Monocyte Antibody-dependent Cell-mediated Cytotoxicity Research Articles

In vitro functional activity of IgG1 and IgG3 polyclonal and monoclonal anti-D.

IgG anti-D is generally restricted to IgG1 and IgG3; it mediates red cell destruction through interactions with IgG Fc receptors (Fc gamma R) on effector cells. The relative ability of these two IgG subclasses of anti-D to mediate haemolysis in vitro by monocytes and K cells was investigated. Anti-D was affinity purified from 5 preparations of prophylactic anti-D immunoglobulin, and IgG subclasses quantified by ELISA; mean levels were 86.5% IgG1, 1.4% IgG2, 11.6% IgG3 and 0.4% IgG4. IgG1 and IgG3 polyclonal anti-D were further purified separately from some of the anti-D by removal of either IgG3 using magnetic beads coated with anti-IgG3, or of IgG1 using protein A. These preparations were compared with monoclonal anti-D (BRAD-3 and BRAD-5) for their ability to lyse red cells in antibody-dependent cell-mediated cytotoxicity (ADCC) assays. Monocyte-mediated lysis of red cells coated with IgG3 anti-D was approximately twice that of cells coated with IgG1 anti-D at similar sensitization levels, and anti-D preparations containing 10% or more IgG3 gave similar lysis. By contrast, in the K cell ADCC, IgG1 anti-D was 2-4 times more haemolytic than IgG3 anti-D. Polyclonal IgG1 and IgG3 anti-D promoted about 20% more lysis than BRAD-5 (IgG1) and BRAD-3 (IgG3), respectively, in the K cell ADCC, although no difference was observed between polyclonal and monoclonal anti-D in the monocyte ADCC. These experiments demonstrated a functional dichotomy between these two subclasses of anti-D; IgG3-coated red cells were lysed preferentially by monocytes mediated predominantly through Fc gamma R1 interactions, whereas haemolysis of IgG1-sensitized cells was mediated mainly by Fc gamma RIII on K cells.

Mononuclear phagocyte assays, autoanalyzer quantitation and IgG subclasses of maternal anti-RhD in the prediction of the severity of haemolytic disease in the fetus before 32 weeks gestation.

In 40 cases of haemolytic disease of the fetus due to RhD immunization where the fetus required intrauterine transfusion, fetal packed cell volume was compared with the following parameters of maternal anti-D: (a) concentration, (b) IgG subclass, (c) activity in a macrophage binding assay, and (d) activity in a monocyte antibody-dependent cell mediated cytotoxicity (ADCC) assay. The anti-D concentration exceeded 4 iu/ml in all cases, correctly indicating the risk of haemolytic disease. A relationship between IgG subclass composition of the anti-D and severity of anaemia was not observed; IgG1, IgG3 and IgG1 + 3 antibodies were all detected. The ADCC assay gave the best correlation between assay results and fetal packed cell volume; high results correctly indicated fetal anaemia in 95% of cases. Macrophage binding assay results were only considered as high in 70% of cases. Overall, these results indicate that serological tests and bioassays in highly immunized mothers may not generate any information that proves more useful than ultrasonography and their previous obstetric history.

Mouse/human chimeric antibodies to a tumor-associated antigen: biologic activity of the four human IgG subclasses.

Variable region genes from mouse monoclonal antibody 17-1A (gamma 2a kappa) with specificity for human gastrointestinal malignancies have been paired with human immunoglobulin constant region genes (for heavy and light chains) to produce mouse/human chimeric immunoglobulin molecules (chIgG) for each of the four human IgG subclasses. Mouse 17-1A and the four chIgG bound similarly to two human colon cancer cell lines and had comparable binding affinities. The chIgG1 and chIgG3 molecules mediated lymphocyte and monocyte antibody-dependent cell-mediated cytotoxicity (ADCC) to colon cancer tumor cell lines comparable to that of the parent murine 17-1A. The chIgG2 and chIgG4 molecules were able to mediate ADCC to colon cancer cell lines but were clearly inferior to the chIgG1 and chIgG3 reagents. None of the chIgG antibodies or the murine 17-1A was able to mediate complement lysis of colon cancer cell lines. These studies demonstrate the ability to produce all four human IgG subclass chimeric molecules which retain biologic activity. We have confirmed the subclass preferences of human lymphocyte and monocyte Fc receptors for human IgG subclasses previously determined by studies with monomeric or aggregated IgG. These data may aid in the selection of chimeric antibodies for in vivo trials.

Normalization of monocyte chemotaxis precedes clinical resolution of psoriasis treated with benoxaprofen

Enhanced monocyte activity is present in psoriasis, and benoxaprofen is a drug that inhibits several aspects of monocyte function. To assess a potential pathogenic role of enhanced monocyte function in psoriasis, we determined monocyte chemotaxis and monocyte antibody-dependent cell-mediated cytotoxicity (ADCC) at week 0, 2, 4 and 8 in psoriatics being treated with benoxaprofen. In patients responding to benoxaprofen, normalization of monocyte chemotaxis occurred at week 4, before clinical resolution took place. A significant decrease of monocyte ADCC was also present at week 4, but it was only at week 8, when psoriasis had completely cleared, that monocyte ADCC was completely normalized. In patients receiving placebo or receiving benoxaprofen, but showing no or minimal clinical improvement, monocyte functions remained increased. These results are compatible with the idea that benoxaprofen may improve psoriasis by interfering with monocyte function.

Decreased monocyte antibody-dependent cell-mediated toxicity in stage I-II malignant melanoma. Augmentation by subcutaneous Corynebacterium parvum.

Lymphocyte and monocyte antibody-dependent cell-mediated cytotoxicity (ADCC) against human red blood cells was examined in 28 stage-I-II malignant melanoma patients. Eighteen were studied at various time intervals after receiving SC Corynebacterium parvum (C. parvum); 10 were untreated. Fifteen normal age-matched controls were also studied. Monocyte ADCC was significantly decreased in untreated patients compared with controls (P less than 0.005) and was significantly increased above controls and untreated patients in individuals treated with C. parvum (P less than 0.008). No significant differences in lymphocyte ADCC were seen. Optimal enhancement of monocyte ADCC by C. parvum occurred from 2 weeks to 1 month after treatment. Significant decreases in ADCC to baseline levels occurred in patients studied from 3 to 6 months beyond treatment.

On the Mechanisms of Enhanced Monocyte and Neutrophil Cytotoxicity in Severe Psoriasis

Monocyte and neutrophil function assessed as antibody-dependent cell-mediated cytotoxicity (ADCC) using IgG-sensitizing human erythrocytes as target cells was enhanced in patients with severe psoriasis when compared to healthy controls. We found significant correlation between increased monocyte ADCC and increased neutrophil ADCC, No differences in basal cAMP levels and cAMP responses during initiation of the ADCC reaction was observed between psoriatics and normals. Also degranulation determined as lysozyme release during ADCC was normal. In contrast, the increase in ADCC was significantly correlated to an enhanced hexose monophosphate shunt activation in the effector cells during the cytotoxic reaction. Activity of enzymes responsible for the respiratory burst was not altered in psoriasis since superoxide production after stimulation with phorbol myristate acetate was normal. Likewise, oxygen consumption and degranulation following phagocytosis of opsonized zymosan particles in neutrophils was found normal in psoriasis. Since monocytes showed increased binding of IgG-sensitized erythrocytes these data indicate that the enhanced monocyte and neutrophil ADCC is caused by an enhancement of the respiratory burst possibly induced by increased Fc receptor activity.

Host defense deficiency in hairy cell leukemia and its correction by leukocyte transfusion

A similar defect host defense mechanisms in hairy cell leukemia was defined in two patients. Surface-adherent monocytes were not detected in the peripheral blood nor were monocytes that mediate antibody- dependent cell-mediated cytotoxicity (ADCC) to isoantibody-coated human erythrocytes. In addition, lymphocytes of both patients failed to show blastogenic responses to concanavalin A (Con-A) and pokeweed mitogen (PWM) but showed a vigorous response to phytohemagglutinin (PHA). Other immunologic abnormalities were present but were either moderate in degree or were not present in both patients. In vitro lymphocyte blastogenic responses were fully restored by incubation of patients' leukocytes with a normal donor's adherent monocytes. One patient received daily allogeneic leukocyte transfusion for 4 days. This resulted in complete normalization of monocyte adherence and ADCC that persisted for several months after transfusion and was associated with hemotalogic improvement. Therapy in case 1 resulted in correction of the blastogenic responses to Con-A and PWM. Thus, a host defense defect in hairy cell leukemia has been defined in 2 patients and a preliminary result suggests that therapy with leukocyte transfusions may be useful in the postsplenectomy patient with an infectious complication and should be explored further.

Host Defense Deficiency in Hairy Cell Leukemia and its Correction by Leukocyte Transfusion

A similar defect host defense mechanisms in hairy cell leukemia was defined in two patients. Surface-adherent monocytes were not detected in the peripheral blood nor were monocytes that mediate antibody-dependent cell-mediated cytotoxicity (ADCC) to isoantibody-coated human erythrocytes. In addition, lymphocytes of both patients failed to show blastogenic responses to concanavalin A (Con-A) and pokeweed mitogen (PWM) but showed a vigorous response to phytohemagglutinin (PHA). Other immunologic abnormalities were present but were either moderate in degree or were not present in both patients. In vitro lymphocyte blastogenic responses were fully restored by incubation of patients' leukocytes with a normal donor's adherent monocytes. One patient received daily allogeneic leukocyte transfusion for 4 days. This resulted in complete normalization of monocyte adherence and ADCC that persisted for several months after transfusion and was associated with hemotalogic improvement. Therapy in case 1 resulted in correction of the blastogenic responses to Con-A and PWM. Thus, a host defense defect in hairy cell leukemia has been defined in 2 patients and a preliminary result suggests that therapy with leukocyte transfusions may be useful in the postsplenectomy patient with an infectious complication and should be explored further.

Human Monocyte, Lymphocyte, and Granulocyte Antibody-Dependent Cell-Mediated Cytotoxicity Toward Tumor Cells

Abstract Previous investigations of antibody-dependent cell-mediated cytotoxicity (ADCC) by human leukocytes indicated that lymphocytes and granulocytes, but not monocytes, lysed tumor cell targets. We have recently shown that monocytes, too, can carry out ADCC toward at least three allogeneic tumor cell lines. This paper examines the characteristics of ADCC by all three Fc receptor-bearing human leukocytes (monocytes, lymphocytes, and granulocytes) toward the same antibody-coated 51Cr-labeled tumor target cells. For each leukocyte effector, ADCC was found to be temperature dependent and rapid, with most target cell lysis occurring within 4 hr of incubation. The extent of target cell destruction was positively related to the effector cell/target cell ratio and to the degree of antibody sensitization of the target cells. ADCC was clearly antibody dependent since the cytotoxic event did not involve nonantibody-coated “innocent bystander” target cells and was inhibited by staphylococcal Protein A and nonspecific monomeric immunoglobulin. Granulocyte ADCC required considerably larger amounts of target cell-bound antibody than did ADCC by lymphocytes and monocytes. Conversely, larger amounts of monomeric immunoglobulin were required to inhibit granulocyte ADCC as compared to monocyte and lymphocyte ADCC in experiments utilizing identical antibody-coated target cells. In innocent by-stander experiments, no evidence for a soluble mediator of target cell lysis was found for any of the effector leukocytes. We suggest that this experimental system which involves three Fc receptor-bearing human leukocyte populations and identical antibody-coated target cell preparations provides a new and unique method for studying this cell-mediated cytotoxic event.