Antibody-dependent cell-mediated cytotoxicity in selected autoimmune diseases

Cytotoxic responses to alloantigens in systemic lupus erythematosus

We have studied the ability of the peripheral mononuclear cells (MNC) from patients with systemic lupus erythematosus (SLE) to generate a cytotoxic (CML) response against alloantigens. CML responses in SLE patients were significantly lower than those of normal individuals. Mixed lymphocyte reaction (MLR) assays conducted in parallel in these patients were decreased but to a lesser extent. Some of the patients exhibited parallel decreases in both CML and MLR tests, while others showed decreased CML responses but normal MLR responses. Optimal CML responses in SLE patients did not occur at a different time point than in the normals. Plasma from most SLE patients tested did not have an effect on CML and MLR responses of normal MNC; the plasma of only one patient consistently decreased the CML of normal cells. Depletion of adherent cells from MNC of SLE patients by Sephadex G-10 fractionation allowed better CML and MLR responses. Low CML responses in patients with SLE were associated with increased disease activity and increased serum DNA binding. No association between MLR responses in SLE patients and any of the above parameters was detected. SLE patients not having received any cytotoxic treatment exhibited the lowest CML responses, while these under treatment or treated in the past had higher, although not normal, responses. MLR responses were not affected by the treatment status of the patients.

Antibody-dependent cytotoxicity mediated by cells eluted from synovial tissues of patients with rheumatoid arthritis and juvenile rheumatoid arthritis

Cell suspensions containing an average of 78% lymphocytes were obtained from synovial tissues of 26 patients with rheumatoid arthritis and 10 patients with juvenile rheumatoid arthritis. These cells were shown to mediate cytotoxicity against 51Cr-labeled chicken erythrocytes sensitized with a rabbit anti-chicken erythrocyte antiserum. Nylon column filtration of the cells increased the proportion of lymphocytes and usually also the cytotoxicity, which suggested that at least some of the effector cells were lymphocytes. The cytotoxic activity of the cells obtained from rheumatoid synovial tissue was always lower than that obtained with the patients' peripheral blood lymphocytes. No significant change in cytotoxicity of normal peripheral blood lymphocytes was observed after these cells had been treated in the same manner as the rheumatoid synovial tissues.

Deficient interleukin-2-activated killer cell cytotoxicity in patients with systemic lupus erythematosus

This study was undertaken to determine if the cytotoxic activity of interleukin-2 (IL-2)-activated killer (LAK) cells, which is induced by the direct activation of lymphocytes by IL-2, is defective in systemic lupus erythematosus (SLE). The killer cell activity of SLE patients, whether it be generated in autologous plasma or serum-free media, was significantly less than the controls against three different target cells. It was observed, by incubating control lymphocytes in 10% fresh SLE plasma, that soluble factors were responsible for a portion of the reduced generation of LAK cell cytotoxicity (P less than 0.05). Suppression ranges from 4 to 70% with a mean of 33%. However, when SLE LAK cells were generated in serum-free media, a greater reduction of generated LAK cell activity was observed (P less than 0.005). Using a disease activity score, it was determined that SLE cytotoxicity negatively correlated with disease activity only when the cells were cultured in serum-free media. Irrespective of the culture conditions, lytic activity did not correlate with levels of anti-DNA antibodies, anti-Sm antibodies, circulating immune complexes, or prednisone therapy.

Studies on human blood lymphocytes with iC3b (type 3) complement receptors: III. Abnormalities in patients with active systemic lupus erythematosus

Lymphocytes displaying iC3b (Type 3) complement receptors (CR3) were quantified by flow cytometry in patients with systemic lupus erythematosus. The percentages and absolute numbers were compared to age and sex matched controls. Total CR3+ lymphocytes identified by the monoclonal antibodies OKM1 or Leu 15 were significantly decreased in patients with symptomatic arthritis, serositis or vasculitis and those with lupus nephritis, whereas values for CR3+ lymphocytes in patients with inactive disease were similar to normal donors. The phenotype of CR3+ lymphocytes was markedly different in patients with active SLE. In normals granular lymphocytes bearing Fc receptors for IgG (L cells) comprised two-thirds of CR3+ lymphocytes. However, in SLE this subset was reduced to 20% and there was a corresponding increase in CR3+ lymphocytes co-expressing the T3 marker. Percentages of CR3 T4+ but not CR3+ T8+ lymphocytes were significantly increased in SLE. Although patients with active disease were lymphopenic, absolute numbers of CR3+ lymphocytes co-expressing T cell markers were similar to normal controls. Since L cells are non-specific suppressors of Ig production, the reduction of this subset along with the increase in CR3 T4+ cells could contribute to unregulated antibody production characteristic of SLE.

The role of immunotherapy in type I diabetes mellitus

Type I diabetes mellitus appears to result from an insidious immunologic destruction of pancreatic beta-cells in genetically susceptible persons exposed to one or a series of environmental insults. This genetic susceptibility is related to alleles located on the sixth chromosome in the HLA-DR or an adjacent region. With superimposition of a viral or other environmental triggering event, cell-and antibody-mediated events are activated that lead to the specific autorejection of beta-cells and consequent insulin deficiency. Immunosuppressive strategies to impede or halt complete destruction of beta-cells, using cyclosporine, have already been initiated in both animals and humans with diabetes mellitus. Because of the potential toxicity of all current immunosuppressive regimens, such therapies cannot, at this time, be considered for wide-scale use in persons with type I diabetes. Reported inductions, however, of insulin independence in patients with newly diagnosed type I diabetes using cyclosporine or other agents underscore the role of the immune system in the pathogenesis of the disease and highlight the need to develop safer, more specific immunomodulation designed to avoid complete beta-cell destruction.

Deficient gamma-interferon production in patients with systemic lupus erythematosus

We examined the ability of peripheral mononuclear cells (MNC) from patients with systemic lupus erythematosus (SLE) to produce gamma-interferon (gamma-IFN) in vitro. MNC from patients with SLE produced varying amounts of gamma-IFN upon mitogenic stimulation. However, they produced distinctly decreased amounts of gamma-IFN upon in vitro stimulation with interleukin-2 (IL-2). Deficient production seemed to be primary, rather than secondary to either excessive monocytic suppression or failure of IL-2 to bind to the MNC surface membranes. gamma-IFN-specific RNA transcription, as determined by slot-blot analysis, was severely decreased in MNC that had been stimulated with phytohemagglutinin or IL-2. These findings suggest that MNC of patients with SLE have defects in the IL-2 signal transduction which is required for production of gamma-IFN.

Interleukin-2 restores the depressed allogeneic cell-mediated lympholysis and natural killer cell activity in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is characterized by a variety of profound T-cell abnormalities among which are decreased cytotoxic capacity measured by allogeneic cell-mediated lympholysis (CML), natural killer cell (NK) activity, and decreased lymphokine production. In a group of 13 patients with active SLE, allogeneic CML, tested by a 4-hr 51Cr-release assay, was 18.2 +/- 2.7% while in the group of normal individuals CML was 41.2 +/- 2.7%. If optimal doses of affinity-purified interleukin-2 (IL-2) were present during the mixed lymphocyte culture, the CML of SLE patients was increased to normal levels (40.4 +/- 4.0%). In contrast, interferon-alpha (IFN-alpha) increased (but not significantly) the levels of CML. Mixed lymphocyte reaction, tested by tritiated thymidine incorporation, was also decreased in the group of patients (14,820 +/- 815 cpm vs 28,972 +/- 5880 cpm in normals) and it was increased to normal levels if IL-2, but not IFN-alpha was added to the cultures. NK activity was decreased in the group of patients tested by 51Cr-release assay, harvested at 6 and 18 hr. IL-2 increased the NK activity up to normal levels, while IFN-alpha was only partially efficacious. These results demonstrate that IL-2, but not IFN-alpha, can potentiate or even fully restore the deficient cytotoxic effector function of peripheral mononuclear cells in patients with SLE.

Primary Sjogren syndrome: clinical and immunopathologic features

Primary Sjogren syndrome is an autoimmune condition in which dry eyes (keratoconjunctivitis sicca) and dry mouth (xerostomia) result from lymphocytic infiltration of lacrimal and salivary glands. Clinical and laboratory features of 60 primary Sjogren syndrome patients seen at our clinic during the past three years are presented. These patients illustrate the wide spectrum of extraglandular features that may occur as a result of lymphoid infiltration of lung, kidney, skin, stomach, liver, and muscle. They further emphasize the difficulty in classifying a patient as primary or secondary Sjogren syndrome (ie, sicca symptoms associated with systemic lupus erythematosus, rheumatoid arthritis, or scleroderma), particularly early in the disease course. As an initial step in understanding the pathogenesis, the lymphocytes that infiltrate the salivary glands and lymph nodes were characterized by using monoclonal antibodies that recognize distinct lymphocyte subsets and by using in vitro functional assays. These studies have demonstrated that affected tissues have infiltrates of T cells with helper/inducer activity and with a high frequency of "activation antigens." The immunohistologic techniques are useful in differentiating "benign" and "pseudolymphoma" lesions (both due predominantly to T cells) from non-Hodgkin lymphoma (usually due to B-cell infiltrates). Although there is no "cure" for primary Sjogren syndrome patient's symptoms may be significantly improved by measures aimed at prevention of ocular and dental complications and by the recognition of extraglandular features that may be amenable to specific treatment.

Natural cytotoxicity in systemic lupus erythematosus: mechanisms of suppression by inhibitory serum factors

Spontaneous cytotoxicity mediated by natural killer (NK) cells is impaired in several human diseases including systemic lupus erythematosus (SLE). The present study was designed to describe factors in SLE sera which suppress the NK function of unfractionated mononuclear cells and NK enriched suspensions. NK activity was determined in 19 SLE patients and 25 normal controls by a standard chromium release assay. Sera obtained from SLE patients suppressed normal NK activity by an average of 29.4%. The presence of anti-lymphocyte antibodies (ALA) of the IgM class which were reactive with unfractionated mononuclear cells or the NK cell enriched OKM1 positive subset correlated with serum-mediated suppression. NK inhibitory SLE sera did not interfere with normal effector-target conjugate formation. These results demonstrate the modulatory effects of immune aggregates and ALA on lymphocyte function in SLE. These factors suppress NK function without evidence of lymphocyte cell death or inhibition of NK effector cell binding to tumour targets.

Antibody-dependent cellular cytotoxicity in chronic human Chagas disease

Antibody-dependent cellular cytotoxicity mediated by granulocytes (ADGC) or lymphocytes (ADLC) was assessed in 23 patients with chronic Chagas disease. The results of ADGC against T. cruzi were normal. ADLC against chicken erythrocytes was significantly reduced in patients as compared with normal controls. Possible causes of this abnormality were investigated.

K-cell activity in aplastic anaemia

K-cell activity was measured by specific cytotoxicity and cytotoxic capacity in 29 patients with aplastic anaemia. 9 patients had a reduction of the specific cytotoxicity and 12 had a decreased cytotoxic capacity. The decreased cytotoxic capacity correlates with the severity of aplastic anaemia. Some of the possible causes of the reduction of this activity were investigated.

Peripheral K cells in Graves' disease and Hashimoto's thyroiditis in relation to circulating immune complexes

A plaque assay was employed to quantify the number of peripheral K cells in autoimmune thyroid diseases. The percentages of peripheral K cells determined were 3.1 +/- 2.2% and 3.3 +/- 1.3% (mean +/- SD) in forty-one patients with Graves' disease and twenty-two patients with Hashimoto's thyroiditis, respectively, which were significantly lower than 5.3 +/- 2.5% in 22 normal subjects. Circulating immune complexes (ICs) were measured by three different methods. The positivity of these ICs was investigated in relation to the level of peripheral K cells. The percentage of peripheral K cells in the patients positive for ICs was found to be lower than that in the patients negative for any ICs. Moreover, it was observed that the number of detectable K cells from a normal subject was significantly decreased by incubating the K cells with sera of patients positive for ICs. These results suggest that the decrease of peripheral K cells in the patients with autoimmune thyroid diseases may be due to saturation of K cell Fc receptors by binding ICs.

Phenotypes of T lymphocytes in systemic lupus erythematosus: decreased cytotoxic/suppressor subpopulation is associated with deficient allogeneic cytotoxic responses rather than with concanavalin A-induced suppressor cells

Patients with systemic lupus erythematosus (SLE) have decreased precursors of cytotoxic/suppressor T lymphocytes in their peripheral blood, as determined by monoclonal antibodies. To determine whether decrease of the cytotoxic or the suppressor parts (or both) of this subpopulation of T lymphocytes is being reflected by this peripheral mononuclear cell (MNC) abnormality, a series of experiments was conducted in which both the suppressive function (concanavalin A induced and spontaneous) and the generation of cytotoxic responses against alloantigens were tested. Cytotoxic responses were consistently diminished while suppressor capacity of MNC from patients with SLE (measured on several assays of normal T- and B-lymphocyte functions) was comparable to that of MNC from normal individuals. The defect in cytotoxic responses to alloantigens by MNC from SLE patients persisted following secondary stimulation in mixed-leukocyte cultures; the cytotoxic responses were not amplified and remained well below the responses of normal MNC. These experiments indicate that the decreased peripheral population of cytotoxic/suppressor lymphocytes in SLE patients represents low or absent precursors of cytotoxic cells rather than of precursors of suppressor cells.

Natural cytotoxicity of peripheral blood leukocytes from normal subjects and patients with Hashimoto's thyroiditis against human adult and fetal thyroid cells

Natural cytotoxicity of human peripheral blood leukocytes against fetal and adult human thyroid cells was investigated in vitro. Natural killer (NK) cell activity was determined at various effector: target cell ratios in a standard 51Cr release assay with human thyroid cells as targets. The effector cells were unfractionated peripheral blood mononuclear cells obtained by Hypaque-Ficoll gradient centrifugation. We have demonstrated that peripheral blood leukocytes from normal subjects and patients with Hashimoto's thyroiditis exhibit natural cytotoxicity against both human fetal and adult thyroid cells. This was effector: target cell ratio and incubation time dependent. Although there was a tendency for increased killing of fetal thyroid cells by peripheral blood leukocytes from patients with Hashimoto's thyroiditis compared to age/sex matched normal subjects this was not significant and there were no significant differences between the two groups for killing of adult thyroid cells. A possible role for natural cytotoxicity in progressive thyroid tissue destruction in Hashimoto's thyroiditis is discussed.

Heterogeneity of antilymphocyte antibody in SLE and its correlation with disease activity

The cytotoxic activities of individual lupus sera were demonstrated against T gamma cells, T gamma (-) cells and B cells. Immunoglobulin classes were also determined in these antilymphocyte antibodies (ALA) in SLE. T gamma-specific ALA and B-cell-specific ALA were almost equally distributed as regards IgG-dominant type, mixed IgG and IgM type and IgM dominant type, while IgM dominant type was predominant in T gamma (-)-specific ALA. Only the IgG type of T gamma-specific ALA among these ALA was significantly associated with clinical parameters, including hypocomplementemia, elevated immune complex levels and high anti-double-stranded (ds) DNA titres. Serial studies on ALA in a typical case of SLE were performed. Active clinical signs were associated with elevated cytotoxicities of IgG type of T gamma-specific ALA and with relatively low cytotoxicities of the IgM type, whereas after massive corticosteroid therapy, these signs disappeared in tact with the reduction in cytotoxic activities of IgG type of the ALA and the relative rise in cytotoxicities of IgM type of the ALA. These results suggested that IgG class of T gamma-specific ALA seemed to play a major role among several types of ALA in SLE.

Natural killer cells and interferon responses in patients with systemic lupus erythematosus

Natural killer (NK) cell activity was studied in 23 patients with systemic lupus erythematosus (SLE). The overall NK activity was lower in patients with SLE than in normal female individuals. Patients with clinically active SLE disease had slightly lower NK activity than the patients with inactive disease. Other clinical parameters as well as treatment status did not correlate with NK activity. Interferon (IFN) enhanced the NK activity of normal individuals and of 11 SLE patients, while it did not enhance in the remaining 12 patients. The patients whose NK activity was enhanced by beta-IFN had significantly higher initial activity than those who did not respond to beta-IFN. Furthermore, peripheral mononuclear cells (MNC) from IFN responders produced gamma-IFN after stimulation with concanavalin A (Con A) in titres comparable to those of normals. In contrast, peripheral MNC from beta-IFN non-responders failed to produce significant titres of gamma-IFN after stimulation with Con A. These results indicate that certain patients with SLE have low NK activity, which is generally paralleled by an inability to respond to exogenous beta-IFN and by blunted production of gamma-IFN after stimulation with Con A.

Immunological studies in patients with rheumatoid arthritis receiving azathioprine and myocrisin in combination

Thirty-one patients with classical or definite rheumatoid arthritis (RA), on treatment with azathioprine and sodium aurothiomalate in combination were studied. Absolute lymphocyte counts and IgA levels were reduced but this did not reach statistical significance. Lymphocyte transformation with phytohaemagglutinin (PHA) showed no significant difference from a control group. However, antibody dependent cell-mediated cytotoxicity was significantly impaired compared to rheumatoid controls (p less than 0.001). There was no relation to the degree of impairment of ADCC and the current dose of azathioprine nor to the total dose or duration of therapy. Inhibiting material to cell-mediated cytotoxicity was present in the sera of 23 patients but its presence showed no relation to the degree of cytotoxicity exhibited by cells in the same patient. Our studies of cellular cytotoxicity have revealed alterations in cellular function possibly attributable to azathioprine.

Measles virus panniculitis subsequent to vaccine administration

A severe illness developed gradually in a healthy boy following administration of live measles vaccine at age 14 years. Killed measles vaccine had been given at age 2. Panniculitis began near the site of live vaccine injection, extended contiguously to involve the entire upper arm, and then began to appear in distant subcutaneous sites. He was febrile, leukopenic, anemic, and lost weight rapidly. Evidence of a cause-and-effect relationship between the lesions and the measles vaccine included biopsy findings of particles closely resembling measles nucleocapsids and complete virions by electron microscopy, positive fluorescence after staining with two anti-measles nucleocapsid sera, and immunologic aberrations. The lesions regressed after various treatments and completely remitted on two occasions, but recurred. He became severely malnourished and finally died 29 months after the measles vaccination. At autopsy, pannicultitis was found in the subcutis and mesentery, without evidence of involvement of the brain or other vital organs.

Antibody-dependent cellular cytotoxicity against drug-induced antigens in L5178Y mouse lymphoma

In vivo treatment with antineoplastic compounds has been reported to lead to the expression of new antigenic specificities which were not detected on parental cells, and which were transmissible as a genetic character. The current study is concerned with antibody-dependent cellular cytotoxic (ADCC) activity in serum of syngeneic mice challenged with LY/DTIC cells, a subline of LY murine lymphoma, antigenically altered by the drug DTIC. LY/DTIC target cells coated with LY/DTIC-immune serum were specifically lysed by virgin lymphocytes. The genetic background of the effector cells, whether syngeneic, allogeneic or xenogeneic, did not produce significant differences in the percentage of target-cell lysis. ADCC activity was reduced when the immune serum was added directly to the incubation medium, without precoating. Although sera from individual animals exhibited different levels of ADCC activity, they nevertheless followed the general trend of the pooled sera. Peak activity of ADCC was obtained in the sera collected on Days 8 and 30 after LY/DTIC cell challenge. The ADCC activity elicited by LY/DTIC cells may contribute to the rejection of drug-altered tumour cells.

T lymphocyte interaction with immunoglobulin G antibody in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease with multiple immune disturbances whose mechanisms remain unclear. We examined the interaction of antilymphocyte antibodies with cultured normal T lymphocytes. T cells were prepared by E-rosetting after petri-dish removal of adherent cells and cultured for 2-7 d in the presence of SLE sera or normal human sera. Cultured T cells were washed and sonicated, and the amount of cell-associated IgG was quantitated by radioimmunoassay or enzyme-linked immunoassay (ELISA) methods. T cells cultured with 27 of 39 SLE sera showed marked increments of associated immunoglobulin G (IgG) although this was not observed with sera from mixed connective tissue disease patients containing high titers of ribonucleoprotein antibody or normal donors. The effective factors for IgG association in SLE sera were absorbed with normal peripheral blood lymphocytes or T cells. Anti-T cell IgG cytotoxic activity strongly correlated with T cell IgG association (P less than 0.01). T cell-associated IgG was not removed by stripping of cell membrane IgG from living cells by acid buffer treatment; indirect immunofluorescence of cells fixed after 2-4 d of culture revealed cytoplasmic IgG staining. IgG anti-T cell antibodies appeared to associate inside the cell membrane or to penetrate into the cytoplasm of cells. T cell Fc receptor blocking by heat-aggregated IgG or anti-beta 2-microglobulin antibody did not alter IgG cell association. Since pepsin-digested SLE sera showed no T cell association activity, whole IgG antibody molecules appeared to be necessary for interaction with cultured T cells. In addition, reduction and alkylation of active SLE sera completely nullified T cell reactivity. When normal T cells were cultured with SLE sera showing marked IgG T cell association, viability of cultured T cells decreased rapidly after 4 d, which suggests that IgG anti-T cell antibodies were associated with cell destruction. IgG cell-associating antilymphocyte antibodies present in SLE sera may cause T cell disturbances in vivo and may be related to the lymphocytopenia present in SLE patients.

Depressed natural and lectin-dependent cell-mediated cytotoxicity against adherent HEp-2 cells in patients with systemic lupus erythematosus

Natural cell-mediated cytotoxicity /NCMC/ was evaluated using human adherent 3H-thymidine-prelabelled HEp-2 epipharynx carcinoma cells as targets at 50:1 effector-target cell ratio in a 24 hr assay. For lectin-dependent cell-mediated cytotoxicity /LDCC/ studies cultures contained also 25/micrograms/ml concanavalin A /Con A/. Peripheral blood mononuclear cells /PBMC/ of nine patients with active systemic lupus erythematosus /SLE/ failed to exert NCMC or LDCC against HEp-2 targets. In contrast, an increased adherence /decreased detachment from the monolayer/ of HEp-2 target cells was observed in the presence of PBMC from SLE patients that was further promoted by the addition of Con A during LDCC assay.

Defective monocyte cytotoxicity in rheumatoid arthritis: a correlation with disease activity and reversal by levamisole

The cytotoxic activities of human blood mononuclear cells against certain established cell lines were evaluated prospectively in 17 patients with rheumatoid arthritis before and after treatment with low (150 mg per week) and moderate doses (300 mg per week) of levamisole. Spontaneous or "natural" killer activity (NK) and antibody-dependent cellular cytotoxicity (ADCC) of plastic adherent cells ("monocytes") and lymphocytes were studied. We report a selective cytotoxic defect in monocyte NK and a correlation of this defect with severely active disease. The patients with the most severe defect responded to low-dose levamisole, but others with normal values did nor respond as well to treatment. This cytotoxic defect may be an important pathogenetic factor in rheumatoid arthritis and this new assay may be helpful in selecting candidates who are most likely to respond to levamisole.

Antibody-dependent cellular cytotoxicity in recurrent aphthous ulceration

Antibody-dependent cellular cytotoxicity (ADCC) was investigated as s possible mechanism of pathogenesis in recurrent aphthous ulceration (RAU). ADCC induced by mononuclear cells from patients at various stages of RAU was compared with ADCC induced by mononuclear cells from paired controls. Chicken red blood cells (ChRBC) coated with rabbit anti-ChRBC antibody were used as targets. A significant increase in ADCC (P less than 0.01, paired sample t-test) in patients' samples as compared with controls was found only at the early stage of the disease. No increased cytotoxicity over control values was observed at any other single stage of the disease. The transient increased cytotoxicity observed in the early stage of RAU may reflect a number of possible mechanisms, including an increased number of ADCC effector cells only at the early stage, an increase in Fc receptor avidity, or an increase in efficiency of the existing effector cell population.

Antibodies to T cells in patients with systemic lupus erythematosus can induce antibody-dependent cell-mediated cytotoxicity against human T cells

Patients with active systemic lupus erythematosus (SLE) often have circulating antibodies to T cells. These patients also often have leukopenia and diminished numbers of T lymphocytes. In addition, certain T lymphocyte functions are frequently impaired in patients with SLE. It has been previously considered that a complement-dependent cytotoxic mechanism was responsible for the above observations. We now demonstrate that antibody-dependent cell-mediated cytotoxicity (ADCC), a cytotoxic reaction mediated by antibody and effector cells in the absence of complement, can also kill T cells from normal individuals as well as from patients with SLE. Moreover, this ADCC could be observed using the plasma, effector cells, and target cells all obtained from the same individual with SLE. Plasma of those patients with active SLE, and in whom anti-T cell antibodies could be demonstrated by the more classical complement-dependent cytotoxicity, was most often able to mediate such an ADCC reaction. The IgG fraction of the plasma was responsible for inducing ADCC, and aggregated IgG could block the reaction. The fact that the IgG fraction was often more effective than the unfractionated plasma suggested that immune complexes present in SLE plasma might partially block the expression of ADCC. Because a single SLE plasma could induce ADCC in T cells from several different unrelated individuals, it is unlikely that antibodies directed against particular human leukocyte antigens (HLA) or blood group antigens are involved.

Raji cell assay for immune complexes. Evidence for detection of Raji-directed immunoglobulin G antibody in sera from patients with systemic lupus erythematosus

We asked whether binding of human immunoglobulin (Ig)G antibody reacting with Raji cells could be distinguished from binding of IgG immune complexes. Using a standard Raji assay employing 125I-IgG goat anti-human Fc gamma, we found that digestion of Raji cells with pronase reduced by 95% their ability to bind complement-fixed aggregated human gamma globulin and complement-fixed tetanus toxoid-antitetanus toxin complexes. However, binding at 37 degrees C of IgG from the sera of 16 patients with systemic lupus erythematosus (SLE) to pronase-digested Raji cells was reduced much less consistently and extensively (9-100% reduction; mean reduction of 51%). In more detailed studies of two SLE sera, sucrose density gradient centrifugation showed that greater than 50% of the IgG binding to undigested Raji cells sedimented in the 7S region. Pepsin digestion of immunoglobulin fractions from four SLE sera caused a reduction in SLE IgG binding to undigested Raji cells when detected with 125I anti-Fc gamma, but an increase when binding was detected with 125I-anti-Fab, suggesting that substantial SLE IgG can bind through F(ab')2 regions. Binding of IgG from SLE sera was not directed at neoantigenic sites induced by pronase digestion because binding activity was adsorbed with undigested cells as readily as with digested cells. Moreover, sera from 10 SLE patients that had negative Raji assays contained no IgG that bound to pronase-digested Raji cells. We conclude that much of the IgG bound at 37 degrees C to Raji cells from the sera of many patients with SLE does not represent immune complexes but is probably antibody directed toward sites on the Raji cell.

Immunoregulation in Sjögren's syndrome: influence of serum factors on T-cell subpopulations

21 patients with Sjögren's syndrome (sicca syndrome) with either glandular or extraglandular involvement, but without other connective tissue diseases, were studied with regard to immunoregulatory T-cell subpopulations, B-cell function, and suppressor cell capabilities. Patients with isolated glandular disease as well as patients with extraglandular disease had normal absolute numbers of total lymphocytes, T cells, and B cells. However, 9 of 11 patients with extraglandular disease and only 3 of 10 patients with glandular disease had decreased relative proportions of T cells bearing receptors for the Fc portion of immunoglobulin (Ig)G (T(G)) which was explained by a factor that blocked the expression of the IgG Fc receptor on T(G) cells. This blockage was reversible since the factor could be removed by trypsinizing the T cells before T(G) determination. Serum from patients with abnormal proportions of T(G) cells, but not serum from patients with normal proportions of T(G) cells, blocked the expression of the IgG Fc receptor on normal T cells. The serum factor upon fractionation over Bio-Gel A 1.5 columns as well as over staphylococcal protein A-Sepharose 4B columns was found diffusely within the IgG fraction, and not in the IgM fraction. Neither patients with glandular nor patients with extraglandular disease manifested increased numbers of in vivo-activated circulating lymphocytes as determined by spontaneous anti-trinitrophenyl (TNP) plaque-forming cells (PFC). However, patients with glandular disease had reduced numbers of pokeweed mitogen-induced anti-sheep erythrocyte PFC (P < 0.01) as compared with normals and patients with glandular disease. Of note was the fact that despite the modulation of T(G) subpopulation by the serum factor in patients with extra-glandular disease, these patients manifested normal concanavalin A-generated suppressor cells of pokeweed mitogen-induced PFC responses in allogeneic co-cultures. This was unlike the suppressor cell defect previously described in this system with systemic lupus erythematosus patients. The discrepancy was attributed both to the fact that the T(G) defect was reversible and to the fact that concanavalin A-generated suppressor cells are not limited to the T(G) subset. Thus, these studies have demonstrated reversible abnormalities in T(G) cells in patients with extraglandular Sjögren's syndrome which are not associated with suppressor cell defects. The discrepancy between these findings and the immuno-regulatory defects demonstrated in systemic lupus erythematosus may explain the difference in severity of the autoimmune expression in these diseases.

Antibody-dependent killer-cell function in insulin-dependent diabetes mellitus

Antibody-dependent killer-cell activity (ADCC) was determined in 36 insulin-dependent diabetics (IDD) and 32 controls. The medians of cytotoxic indices obtained by using either antibody coated chicken red blood or HeLa cells as targets were statistically significantly reduced in the diabetics (P less than 0.05 for both systems). However, due to the wide range and considerable overlap of the cytotoxic indices observed in patients and controls, the biological significance of these mathematical differences remains to be determined. The duration of the disease did not have any influence on killer (K) cell function and only a slight tendency for decreased ADCC during episodes of poor metabolic control was noted. Further analysis of the influence of diabetes-associated factors did not reveal any definite correlation between the functional K cell deficit, the insulin dosage administered, the insulin antibody titers, the blood glucose at the time of sampling, the 24 hour glucosuria and IDD-associated immunogenetic factors.

Natural killer funciton in systemic lupus erythematosus

Peripheral blood lymphocytes from patients with systemic lupus erythematosus (SLE) demonstrated significantly less cytotoxicity against two different lymphoblastoid cell lines and one myeloid cell line than peripheral blood lymphocytes from normal individuals. Short-term culture and other attempts to remove interfering immune complexes failed to restore low natural killer (NK) function. Six day culture in fetal calf serum resulted in increased cytotoxicity by mononuclear cells from normal individuals and some SLE patients, but this effect was shown to be dependent on Fc-, not Fc+, effector cells. Suppressor cells were not demostrable as a cause for decreased NK activity.

Antibody-dependent and PHA-induced cellular cytotoxicity in rheumatoid arthritis

One hundred and thirty nine observations of antibody-dependent cell mediated cytotoxicity (ADCC) were made on 77 with rheumatoid arthritis (RA) and 17 healthy controls. There were no differences in ADCC between these 2 groups or within the RA group with regard to disease activity, duration, seropositivity, or drug treatment. Sixty observations of phytohaemagglutinin induced cytotoxicity were made on 22 patients with RA and 10 healthy controls. Again there were no differences in cytotoxicity between the 2 groups.

Behaviour of effector cells, synovial fluids, and sera from rheumatoid arthritis patients in antibody-dependent cell-mediated cytotoxicity

Antibody-dependent cell-mediated cytotoxicity (ADCC) was examined in patients with rheumatoid arthritis (RA). The cytotoxicity of peripheral blood leucocytes from patients with RA was similar to that found in normal persons, whereas ADCC was less effective in RA synovial fluid cells. It is possible that the activity in these cells is lower because of immune complexes and other factors being absorbed from the synovial fluid itself. Although patients' sera had little effect on normal peripheral blood leucocytes, synovial fluid from RA patients was markedly inhibitory in ADCC. The degree of inhibition correlated significantly with the clinical status of the patients.

Increased antibody-dependent cell-mediated cytotoxicity by monocytes from patients with rheumatoid arthritis

Antibody-dependent cell-mediated cytotoxicity (ADCC) was studied in adult patients with rheumatoid arthritis (RA) and in healthy controls. Three effector cell populations from the peripheral blood were studied which included a mixed mononuclear population, a monocyte-depleted fraction, and a monocyte-enriched fraction. The monocyte-enriched fraction from patients with RA mediated a significantly increased degree of cytotoxicity. Enhanced cytotoxicity was more evident at low effector : target ratios. There was no significant difference in ADCC activity between patient cells and control cells when either the mixed mononuclear population or monocyte-depleted population was studied as effectors. The enhanced effector function of the peripheral blood monocyte in this system may be further indication that mononuclear phagocytes are "activated" in patients with RA.

Selective decrease in antibody-dependent cell-mediated cytotoxicity in systemic lupus erythematosus and progressive systemic sclerosis

With the use of two target cells (chicken erythrocytes and Chang cells), the antibody-dependent cell-mediated cytotoxicity (ADCMC) of peripheral blood mononuclear cells from patients with systemic lupus erythematosus (SLE) and progressive systemic sclerosis (PSS) was studied. Patients with active SLE had a significant reduction in ADCMC against Chang cells whereas cytotoxicity against chicken erythrocytes did not differ significantly from that of a control population. Similarly, a group of PSS patients with positive anti-DNP antibodies demonstrated a selective reduction in ADCMC against Chang cells. These findings support the concept that different effector cells mediate ADCMC against chicken erythrocytes and Chang cells, and indicate that in some patients with SLE and PSS there is a selective reduction or blockade of the ADCMC effector cell active against Chang cells.

Lymphocyte studies in rheumatoid arthritis. II. Antibody-mediated and mitogen-induced lymphocyte cytotoxicity in synovial fluid and peripheral blood

A comparison was made of the activity of synovial fluid (SF) lymphocytes with peripheral blood lymphocytes in antibody-mediated and mitogen-induced lymphocyte cytotoxicity in patients with a variety of inflammatory joint diseases. SF lymphocytes consistently showed little or no antibody-mediated cytotoxicity (AMC) although mitogen-induced cytotoxic activity was comparable with that of the peripheral blood lymphocytes. Blocking substances on the cell surface were not responsible for the lack of AMC by SF lymphocytes as preincubation at 37 degrees C and enzyme treatment (trypsin, neuraminidase) of the cells did not restore activity. The lack of AMC by SF cells from a variety of inflammatory joint fluids demonstrates that this may be a consequence of inflammation in the joint and excludes the possibility that this is a specific property of fluids from certain conditions such as rheumatoid arthritis. Lymphocytes thought to be involved in AMC have a characteristic surface morphology (Fc receptor positive, E rosette negative, surface immunoglobulin negative). Such lymphocytes are present in synovial fluid in comparable proportions to those in blood. Hence the absence of AMC indicates that functional assays must be used in determining the presence or absence of cells with special functions.

Antibody dependent cellular cytotoxicity (ADCC) in acute hepatitis B and in chronic active hepatitis

Antibody-dependent cellular cytotoxicity (ADCC) of peripheral blood lymphocytes against chicken red blood cells (ChRBC) in the presence of specific antiserum has been studied in normal subjects and in patients with acute hepatitis B and with chronic active hepatitis (CAH). ADCC was significantly reduced in patients with acute hepatitis B studied three weeks after the onset of jaundice and in patients with CAH showing clinical, biochemical and histological features of activity. On the other hand, lymphocytes from patients with CAH in histological remission or in clinical and biochemical resolution, showed a significantly increased cytotoxicity. The effect of serum factors on ADCC of normal lymphocytes was investigated using serial serum samples from five patients with acute hepatitis B and five with CAH. Our data suggest that serum factors may be responsible for the impairment of ADCC in our patients, although other mechanisms may also be implied. Sera obtained at the time when ADCC of patients' lymphocytes was reduced, significantly inhibited ADCC of normal lymphocytes when compared with sera obtained at the time when ADCC of patients' lymphocytes was normal or increased. In all cases with CAH, the disappearance or reduction of inhibiting activity correlated with histological remission. In patients with CAH the study of serum factors inhibiting ADCC of normal lymphocytes may be a useful parameter in assessing disease activity.

Immunological and functional characteristics of peripheral blood and synovial fluid lymphocytes from patients with rheumatoid arthritis

Spontaneous (SCMC) and antibody dependent cellular cytotoxicity (ADCC); mitogenic responsiveness (PHA, Con A, PPD, dextran and pokeweed) as well as lymphocyte subpopulations (E-, EA-, EAC-rosettes, S-Ig) were studied simultaneously in peripheral blood (PBL) and synovial fluid lymphocytes (SFL) of fifteen patients with rheumatoid arthritis. Marked differences were observed in the cytotoxic activity of SFL and PBL. Whereas SCMC activity of SFL was always significantly elevated above the cytotoxic levels of PBL, the reverse was true for the ADCC reaction; here, 50% of the patients showed a decreased cytotoxicity of SFL compared to PBL. Synovial fluid neutrophils (SFN) were found to be inactive in both cytotoxic assays. No differences were found in ADCC activity of PBL between normal controls and RA patients. In SCMC assays a significantly increased activity of control PBL was only observed at L/T ratios of 100:1. Overnight incubation of PBL from RA patients and normal controls resulted in a marked decrease in SCMC and, to a smaller extent, in ADCC activity. SFL from three out of four patients lost less SCMC activity after overnight incubation than the corresponding PBL. In one patient even an increased activity in both cytotoxic systems was obtained. Regarding lymphocyte populations, T-cells were significantly decreased in PBL of RA patients. With the exception of a significantly lowered percentage of C3 receptor positive cells in SFL, no significant differences were recorded in the lymphocyte distribution between the patients' PBL and SFL. In the RA patients, the response to T-cell mitogens was significantly depressed in SFL while PPD and pokeweed reactivity was equal to that of PBL.

K-lymphocytes (killer-cells) in Crohn's disease and acute virus B-hepatitis

Total lymphocyte counts, B-, T-, C'3 receptor-bearing lymphocytes, and K-cell activity were studied in peripheral blood in patients with Crohn's disease and inflammatory liver disease. Patients with active untreated Crohn's disease and acute virus B hepatitis exhibited a markedly increased K-cell activity measured in a plaque assay when compared with normal controls (P less than 0.01). Patients with immunosuppressive treated Crohn's disease, HBsAg-positive chronic active hepatitis, and cirrhosis of the liver showed only a slight increase of K-cell activity (P less than 0.01). In the postacute phase of hepatitis (four to 12 weeks from onset) K-cell activity fell to normal levels. The number of B-lymphocytes showed a relative and absolute decrease in all groups of patients. With the exception of patients with acute HBsAg-positive hepatitis and the post-acute phase of hepatitis all the other groups showed statistically decreased absolute numbers for C'3 receptor-bearing lymphocytes. The significant decrease in K-cell activity and the number of T-lymphocytes in Crohn's disease treated with immunosuppressive drugs was interpreted as an effect of azathioprine and prednisone on these lymphocyte subpopulations.