Antibody-dependent cellular cytotoxicity (ADCC)-mediated destruction of human immunodeficiency virus (HIV)-coated CD4+ T lymphocytes by acquired immunodeficiency syndrome (AIDS) effector cells

The acquired immunodeficiency syndrome (AIDS) is defined in clinical terms by the development of Kaposi's sarcoma and/or severe opportunistic infections in persons without predisposing conditions. A hallmark of the syndrome has been a decrease in the number of CD4⁺ T helper cells. The reduction in the frequency of the CD4⁺ lymphocytes has been postulated to be primarily the result of human immunodeficiency virus (HIV) tropism and cytophathogenicity for the T-cell subset. Yet only a small percentage of cells is actually infected with HIV. Recently, we provided evidence indicating that AIDS patients' natural killer cells can mediate normal levels of antibody-dependent cellular cytotoxicity (ADCC) despite exhibiting a defect in natural killer (NK) effector function (J Immunol 139:55, 1987). This finding prompted us to investigate whether AIDS patients' effector cells could mediate ADCC against circulating CD4⁺ T cells infected with or expressing HIV antigen. The findings reported herein demonstrate that AIDS effector cells can mediate lysis of CEM (CD4⁺ T-cell line) coated with HIV protein in the presence of HIV-specific antibody. Lysis was specific, as non-HIV-coated CEM or the addition of HIV-negative serum resulted in no lysis. We then examined HIV-coated peripheral blood-derived CD4⁺ T lymphocytes as targets in ADCC. We demonstrate that in the presence of HIV-specific antibody, HIV-coated CD4⁺ T lymphocytes serve as targets for ADCC by AIDS effector cells. The lytic activity obtained with AIDS effector cells was comparable to that obtained with normal effector cells. These results demonstrate that AIDS effector cells can mediate ADCC against HIV-coated CD4⁺ T lymphocytes and suggest that ADCC may play a rolein vivo in the pathogenesis of AIDS.     

Cryopreservation of human mononuclear cells for quality control in clinical immunology. I. Correlations in recovery of K- and NK-cell functions,surface markers,and morphology

Cryopreserved human peripheral blood mononuclear cells (PBMC) were tested for natural killer (NK) and antibody-dependent cellular cytotoxicity (ADCC) and for high-affinity (29°C) and total (4°C) rosette formation with sheep erythrocytes. PBMC produced variable NK activity following freezing and thawing, but consistently reacted well in ADCC. A significant correlation was found between low NK activity and a decreased percentage of low-affinity rosette-forming cells. On the contrary, the number of large granular lymphocytes (LGL), among which NK cells are restricted, and the reactivity with the monoclonal antibody OKT10, which recognizes the majority of LGL in the peripheral blood, were not significantly altered by cryopreservation. Cryopreserved cells proved to be excellent controls for determining the day-to-day variability of the NK assay and for selecting optimum conditions for this test in the clinical immunology laboratory.     

Natural killer (NK) and antibody-dependent cellular cytotoxicity (ADCC) activities can be differentiated by their different sensitivities to interferon and prostaglandin E1

Though purported to be identical cells (or in identical populations of cells), the natural killer (NK) cell mediating spontaneous natural cytotoxicity and the killer (K) cell mediating antibody-dependent cellular cytotoxicity (ADCC) may not be totally identical, at least in susceptibility to regulation by the immunomodulators prostaglandin E₁ (PGE₁) and interferon (IFN). We demonstrate here that NK cells are always enhanced by IFN, while K cells are inhibited from binding targets, resulting in fewer effectors at optimal concentrations of antibody. Only at 10- to 100-fold suboptimal concentrations of antibody is ADCC activity enhanced. As measured by magnitude of inhibition and dose-response titration, ADCC activity is less sensitive to the effects of PGE₁ than is NK activity in the⁵¹Cr release assay and single-cell assay. After overnight incubation with or without PGE₁, whatever sensitivity ADCC activity had to PGE₁ is lost. However, NK cells incubated in the presence of PGE₁ overnight are still sensitive to inhibition. Indomethacin boosts NK activity without having any effect on ADCC activity. Finally, NK activity is substantially reduced by overnight incubation of cells at room temperature, which has no effect on K cells.     

慢性乙肝患者NK,ADCC活性及其对IFN—α,IFN—γ的反应

本文用Hela细胞乳酸脱氢酶释放法测定了42例慢性乙肝病人外周血NK、ADCC活性及其对IFN-α100U/ml、500U/ml及IFN-γ500U/ml预处理4小时后的反应。结果显示,病人PBL NK,ADCC活性与正常对照有显著差别,经IFNs处理后,其NK或/和ADCC活性均有不同程度的升高反应,从而提示了IFNs在慢性肝病治疗中的重要作用。     

A monoclonal antibody (RH1-38) which inhibits multiple systems of cell-mediated cytotoxicity--I. Identification of a novel epitope on a killer cell surface bimolecular complex important in the cytotoxic response

This paper presents the initial characterization of a mouse monoclonal antibody (RH1-38) which blocks, in the absence of complement, three different systems of cell-mediated cytotoxicity. This monoclonal antibody markedly inhibits cytotoxicity mediated by human natural killer cells, a monocyte-like cell [phorbol myristate acetate (PMA) stimulated HL-60], and cytotoxic T-lymphocytes generated in a mixed leukocyte reaction. RH1-38 is not nonspecifically toxic to cells since antibody-dependent cellular cytotoxicity was not inhibited and viability as assessed by trypan blue exclusion was not affected. Inhibition is specific since control hybridoma culture supernatants, parent (NS-1) ascites supernatant, monoclonal anti-HLA and normal mouse IgG were not significantly inhibitory. In the NK system, the inhibitory effect appears to be due to binding of monoclonal antibody to effector cell surface since exposure of targets to antibody followed by washing yielded no inhibition of killing. Inhibition requires the antigen-binding portion of the antibody molecule and thus appears to be related to steric hindrance of an effector cell surface molecule which is important in the expression of cell-mediated cytotoxicity. Immunoprecipitation of surface-radioiodinated membranes from PMA-stimulated HL-60 cells and analysis on sodium dodecyl sulfate-polyacrylamide gels revealed a bimolecular complex (195,000 and 125,000 daltons) without significant change under reducing conditions. Control immunoprecipitates yielded no peaks of activity. This monoclonal antibody should serve as a useful probe of the function and biochemistry of a killer cell surface antigen important in the expression of cell-mediated cytotoxicity. Since RH1-38 inhibits cytotoxicity mediated by at least three apparently unrelated effector cells, the relevant antigen may be part of a common mechanistic step. As the companion paper demonstrates, this monoclonal antibody does not affect the conjugation step, but appears to block a late step in the NK cytolytic mechanism. Thus, RH1-38 recognizes either an epitope district from previously-described anti-LFA-1 antibodies or alternatively recognizes a distinct functional killer cell surface molecule.     

Vaccine-Induced Protection from Homologous Tier 2 SHIV Challenge in Nonhuman Primates Depends on Serum-Neutralizing Antibody Titers

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Association between HLA and Japanese patients with rheumatoid arthritis

Japanese patients with rheumatoid arthritis (RA) were observed to have a statistical association with HLA-DR4, MT3. Strong association between the clinical severity of RA and HLA was also observed. Male patients had a stronger association with HLA than female patients. Males are more resistant to RA than females. This suggested that the threshold of liability for RA is higher in males than in females. Japanese patients with RA with systemic vasculitis were negative for HLA-Bw44 and had antilymphocytotoxic autoantibody, indicating that RA with systemic vasculitis is different in etiology from RA without systemic vasculitis.     

工频电磁场对人体免疫功能的作用

目的　探讨工频电磁场对人体免疫功能的影响。方法　检测２５ 例长期工作在３ ×１０５ Ｖ超高压环境中的工作人员与５ 例正常对照者的外周血Ｔ 淋巴细胞分泌白细胞介素２（ＩＬ２） 活性,白细胞介素２ 受体（ＩＬ２Ｒ） 表达;单核／ 巨噬细胞抗体依赖的细胞介导的细胞毒（ＡＤＣＣ） 效应,白细胞介素１５（ＩＬ１５） 活性;血清中ＩｇＧ、ＩｇＡ、ＩｇＭ 的水平。结果　（１） 观察组ＩＬ２ 活性为（３６２ ±７８） Ｕ／ｍｌ,明显高于对照组［（２５４ ±６７）Ｕ／ｍｌ］ ,差异有显著性（ Ｐ ＜ ０ ．０５） 。（２） 观察组ＩＬ２Ｒ 表达比率为２８ ．４ ％ ±３ ．２ ％ ,对照组为２２ ．８ ％ ±１０ ．７ ％ ,差异无显著性（ Ｐ ＞ ０ ．０５） 。（３） 观察组单核／ 巨噬细胞ＡＤＣＣ 效应及ＩＬ１５ 分泌水平均有增强或增高的趋势,但差异无显著性（ Ｐ ＞ ０ ．０５） 。（４） 观察组血清中ＩｇＧ 水平为（１０ ．３７ ±１ ．２８）ｇ／Ｌ,明显高于对照组［（８ ．８９ ±１ ．８８）ｇ／Ｌ］ ,差异有显著性（ Ｐ ＜ ０ ．０５） ,而血清中ＩｇＡ、Ｉｇ Ｍ 水平与对照组比较,差异无显著性（ Ｐ ＞ ０ ．０５） 。结论　长期工作在工频电磁场环境中人员的Ｔ     

A high affinity recombinant antibody to the human EphA3 receptor with enhanced ADCC activity

Abstract

EphA3is expressed in solid tumors and leukemias and is an attractive target for the therapy. We have generated a panel of Humaneered® antibodies to the ligand-binding domain using a Fab epitope-focused library that has the same specificity as monoclonal antibody mIIIA4. A high-affinity antibody was selected that competes with the mIIIA4 antibody for binding to EphA3 and has an improved affinity of ～1?nM. In order to generate an antibody with potent cell-killing activity the variable regions were assembled with human IgG1k constant regions and expressed in a Chinese hamster ovary (CHO) cell line deficient in fucosyl transferase. Non-fucosylated antibodies have been reported to have enhanced binding affinity for the IgG receptor CD16a (FcγRIIIa). The affinity of the antibody for recombinant CD16a was enhanced approximately 10-fold. This resulted in enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) activity against EphA3-expressing leukemic cells, providing a potent antibody for the evaluation as a therapeutic agent.