Human lymphocyte dependent antibody mediated cytotoxicity: adherence of lymphocytes to antibody treated target cells

Antibody-dependent cell-mediated cytotoxicity (ADCC) of penicillin-treated human red blood cells

Penicillin-treated human red blood cells (RBC) were lysed by the cooperation of autologous nonsensitized peripheral blood mononuclear cells and human anti-penicillin serum. Using a rapid (3 h) assay of antibody-dependent cell-mediated cytotoxicity (ADCC), lysis was proportional to serum (anti-penicillin antibody) concentration, to incubation time and to the concentration of attacking cells, which were obtained from normal human peripheral blood by Ficoll-Hypaque separation. Incubation of these lymphoid effector cells on a nylon column prior to the tests depleted the number of phagocytic (latex positive) cells in the effluent; there was a concomitant drop in cytotoxic activity. Enrichment of mononuclear phagocytes in the attacking cell population by albumin gradient separation led to an increase in cytotoxicity. Granulocytes separated by Ficoll-Hypaque were not active in this system. Using specific antisera the antibody was found to be of the IgG1 sub-class. Anti-penicillin antibody activated the complement system in vitro, but failed to induce lysis of penicillin-treated RBC in the presence of complement without attacking cells. These results suggest that ADCC may participate in the destruction of RBC in penicillin-induced haemolysis in vivo.

ADCC effector function in patients with atopic dermatitis. A possible mechanism of susceptibility to severe cutaneous viral infections

Peripheral blood mononuclear cells from patients with chronic atopic dermatitis were evaluated as effectors of antibody-dependent cellular cytotoxicity (ADCC) to determine if faulty effector function might explain the susceptibility of atopics to severe cutaneous viral infections in spite of adequate specific antibody titers. Eleven atopic patients whose dermatitis was well controlled and who were not infected or on immunosuppressive therapy were studied using sensitized human and chicken erythrocyte targets at three different effector:target ratios. No significant differences in mean ADCC were seen between atopics and controls. However, the function of peripheral blood mononuclear cells from atopic patients who had a previous history of severe cutaneous viral infection was significantly depressed against sensitized chicken, but not human targets. This suggests that atopic patients who develop severe cutaneous viral infections may represent a subset of atopics with an intrinsic or variable defect in K lymphocyte--mediated ADCC which might render them susceptible to persistent, extensive viral infections.

Antibody-dependent, cell-mediated cytotoxicity against human red blood cells: correlation of effector cell type with enzymatic alteration of the target cell surface

Target cell factors, which contribute to the determination of the effector cell type in an antibody-dependent, cell-mediated cytotoxicity system were studied. Human red blood cells (RBC) were treated with papain and investigated by transmission and scanning electron microscopy (TEM and SEM). Both untreated (native) and treated 0 Rh+ RBC were labeled with 51Cr, sensitized with anti-D immunoglobulin and incubated with unfractionated autologous peripheral blood mononuclear cells. With native RBC, immune lysis was proportional to the number of phagocytes: enrichment of effectors in phagocytes increased lysis, while depletion of phagocytes from effectors decreased lysis. Following papain treatment of target RBC, lysis by unfractionated mononuclear effectors was markedly augmented; since this effect was not diminished by decrease of phagocytes to less than 2%, the augmented lysis was not due to the number of phagocytic effectors. TEM and SEM of enzyme-treated RBC showed spherocytosis with varying degrees of crenation and blurring and irregularities of the cellular membranes. The results suggest that papain-induced alterations in the target RBC rendered them susceptible to lysis by interaction between anti-D antibody and peripheral blood lymphocytes.