomplished in non-radiated and radiated rabbits. This result, together with other data available in the literature, suggests that humoral antibodies play an important role in rejection of skin homografts in the rabbit.

THE R OLE OF THE LARGE PERITONEAL MACROPHAGE IN TUMOUR HOMOGRAFT REJECTION

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Immunohistologic evidence for the role of antibody and macrophages in regression of the murine T1699 mammary adenocarcinoma

The regression or progression of the T1699 murine mammary adenocarcinoma was analyzed with histologic an immunohistologic techniques to determine the tissue distribution of both macrophages and anti-tumor antibody. Changes in integrity of tumor blood vessels were apparent during tumor growth and regression. Tumors at early stages of growth were invaded in the capsule by multiple vascular branches which later permeated tha tumor. Following the appearance of anti-tumor in the serum, these vessels often showed immune complex deposition which preceded vessel leakage, destruction and hemorrhage. After these changes, tumor cells appeared coated with antibody. Macrophages appeared predominantly in the tumor capsule during early stages of tumor growth, while at later stage they were observed within tumors most prominently near the edge of growing hemorrhagic and necrotic areas. As tumors regressed, connective tissue septation lined by macrophages became apparent. Phagocytosis of seemingly intact tumor cells was common and appeared to account for much of the loss in tumor cell numbers. In immunosuppressed animals (ATXBM,450R) in which tumor progression always occurred, the above features were markedly diminished or absent. This model emphasizes the interplay of many factors in tumor regression. These include immune complex deposition, blood vessel destruction, macrophage infiltration and connective tissue development, all of which are associated with tumor regression and seem to be infrequent and/or inconsequential during progressive tumor growth.

Rejection of ascites tumor allografts. I. Isolation, characterization, and in vitro reactivity of peritoneal lymphoid effector cells from BALB-c mice immune to EL4 leukosis

Peritoneal exudate cells (PEC), obtained after the rejection of EL4 leukemia by BALB/c mice, are much more effective in the specific in vitro destruction of (51)Cr-labeled EL4 cells than are spleen, thymus, lymph node, or peripheral blood lymphocytes. The presence of a large number of effector cells at the site of graft rejection is reflected in the potent cytolytic activity seen in vitro. Effector cells temporarily lose cytolytic reactivity when treated with trypsin but regain reactivity with time. This recovery occurs in normal as well as in immune serum. The destructive reactivity of PEC is increased when macrophages are removed. The remaining population of nonadherent PEC is composed primarily of small- to medium-sized lymphocytes. Complex tissue culture media are not needed, but there is a definite requirement for serum. The required serum component is heat stable, nondialyzable, and is not consumed during the reaction. The use of an ascites allograft system made these observations possible and permitted the isolation of those host cells intimately associated with rejection.