Antibody-dependent Cytolysis Research Articles

Regulation of Effector Functions of Human K‐Cells and Monocytes by Antigen Density of the Target Cells

Antibody-dependent cytolysis and phagocytosis mediated by human K-cells or monocytes against chicken erythrocytes (ChRBC) were studied. The antigen density of the target cells was varied by coating the cells with different amounts of 3H-labelled dinitrophenyl (DNP) hapten. The degree of antigenicity thus acquired by the target cells was assessed on the basis of their uptake of the isotope. Anti-DNP serum was used to induce lysis or phagocytosis. Below 500 antigenic determinants per ChRBC the target cells were not affected. However, at the density, lysis and/or phagocytosis was seen when the antibody concentration was high (2 X 10(-9) M). With less antibody present (2 X 10(-11) M) only monocyte-mediated phagocytosis was induced. The estimated lowest number of target-cell-bound antibodies required for K-cell-mediated lysis was approximately 50. The corresponding number for monocyte-mediated phagocytosis was approximately 20 IgG per ChRBC. The result suggests that interaction of several Fc receptors on the effector cells with IgG molecules bound to adjacent sites on the target cell membrane is an important factor in the regulation of these antibody-dependent cell-mediated effector functions.

Role of oxygen-dependent mechanisms in antibody-induced lysis of tumor cells by activated macrophages.

The alloantiserum-dependent lysis of TLX9 lymphoma cells by peritoneal cells from Bacille Calmette-Guerin (BCG)-treated mice was inhibited 62 percent by depletion of oxygen. This effect did not appear to be a result of interference with mitochondrial respiration because cyanide, azide, and dinitrophenol did not inhibit cytotoxicity. Preincubating the effector cells for 2 h without glucose, which markedly reduces their ability to release hydrogen peroxide, likewise suppressed antibody-dependent cytolysis by 62 percent. Lysis of sensitized lymphoma cells was virtually abolished by 6 mg/ml of thioglycollate broth, a concentration that also abrogated the detectable release of hydrogen peroxide and the lysis of lymphoma cells by BCG-activated macrophages in response to phorbol myristate acetate (PMA). This concentration of thioglycollate broth was not toxic to the effector cells, as judged by adherence to plastic, binding of opsonized erythrocytes, and phagocytosis of radiolabeled starch granules. Catalase, superoxide dismutase, horseradish peroxidase, mannitol, ethanol, benzoate, and diazabicyclooctane were without consistent effects. Cytochalasin B and dihydrocytochalasin B both markedly suppressed cytolysis, whether induced by antibody or by PMA (ID(50), 0.5 mug/ml). Cytoehalasin B was an equally potent suppressor of glucose uptake and PMA-induced hydrogen peroxide release by BCG-activated macrophages (ID(50), 0.5 mug/ml). However, dihydrocytochalasin B lacked these latter effects, which suggests that cytotoxicity required intact contractile elements. The extracellular lysis of antibody-coated lymphoma cells by BCG-activated macrophages appears to have a predominantly oxidative basis.

Antibodies to Tooth Allografts in H-2 Matched Mice

Teeth were transplanted among mice which represented the best match possible between unrelated humans. Sera were examined for their ability to kill donor cells with the help of complement, to trigger complement-independent, cell-mediated cytolysis, and to agglutinate RBC. All responses were weak, but rejection correlated best with antibody-dependent cytolysis.

Antibody-dependent cytolysis of Trypanosoma cruzi by human polymorphonuclear leukocytes

Human polymorphonuclear leukocytes were cytotoxic to Trypanosoma cruzi epimastigotes in the presence of specific antibodies from Chagas' disease patients and sera from rabbits immunized with homogenates of T. cruzi epimastigotes. Cytotoxicity was evaluated by the in vitro release of [ 3H]uridine-labeled RNA from culture forms. Under the same conditions, mononuclear cells were not cytotoxic. Pretreatment of target cells with antibodies was as effective as the continued presence of antisera during the reaction, while sera-treated effector cells did not mediate cytotoxicity. The cytotoxic effect depended on the concentration of effector cells and antibody and was progressive until 4 hr of incubation at 28 °C.

Antibody-Dependent Lysis of Tumor Cells In Vivo. II. Elimination of Chromium-51 as a Measurement of Cytolysis<xref ref-type="fn" rid="FN1">2</xref><xref ref-type="fn" rid="FN2">3</xref>

The effect of antibody on tumor cells was studied in vivo by measurement of the rate of elimination of 51Cr in A/J mice inoculated with labeled Ehrlich tumor cells. Mice receiving ip injections of tumor cells and normal serum eliminated 51Cr rapidly during the first 24 hours and at a much slower rate thereafter. This biphasic pattern of elimination was due to the fact that 51Cr predominantly labels small (less than 13,000 mol wt) intracellular molecules, which the mouse rapidly eliminates, whereas larger labeled molecules are eliminated slowly. Antibody to tumor cells significantly accelerated the elimination of 51Cr at concentrations that regularly suppressed tumor growth. Antibody also induced a faster elimination rate in mice treated with cobra venom factor but not in mice treated with silica or inoculated sc with the tumor cells. Unlabeled tumor cells inhibited antibody-induced 51Cr clearance in normal mice but not in proteose peptone-treated mice. These results suggested that peritoneal cells are required in the induction of antibody-dependent cytolysis in vivo. In addition, actively or passively alloimmunized mice exhibited a similar accelerated 51Cr elimination rate when inoculated with the appropriate labeled target cells.

Lymphocyte-Mediated Antibody-Dependent Cytolysis: Role in Immune Hemolysis

Peripheral blood lymphocytes obtained from normal volunteers were capable of lysing Rh(D)-positive human erythrocytes in the presence of IgG anti-Rh(D) antibodies. The percent cytotoxicity produced by peripheral blood lymphocytes was approximately equivalent to that produced by unfractionated peripheral blood mononuclear cells. Neither peripheral blood mononuclear cells nor peripheral blood lymphocytes lysed Rh(D)-negative human erythrocytes in the presence of IgG anti-Rh(D) antibody.

Antibody-Dependent Cytolysis of Chicken Erythrocytes by an in Vitro-Established Line of Mouse Peritoneal Macrophages

An in vitro-established line of mouse peritoneal macrophages (IC-21) was tested for its ability to mediate the cytolysis of 51chromiun-labeled chicken erythrocytes. In the presence of specific antibody, but independently of complement, the macrophages phagocytized and lysed labeled erythrocytes. The phagocytic process proved to be functionally distinct from the cytolytic reaction as demonstrated by enhanced cytolysis in the presence of iodoacetate, an inhibitor of phagocytosis. This cell line, because of its effector activity in antibody-dependent cell-mediated immune reactions, will be useful in characterizing the mechanism(s) involved in macrophage-mediated cytolysis.

Cytolytic lymphocytic cells with complement receptor in human blood. Induction of cytolysis by IgG antibody but not by target cell-bound C3.

Human blood lymphocytes were fractionated on glass bead columns charged with sheep erythrocyte (Es) membranes-bearing human C3b (7,000-10,000 molecules/Es). In the passaged cells the proportion of C receptor lymphocytes was strongly reduced, in parallel with the capacity to lyse chicken erythrocytes (Ec) in the presence of IgG-rabbit anti-Ec antibody. In other experiments, lymphocytes forming rosettes with Es bearing activated rabbit complement [C(ra)] from C6-deficient rabbits were removed by centrifugation through human serum albumin-gelatine mixtures. This procedure also depleted the lymphocyte preparations of antibody-dependent cytolytic effector cells. The results suggest that rations of antibody-dependent cytolytic effector cells. The result suggest that such effector cells have receptors for human C as well as for C(ra). Lymphocytes were not able to lyse erythrocytes bearing either human C3b (similar to 30,000 molecules/Ec) or activated C(ra) in the absence if IgG antierythrocyte antibodies. Under the same experimental conditions these target cells were efficiently lysed in the presence of small amounts of IgG antitarget cell antibodies. This suggests that the interaction between the cellular Fcreceptors and the Fc part of the inducing antibodies is of special significance for the triggering of the cell-mediated lytic reaction. However, although target cell-bound C did not trigger cytolysis, it seemed to potentiate antibody-dependent cytolysis, probably by enhancing effector cell-target cell contacts.