Mechanisms of activation of human natural killer cells against tumor and virus-infected cells

Prognostic biomarkers for cholangiocarcinoma (CCA): state of the art

Introduction:Although advances in understanding the molecular basis of cholangiocarcinoma (CCA) have been made, surgery is the only curative therapy option and the overall prognosis of patients suffering from the disease remains poor. Therefore, estimation of prognosis based on known and novel biomarkers is essential for therapy guidance of CCA in both, curative and palliative settings.Areas covered:An extensive literature search on biomarkers for CCA with special emphasis on prognosis was performed. Based on this, prognostic biomarkers from serum, tumor tissue and other compartments that are currently in use or under evaluation for CCA were summarized in this review. Furthermore, an overview of new biomarkers was provided including those determined from extracellular vesicles (EVs), metabolites and nucleic acids. Finally, prognostic markers associated with potential new therapy options for the treatment of CCA were summed up.Expert opinion:So far, an optimal prognostic biomarker for CCA has not been described. However, based on the increasing knowledge about the molecular basis of CCA but also due to novel, innovative technologies, a plethora of novel prognostic biomarkers is currently under evaluation and will be available for CCA in future.

A novel bicistronic gene design couples stable cell line selection with a fucose switch in a designer CHO host to produce native and afucosylated glycoform antibodies

The conserved glycosylation site Asn²⁹⁷ of a monoclonal antibody (mAb) can be decorated with a variety of sugars that can alter mAb pharmacokinetics and recruitment of effector proteins. Antibodies lacking the core fucose at Asn²⁹⁷ (afucosylated mAbs) show enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) and increased efficacy. Here, we describe the development of a robust platform for the manufacture of afucosylated therapeutic mAbs by engineering a Chinese hamster ovary (CHO) host cell line to co-express a mAb with GDP-6-deoxy-D-lyxo-4-hexulose reductase (RMD), a prokaryotic enzyme that deflects an intermediate in the de novo synthesis of fucose to a dead-end product, resulting in the production of afucosylated mAb (GlymaxX™ Technology, ProBioGen). Expression of the mAb and RMD genes was coordinated by co-transfection of separate mAb and RMD vectors or use of an internal ribosome entry site (IRES) element to link the translation of RMD with either the glutamine synthase selection marker or the mAb light chain. The GS-IRES-RMD vector format was more suitable for the rapid generation of high yielding cell lines, secreting afucosylated mAb with titers exceeding 6.0 g/L. These cell lines maintained production of afucosylated mAb over 60 generations, ensuring their suitability for use in large-scale manufacturing. The afucosylated mAbs purified from these RMD-engineered cell lines showed increased binding in a CD16 cellular assay, demonstrating enhancement of ADCC compared to fucosylated control mAb. Furthermore, the afucosylation in these mAbs could be controlled by simple addition of L-fucose in the culture medium, thereby allowing the use of a single cell line for production of the same mAb in fucosylated and afucosylated formats for multiple therapeutic indications.

Decreased CD122 on CD56dim NK associated with its impairment in asymptomatic chronic HBV carriers with high levels of HBV DNA, HBsAg and HBeAg

AIMS

NK cells play important roles in inhibiting HBV replication and preventing HBV infection. However, NK-cell dysfunction has not been fully studied in asymptomatic chronic HBV carriers (ASC). This study aims to assess decreased expression of CD122 associated with impaired NK cells and the restoration of NK cells with IL-2 and IL-15 stimulation.

MAIN METHODS

The experiments were performed by flow cytometer, cytotoxicity assay, ELISA and western blotting.

KEY FINDINGS

The reduced CD122 on CD56⁺ NK cells and CD56^dim NK cells is associated with high levels of HBV DNA, HBsAg or HBeAg in ASCs, in which CD56^dim NK-cell impairment is observed. Moreover, decreased IFN-γ and degranulation and low cytotoxicity by CD56^dim NK cells after CD122 blockade were revealed. IL-2 and/or IL-15 can restore impaired CD56^dim NK cells, together with increased p-STAT5, which can be reversed by CD122 blockade. Additionally, IL-2 or IL-15 can enhance IFN-α2-activated CD56^dim NK-cell immune responses via up-regulating interferon alpha and beta receptor subunit 2 (IFNAR2).

SIGNIFICANCE

Down-regulated CD122 on CD56^dim NK cell in ASCs with massive viral antigens and high viremia is associated with its impairment, which can be restored by IL-2 and/or IL-15, or combined with IFN-α2.

Production of non-fucosylated antibodies by co-expression of heterologous GDP-6-deoxy-D-lyxo-4-hexulose reductase

All IgG-type antibodies are N-glycosylated in their Fc part at Asn-297. Typically, a fucose residue is attached to the first N-acetylglucosamine of these complex-type N-glycans. Antibodies lacking core fucosylation show a significantly enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) and an increased efficacy of anti-tumor activity. In cases where the clinical efficacy of an antibody is to some extent mediated by its ADCC effector function, afucosylated N-glycans could help to reduce dose requirement and save manufacturing costs. Using Chinese hamster ovary (CHO) cells as a model, we demonstrate here that heterologous expression of the prokaryotic enzyme GDP-6-deoxy-d-lyxo-4-hexulose reductase within the cytosol can efficiently deflect the fucose de novo pathway. Antibody-producing CHO cells that were modified in this way secrete antibodies lacking core fucose as demonstrated by MALDI-TOF mass spectrometry and HPAEC-PAD monosaccharide analysis. Engineering of the fucose de novo pathway has led to the construction of IgGs with a strongly enhanced ADCC effector function. The method described here should have broad practical applicability for the development of next-generation therapeutic antibodies.

Opioid-like activity of naltrexone on natural killer cell cytolytic activity and cytokine production in splenocytes: effects of alcohol

Chronic alcohol consumption has been shown to decrease the activity of natural killer (NK) cell cytolytic function and the production of various cytokines from the spleen. We have recently shown that naltrexone, an opiate receptor antagonist, when administered for a period of 2 weeks suppresses micro-opiate receptor binding but increases partial differential-opiate receptor activity in rat splenocytes. However, the effects of long-term naltrexone treatment on alcohol-induced alteration of NK cell cytolytic activity and cytokines production in splenocytes have not been determined. Male rats were pair-fed an isocaloric liquid diet or fed an ethanol-containing liquid diet for a period of 3 weeks. These rats were additionally treated after a week with a subcutaneous implant of either a naltrexone pellet or placebo pellet for 2 weeks. Splenocytes were isolated and used for determination of various cytokines interleukin (IL)-2, IL-4, and IL-6, and interferon-gamma (IFN-gamma) using enzyme-linked immunosorbent assay (ELISA), and the basal and IL-2-, IL-12-, or IL-18-induced NK cytolytic activity was measured using a standard 4-h (51)Cr release assay against YAC-1 lymphoma target cells. Ethanol consumption resulted in a reduction of the production of IL-2, IL-4, and IL-6 as well as the basal and cytokine-activated NK cell cytolytic activity and IFN-gamma production in splenocytes. Naltrexone administration increased the production of IL-2, IL-4, and IL-6 and the basal and cytokine-activated NK cell cytolytic activity and IFN-gamma production in the splenocytes of pair-fed and alcohol-fed rats. These results indicated that naltrexone treatment increases NK cell cytolytic activity and cytokine production in the spleen in vivo. Furthermore, these results identify the potential of the use of naltrexone in the treatment of immune deficiency in alcoholic and non-alcoholic patients.

Depletion of NK cells in a murine polytrauma model is associated with improved outcome and a modulation of the inflammatory response

Sepsis and associated diseases such as systemic inflammatory response syndrome and multiple organ dysfunction syndrome represent common posttraumatic complications on intensive care units induced by a variety of body defense mechanisms. Natural killer (NK) cells are part of the innate immune system. They are thought to play an important role in the development of such syndromes by interplay with other immune cell types and subsequent activation of the inflammatory cascade. To test this hypothesis, NK cells were depleted by administration of antimouse asialo-GM1 antibody in a murine polytrauma model consisting of femur fracture, hemorrhagic shock, and subsequent sepsis. Mortality and immune parameters such as cytokine expression in lung and liver, lymphocyte phenotyping, lymphocyte apoptosis, and organ pathology were determined 96 h after sepsis induction. Survival values showed 50% in the control sepsis group and 100% after NK cell depletion. Thus, NK cell depletion resulted in 50% mortality reduction. Furthermore, we found reductions in the inflammatory response, represented by IL-6 expression in liver, and a decrease in infiltrating neutrophils in the liver and lung. In addition, lymphocyte apoptosis in spleen was decreased by depletion of NK cells. Taken together, these data demonstrate that NK cells contribute to the pathogenetic pathways in a murine polytrauma model. One main mechanism of action seems to be the induction of systemic inflammatory events. Thus, depletion of NK cells results in attenuated inflammation and an overall improvement in outcome. Therefore, NK cells can be considered as important targets for therapeutic strategies.

Donor HLA-C genotype has a profound impact on the clinical outcome following liver transplantation

Late allograft dysfunction is a significant problem following liver transplantation and its pathogenesis is uncertain. HLA-C is the major inhibitory ligand for killer immunoglobulin-like receptors (KIRs) that regulate the cytotoxic activity of natural killer (NK) cells. HLA-C alleles can be allocated into two groups, termed HLA-C1 and HLA-C2, based on their KIR specificity. HLA-C2 interactions are more inhibiting to NK cell activation. We studied the clinical importance of HLA-C genotype in a large liver transplant cohort and found that possession of at least one HLA-C2 allele by the donor allograft was associated with less histological evidence of chronic rejection and graft cirrhosis, a 16.2% reduction in graft loss (p = 0.003) (hazard ratio: 2.7, 95% CI 1.4-5.3) and a 13.6% improvement in patient survival (p = 0.01) (hazard ratio: 1.9, 95% CI 1.1-3.3) at 10 years. Transplantation of an HLA-C2 homozygous allograft led to a particularly striking 26.5% reduction in graft loss (p < 0.001) (hazard ratio: 7.2, 95% CI 2.2-23.0) at 10 years when compared to HLA-C1 homozygous allografts. Donor HLA-C genotype is therefore a major determinant of clinical outcome after liver transplantation and reveals the importance of NK cells in chronic rejection and graft cirrhosis. Modulation of HLA-C and KIR interactions represents an important novel approach to promote long-term graft and patient survival.

Chronic ethanol inhibits NK cell cytolytic activity: role of opioid peptide beta-endorphin

The role of beta-endorphin (beta-EP) in ethanol-altered NK cell cytolytic activity is studied using male Fischer-344 rats as an animal model. Ethanol was administered for 1, 2, 3, or 4 wk in a liquid diet containing 8.7% ethanol (v/v), which means that 37% of the total calories were derived from ethanol. Rats treated with ethanol for 1 wk showed an increase in hypothalamic and plasma levels of immunoreactive (IR)-beta-EP, but displayed no significant effect on NK cell activity determined by (51)Cr release assay, as compared with those in pair-fed and ad libitum-fed animals. However, animals treated with ethanol for 2, 3, or 4 wk showed decreased hypothalamic and plasma levels of IR-beta-EP and decreased splenic NK cell activity. No significant decrease in the number of splenocytes and NK cells or in the percentage of NK cells was seen until after 3 and 4 wk of ethanol treatment. Exposure in vitro of splenic lymphocytes obtained from control animals to various concentrations of beta-EP increased NK cell activity. The opiate antagonist naltrexone blocked the beta-EP-stimulated effect. The in vitro NK cell response to beta-EP was reduced in the splenocytes obtained from animals treated with ethanol for 2 wk, but not in those obtained from animals treated with ethanol for 1 wk as compared with those in control animals. Additionally, beta-EP administration into the paraventricular nucleus of the hypothalamus stimulated NK cell cytolytic activity, whereas the opiate blocker administration reduced NK cell activity. The NK cell responses to paraventricular nucleus beta-EP were reduced in the animals treated with ethanol for 2 wk. These data provide evidence for the first time that ethanol inhibits NK cell cytolytic activity, possibly by reducing beta-EP-regulated splenic NK cell function.

Asbestos toxicity: an immunologic perspective

Asbestos has long been associated with a number of life threatening pulmonary diseases, including asbestosis and mesothelioma. While the lung is the primary target organ for asbestos toxicity, a number of clinical and experimental studies over the past 30 years have shown that the immune system may also be altered by exposure to asbestos at occupationally relevant concentrations. Whereas early clinical studies generally focused on systemic observations of immune alteration, more recent studies have assessed the immunological changes occurring in the lung, the primary target organ of asbestos. This review will focus on the investigations that examine the influence of asbestos on systemic and local immunity, as well as the role that the immune system may play in asbestos-related disease.

How viruses may overcome non-specific defences in the host

The pathogenicity of a virus is mainly related to its capacity to overcome the non-specific defences of a host. Fever limits the multiplication of viruses in vivo , thus allowing recovery; thermoresistant strains are virulent because they are capable of escaping the effect of hyperthermia. Resistance to the antiviral effect of interferon does not seem to exist per se but interferon may play an indirect role in virus virulence: (i) its effect may be minimized by the destruction of interferon-producing cells such as macrophages; (ii) interferon may render virus-infected target cells resistant to natural killer cell lysis. The interaction of viruses with phagocytic cells plays a predominant role; the ability to grow in macrophages or to induce macrophage blockade or paralysis may constitute a marker of virulence. This is particularly important in the liver in which the infection of Kupffer cells often represents the key event of the disease.

Treatment of virus-induced myocardial injury with a novel immunomodulating agent, vesnarinone. Suppression of natural killer cell activity and tumor necrosis factor-alpha production

Controversy still exists concerning the therapy for viral myocarditis which manifests a wide variety of clinical symptoms. Vesnarinone, a quinolinone derivative that was developed as a positive inotropic agent with complex actions, including phosphodiesterase inhibition and cation channel modification, has recently been confirmed to improve the prognosis of patients with chronic heart failure. However, the precise mechanism of this beneficial effect is not yet clearly understood. In this study, using a murine model of acute viral myocarditis resulting from encephalomyocarditis virus infection, survival and myocardial damage were markedly improved by treatment with vesnarinone. In contrast, survival was not improved by treatment with amrinone, a phosphodiesterase inhibitor. Although vesnarinone did not inhibit viral replication or protect myocytes from viral direct cell injury, it did inhibit the increase in natural killer cell activity after viral infection. On the other hand, amrinone failed to inhibit natural killer cell activity. Both vesnarinone and amrinone suppressed the production of tumor necrosis factor-alpha. Therefore, we postulate that vesnarinone exerted its beneficial effects through an inhibition of natural killer cell activity, and that it serves as an immunomodulator providing new therapeutic possibilities for the treatment of viral myocarditis and/or immunological disorders.

Effect of pharmacological purging on natural killer cell number and activity in human bone marrow

We assayed natural killer (NK) cell activity and phenotype from human bone marrow (BM) following "purge" with 4-hydroperoxycyclophosphamide (4HC) at 60 micrograms/ml for 30 min in vitro. In all cases studied, lytic activity against the K562 cell line was either significantly decreased or abolished following 4HC purge. Although NK activity was significantly affected by 4HC treatment, no major differences in the phenotype between the purged and unpurged population were seen. Further, while in vitro culture of BM with IL2 resulted in a significant increment of NK activity, no IL-2 responsive cells were found in the 4HC purged BM after 14 days of culture. This study demonstrates that pharmacological purging of bone marrow results in a persistent functional decline of NK cell activity and may serve as a useful model for the study of the ontogeny of NK cells.

A case of combined primary biliary cirrhosis, ulcerative colitis and chronic myelocytic leukemia

A rare case of primary biliary cirrhosis, ulcerative colitis and chronic myelocytic leukemia is described in a 49-year-old Japanese diabetic woman. Primary biliary cirrhosis was diagnosed by characteristic liver histology and positive serum mitochondrial antibody test. Ulcerative colitis was diagnosed by typical findings of barium enema and colonoscopy, negative fecal test for pathogens and compatible rectal histology. Chronic myelocytic leukemia was determined by representative hematologic findings and positive result for Ph1 chromosome. This is the first case with combination of primary biliary cirrhosis, ulcerative colitis and chronic myelocytic leukemia.

Modulation of human natural killer activity by vasoactive intestinal peptide (VIP) family. VIP, glucagon and GHRF specifically inhibit NK activity

Vasoactive intestinal polypeptide (VIP) is a neuropeptide, which also modulates some immune functions. Natural killer (NK) cell activity was already found to be diminished by VIP. In the present paper we report that VIP is able to decrease NK cell activity of human large granular lymphocytes (LGL), showing maximal inhibition at doses ranging from 10(-8) to 10(-6) M. Some neuropeptides, belonging to the VIP family (secretin, glucagon, peptide histidine isoleucine, PHI and human growth hormone releasing factor, GHRF), were also tested. Among these peptides, secretin and PHI were shown to be uneffective on NK cell activity whereas glucagon and GHRF were inhibitory. The D50 of GHRF was similar to that of VIP (10(-9) M), the D50 of glucagon was 10(-8) M. A recently synthesized VIP-antagonist (4Cl-D-Phe6-Leu17) was then used to assess its ability to reverse the VIP-mediated inhibition of NK activity. The antagonist was able to completely reverse the inhibitory effect of VIP on NK activity. The VIP-antagonist was also able to reverse the inhibitory effect of glucagon and GHRF, even though to a lesser extent than for VIP. Our data provide a new physiological observation regarding the functional activity of LGL, supporting the presence of a receptor for VIP on human LGL with NK activity.

Demonstration of the in vitro antiviral properties of bovine lymphokine-activated killer (LAK) cells

In cattle, cells with functional characteristics similar to those of natural killer (NK) cells are difficult to detect. However, lymphokine-activated killer (LAK) cells can be detected readily after in vitro activation of peripheral blood mononuclear leukocytes (PBML) with interleukin-2 (IL-2). In the present study, we demonstrated that IL-2-activated PBML preferentially lyse bovine herpesvirus type 1 (BHV-1)-infected cells and that the cell responsible for the lysis copurified with the cell responsible for lysis of K562. The IL-2-activated effector cells were capable of significant reducing virus production. The reduction in virus yield seemed to be by an interferon (IFN)-independent mechanism, as the amount of IFN induced in effector cells by BHV-1 was not altered by the addition of IL-2. Furthermore, enrichment of cytotoxic cells by passage through nylon wool columns removed the capability of PBML to produce IFN in response to the virus. These results suggest that activation of LAK mechanisms in cattle plays a role in controlling virus spread.

Natural killer cell number and activity in multiple sclerosis

Natural killer (NK) cell percentage among cells appearing in lymphocytic flow-cytometric gate, and their concentration per unit volume of peripheral blood, as well as NK-cell in vitro activity, were determined in 45 patients with multiple sclerosis (MS, 34 with definite and 11 with probable diagnosis). Two age- and sex-matched control groups consisted of 27 healthy individuals and 19 individuals with other neurological diseases, respectively. NK cells were identified on the basis of their reaction with monoclonal antibody NKH-1, and NK-activity on the basis of their spontaneous killing of K-562 erythroleukemia target cells with mononuclear cells from peripheral blood. MS patients were analyzed in regard to the phase (active, stable inactive, stable progressive) and course (remittent, remittent-progressive, progressive) of the disease. In general, MS patients tended to have both lower number and activity of natural killer cells than either of the two control groups. A statistically significant decrease was found for the concentration of NKH-1+ cells in the blood of all MS patients, for the number of lymphocytes in the blood of patients with remittent course of the disease, and for the number of NKH-1+ cells in the blood of patients with progressive course of the disease. It appeared that more profound defects were associated with the progression of the disease; NK-cell number always appeared more affected than NK-cell activity. In MS patients, NK-cell activity correlated significantly with NK-cell percentages among lymphocytes but poorly with the concentration of NKH-1+ cells in the blood. In healthy controls, neither of the two correlations was significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Tumor growth-promoting effect of immunosuppressive substance in mice

The effect of immunosuppressive (IS) substance obtained from cancerous ascitic fluid on tumor growth and host immunity in plasmacytoma X5563-bearing C3H/He mice is described. IS substance given in three injections, before and after tumor inoculation caused: (a) enhanced tumor growth, (b) marked reduction in survival times, (c) inhibition on Con-A response of spleen cells. Depressed natural killer (NK) activity was observed in normal and tumor-bearing mice treated with IS substance. The data presented here suggest that IS substance suppresses both humoral and cellular immunoresponsiveness and tumor cells evade immune surveillance or immunologically mediated removal.

Comparison of NK activity in mouse spleen and peripheral blood lymphocytes

Natural killer (NK) cells originating in mouse peripheral blood were studied with regard to their lytic activity against YAC-1 target cells and to their expression of asialo-GM1 marker on their surface. In Balb/c, CBA/LAK and A/J mice, PBL were found to be approximately twice as effective as splenocytes. Splenic and peripheral NK cells were shown by flow cytometry to have similar lytic potential per cell; the difference in NK activity found in the spleen and in PBL was solely due to the differences in the size of the NK cell population found in the two sites. Strain distribution of NK activity in PBL followed the same pattern observed in splenocytes. The difference in NK activity between CBA and Balb/c mice was shown to be due to the fact that the lytic potential per NK cell was approximately twice as high in the former.

Natural killer cell function in atopic dermatitis

The natural killer cell activity was studied in 41 children with mild, moderate and severe atopic dermatitis (AD) and in 37 controls. The natural killer cell function of lymphocytes was reduced in atopic children (mean +/- SD 21.92 +/- 6.18% vs. 43.87 +/- 5.80%; p less than 0.0001). This decrease was not related to the IgE serum level. A negative correlation was found between natural killer cell activity and the clinical severity of AD (r = 0.73; p less than 0.001). Natural killer cell function was re-evaluated after 9 months in 27 children during a quiescent phase of AD; it was still low, but to a lesser degree (27.66 +/- 5.42%, in the quiescent phase, vs. 43.87 +/- 5.80, controls; p less than 0.0001). The reduced natural killer cell activity seems related to the disease activity.

Distribution of natural killer cells and lymphocyte subclasses in Jessner's lymphocytic infiltration of the skin and in cutaneous lesions of discoid and systemic lupus erythematosus

We studied the cell infiltrates in biopsies from lymphocytic infiltration of the skin (LIS), with six monoclonal T cell antigen-specific antibodies and compared the reactivity pattern with those in biopsies from discoid and systemic lupus erythematosus skin lesions and allergic contact skin reactions. A newly described antibody (NK9) recognizing natural killer (NK) cells and activated cytotoxic T lymphocytes was included, and the numbers and activity of circulating NK cells was determined. Immunohistochemical staining revealed that the numbers of NK9-positive cells were highest in LIS. The distribution of T lymphocytes (OKTII + ve), helper T cells (OKT4 + ve), suppressor T cells (OKT8 + ve), Langerhans cells (OKT6 + ve) and activated T cells (anti-Tac + ve) in LIS differed from those in DLE,SLE and allergic contact reactions. However, the number of circulating NK cells (large granular lymphocytes) and the NK activity in peripheral blood were normal in LIS. We conclude that in LIS a distinct type of T cell activation occurs; the cause of this remains to be determined.

The relationship between natural killer cell activity and delayed-type hypersensitivity reaction to 2,4-dinitrochlorbenzene in the spectrum of chronic, intractable pulmonary tuberculosis

We examined natural killer (NK) cell activity and delayed-type hypersensitivity reaction to 2,4-dinitrochlorbenzene (DNCB) in the spectrum of chronic, intractable pulmonary tuberculosis. A high reactive group as defined by high NK cell activity and positive reaction to DNCB were characterised by stable clinical courses assessed by radiographical and clinical changes. A low reactive group defined by non-augmented NK cell activity and negative reaction to DNCB were characterised by progressive clinical courses. Although far advanced radiographic lesions were observed more frequently in the low reactive group and moderately advanced lesions more frequently in the high reactive group, there was not a significant statistical trend.

Induction of interferon production by natural killer cells by organogermanium compound, Ge132

Interferon (IFN)-inducing activity of the organogermanium compound Ge132 in human peripheral mononuclear cells was investigated. By using Percoll discontinuous density gradient centrifugation, peripheral blood nonphagocytic and nonadherent mononuclear cells were divided into the low-and high-density fractions. Natural killer (NK)-enriched low-density fractions, but not the T-cell-enriched high-density fractions, showed IFN production by the stimulation of Ge132. The maximal titer of IFN by NK-enriched fractions (F1 + F2) was observed after a 74-h cultivation in the presence of 200 micrograms/ml Ge132. IFN production by the NK-enriched fractions was abrogated by treatment of the cells with monoclonal antibody against human NK cells in the presence of complement. The treatment with antiserum-neutralizing human IFN-gamma resulted in a marked reduction, indicating that a major part of IFN was IFN-gamma. These results suggested that Ge132 might possess affinity to NK cells, inducing IFN production by NK cells.

Influenza viral glycoproteins induced cell-mediated cytotoxicity by an interferon-independent mechanism

Human natural killer (NK) cells exposed to the influenza surface antigen neuraminidase (NA) show high cytotoxic activity, as evaluated using chromium-labeled K562 target cells in a standard overnight cytotoxicity assay. The role of interferon (IFN) in the stimulation of NK cells was examined by using three separate approaches. The use of appropriate antibodies to check IFN- and NA-specific cell-mediated cytotoxicity (CMC) stimulation showed that antibodies to IFN (-alpha, -gamma) did not alter NA-induced CMC, and vice versa. The treatment of NK cells with actinomycin D, before or after stimulation with IFN and NA revealed that only IFN-induced CMC was inhibited (50 to 100%). However, NK cells that were stimulated with NA before their exposure to actinomycin D became susceptible to stimulation by IFN. The interaction kinetics between IFN and NA demonstrated the presence of two mechanisms of CMC stimulation. Taken together, the results clearly show that stimulation of CMC by a viral component is effected through an IFN-independent pathway, and that this mechanism is probably followed by IFN under certain conditions.

Production of interferon alpha and interferon gamma by peripheral blood leukocytes from patients with chronic hepatitis B virus infection

Peripheral blood leukocytes from patients with chronic hepatitis B virus (HBV) infection were studied for their capacity to produce interferon (IFN) alpha or IFN gamma. Yields of IFN alpha in leukocyte cultures stimulated with influenza A virus or human leukemic cells were significantly lower than those obtained from healthy controls. Production of IFN gamma in response to induction with protein A of Staphylococcus aureus was also significantly diminished. Defects of IFN production in leukocyte cultures showed no correlation with active viral replication or the degree of severity of HBV-associated liver disease. The demonstration of partial defects of endogenous IFN production provides a rationale for using IFN replacement therapy in patients with chronic HBV infection.

Impaired natural killer cell activity in Bloom's syndrome could be restored by human recombinant IL-2 in vitro

Natural killer (NK) activity against K562 tumor cells was evaluated in peripheral blood nonadherent mononuclear cells (PBMNC) obtained from four patients with Bloom's syndrome. NK activity of PBMNC from all patients was found to be depressed to less than half of age-matched control values. However, all patients showed the normal percentages of large granular lymphocytes and of cells expressing the NK-cell-associated determinants (OKM1, Leu-7, and Leu-11). Although recombinant interferon-beta or -gamma augmented NK activity of patients' PBMNC in a manner similar to their effects on NK activity of normal individuals, impaired NK activity of PBMNC from Bloom's patients could be restored to normal ranges only by recombinant interleukin 2 (IL-2). These results suggested that IL-2 and interferons might participate in boosting NK activity of Bloom's syndrome in different ways.

In vivo activation of murine natural killer cell functions by human recombinant DNA interleukin 2

Intraperitoneal (i.p.) injections of purified human recombinant DNA (rDNA)-interleukin 2 (IL 2) resulted in in vivo activation of local natural killer (NK) cell activities in wild-type and congenitally athymic mice. NK cells were identified by short-term cytotoxicity assays against YAC tumor targets and by cell-surface phenotyping. The magnitude of the cytolytic responses was dependent on the IL 2 dose (greater than or equal to 0.1 microgram per injection) and the time period of treatment (the maximum response was on days 3 to 4 after daily treatment). In vivo application of antisera against the murine NK marker asialo GM1 (asGM1) and against interferon-alpha/beta and -gamma (IFN) significantly inhibited NK cell activation. Limiting dilution analysis revealed high frequencies (up to 1 in 1.8 X 10(3)) of in vitro IL 2 reactive mononuclear cells among the peritoneal exudate cells (PEC) of normal mice. rDNA-IL 2 activated non-adherent PEC to proliferate. The majority of these cultures also displayed cytotoxicity against YAC targets. No exogenous IFN was required for either response. Endogenous IFN production did not appear to play an important role for induction of cytotoxicity in this system either. Only a minority of cultures produced measurable levels of IFN without showing excessive cytotoxic activity. In vivo IL 2 treatment resulted in a rapid increase of the total numbers and frequencies of the IL 2 reactive PEC. Hence, IL 2 alone was apparently sufficient for in vitro activation of NK-like activities, whereas IFN-induction by IL 2 was required for in vivo elicitation of similar responses in perhaps the same cell populations.

Reduced killer cell activity of lymphocytes from patients with asbestosis

Immunological abnormalities in 30 patients with asbestosis were investigated by examining the cytoxicity of natural killer (NK) cells and antibody dependent cellular cytotoxicity by killer (K) cells from peripheral blood lymphocytes; the effects of interferon on NK activity was also examined. Fifteen men and 15 women (mean age 58; range 40-72) with asbestosis but who were free of complications such as tuberculosis, carcinoma, or steroid treatment were the subjects for study. There were nine cases of type 1, 19 cases of type 2, and two cases of type 3 disease as described in the ILO classification of pneumoconiosis. They were all textile workers with a mean duration of 18 years (3-40 years) since first exposure to chrysotile. Controls matched for age and sex were selected from a population without occupational exposure to asbestos. The activity of the NK and K cells in patients with asbestosis was significantly lower than in the control group, but the populations of NK and K cells in the peripheral blood lymphocytes were not significantly different in the two groups. An in vitro experiment showed that the increase in the cytotoxicity of the NK cell after treatment with interferon-alpha was significantly lower in the subjects than in the controls. These results indicate that one of the defence mechanisms in relation to cancer is deficient in patients with asbestosis.

Cytotoxic lymphocytes generated in vivo with acute measles virus infection

We studied the generation of cytotoxic lymphocytes in adults during an outbreak of acute measles virus infection. Nine patients were studied determining in particular whether virus-specific cytotoxic T lymphocytes could be directly detected in peripheral blood during this acute infection. The cytotoxicity of PBL was assayed against measles virus-infected and uninfected phytohemagglutinin-induced blast cells of matched and mismatched HLA, A, B, and C types, in a standard 4-h 51Cr release assay. There was greater cytotoxicity against measles virus-infected than uninfected target cells in at least one sample from every patient. In 4 patients this preferential lysis of virus infected cells was greater (a difference of more than 10% virus-specific lysis) against HLA-matched than mismatched targets. This preference for HLA A and B matched infected target cells was also clearly seen when the effector PBL were depleted of FC receptor bearing cells. The other 5 subjects exhibited no evidence of preferential lysis of HLA-matched measles virus-infected cells. All 9 patients limited the spread of measles virus infection and recovered equally from the acute infection. These studies provide some evidence to suggest that MHC-restricted virus-specific CTL are detectable in human peripheral blood during acute measles virus infection, albeit only with low frequency, but are not necessarily associated with recovery from disease.

In vitro enhancement of human natural cell-mediated cytotoxicity by purified influenza virus glycoproteins

The role of the glycoproteins of influenza virus, hemagglutinin (HA), and neuraminidase (NA) in the in vitro stimulation of natural cell-mediated cytotoxicity (NCMC) or natural killer activity of human peripheral blood lymphocytes was evaluated with radiolabeled K562 cells as target cells in an overnight chromium release assay. Three different approaches were used. (i) Purified viral proteins were obtained by extraction with Nonidet P-40, separation on a sucrose gradient, and further purification by affinity chromatography. Ficoll-Hypaque-purified peripheral blood lymphocytes exposed to HA or NA individually or to a mixture of both significantly increased NCMC (32 to 50%). (ii) Treatment of HA and NA with their respective homologous antisera or F(ab')2 antibody abrogated the stimulation of NCMC by these glycoproteins. (iii) Virions treated with proteolytic enzymes resulted in viral cores lacking either HA or NA or both activities. Compared to whole virions, viral cores devoid of HA activity only induced a 50% increase in NCMC, whereas viral cores lacking HA activity and with traces of NA activity stimulated only 10% of the NCMC. These results suggest that influenza virus-induced cell-mediated cytotoxicity is largely due to its glycoproteins.

The role of viral glycoproteins in mumps virus-mediated antibody-dependent cellular cytotoxity in vitro

Treatment of human peripheral blood lymphocytes with live or UV-inactivated mumps virions enhances antibody-mediated cellular cytotoxicity (ADCC), reflected by increased target cell lysis in a 51Cr-release assay or an increased number of plaque-forming cells on monolayers of bovine erythrocytes (Eb) in the presence of anti-Eb antibodies. Virus treatment of the Eb targets causes a similar enhancement. The role of viral glycoproteins in ADCC enhancement was investigated by using a panel of monoclonal antibodies raised in mice against mumps virions. Most of the lymphocytes bound mumps virions, as ascertained by indirect immunofluorescence. A high proportion of virus-treated lymphocytes also formed rosettes with Eb. Anti-HN antibodies inhibited rosetting to various degrees. Although antibodies with high haemagglutination inhibition titres were most efficient inhibitors, antibodies without this serological activity were also inhibitory. Anti-F antibodies were only weakly inhibitory, and anti-NP antibodies had no effect. Anti-HN antibodies also abrogated target cell lysis in the 51Cr-release assay and effector cell recruitment in the ADCC plaque assay by inhibiting virus-mediated Eb-lymphocyte interactions both at the target cell and at the effector cell level. Anti-F or anti-NP antibodies were only weakly or not at all inhibitory. The results suggest that virus-mediated enhancement of ADCC is caused by the HN glycoprotein, primarily (although perhaps not exclusively) by its improvement of the effector cell-target cell contacts necessary for the efficient execution of target cell lysis.

Results of space experiment program "Interferon"

The results of the biological space experiment "Interferon" performed by two international cosmonaut teams (26 May 1980, and 16 May 1981) aboard space laboratory Solyut-6 are reported: (1) Human lymphocytes separated from blood of healthy donors and placed into "Interferon I" equipment could be kept for 7 days in suspension culture under spaceflight conditions. Interferon production could be induced in human lymphocytes by preparations of different origin: virus, synthetic polyribonucleotides, bacterial protein and plant pigment. An increased lymphocyte interferon production in space laboratory compared to ground control was observed. (2) Human interferon preparations and interferon inducers placed in space laboratory at room temperature for 7 days maintained their biological activity. (3) A decrease of induced interferon production and natural killer activity of lymphocytes isolated from peripheral blood of cosmonauts was observed on the 1st day on Earth after 7-days spaceflight.

Modulation of natural killer (NK) cells by autologous neutrophils and monocytes

Although natural killer (NK) cell activity is remarkably stable in healthy individuals, the number and cytotoxicity of the cells fluctuate in disease. In man, regulatory mechanisms are virtually unexplored but depressed NK cell function accompanies most chronic diseases. A suppressive role of monocytes/macrophages has been reported. Since neutrophils (PMN) and monocytes (M) often respond reciprocally to pathologic stimuli, experiments were designed to investigate whether increments in PMN and M per se could influence NK cell function. Peripheral blood NK cells obtained by Percoll gradient centrifugation were either cocultured with various concentrations of autologous PMN or M or they were exposed to diffusates of these granulocytes in Millipore chambers. The treated NK cells were washed and then mixed with melanoma target cells in various effector:target cell ratios. It was observed that PMN diffusates augmented cytotoxicity whereas monocyte diffusates decreased the killing function of NK cells markedly and in a dose dependent fashion (P less than 0.001). The stimulatory effect of PMN diffusates was heat labile and not attributable to interferon. The inhibitory effect of M diffusates was heat stable, not due to prostaglandins or lysozyme, and irreversible within 6 hr of observation. Binding of effector to target cells was enhanced by PMN-media, and significantly inhibited by monocyte diffusates . It is therefore possible that factors elaborated by neutrophils and monocytes in vivo could also influence NK cell function.

Cytotoxic activity of peripheral blood and cerebrospinal fluid lymphocytes from patients with multiple sclerosis and other neurological diseases: analysis at the single cell level of the relationship of cytotoxic effectors and interferon-producing cells

The production of interferon (IFN alpha) in relationship to NK and ADCC activity of peripheral blood and cerebrospinal lymphocytes was examined at the single cell level in patients with multiple sclerosis (MS) and other neurological diseases (OND) compared with age- and sex-matched controls. IFN-producing cells were assessed by indirect immunofluorescent scoring of cytoplasmic IFN+ cells. Peak production of cytoplasmic IFN alpha in nylon wool-passed ( NWP ) cells occurred between 5 and 17 hr in vitro under the inductive stimulus of MOLT 4, K562, or antibody-coated Chang liver cells. The proportion of K562- and MOLT 4-induced IFN alpha-positive cells in the total lymphocyte and target-binding cell (TBC) population was significantly lower in MS NWP -peripheral blood lymphocytes (PBL) than in OND and normal controls; this was in direct relationship to a decreased percentage of NK cells in MS PBL. In contrast MS cells responded the same as controls (total IFN+ cells) or higher than controls (IFN+-TBC) after IFN alpha induction by antibody-coated Chang, the ADCC target, in parallel with elevated ADCC activity by MS PBL. MS CSF contained a higher proportion of total IFN+ cells but a similar proportion of IFN+-TBC as their homologous NWP PBL population. In OND CSF, both the percentage of total IFN+ and the percentage of IFN+-TBC were higher than in OND blood and higher than their respective MS CSF populations. The relationship of IFN-producing cells in the central nervous system (CNS) to putative cytotoxic cells is discussed.

Age-related decline of human interferon alpha and interferon gamma production

The influence of donor age on the production of interferon (IFN) alpha and IFN gamma by human peripheral blood mononuclear cells in vitro has been studied. The results demonstrate an age-related decline of the capacity to synthesize and secrete antiviral activity. Yields of virus-induced IFN alpha and lectin-induced IFN gamma were significantly decreased in mononuclear cell cultures from older subjects (greater than 50 years) when compared to those of younger subjects (less than 50 years). The observed deficiency of IFN production may be involved in the increased susceptibility of aged humans to viral infections and malignant diseases.

An evaluation of the maternal natural killer cell population during the course of murine pregnancy

Earlier work from this laboratory revealed an increase in the level of null (Thy-1-, IgM-) lymphocytes in the maternal lymphoid organs during the first pregnancy in the mouse that was more pronounced during allogeneic pregnancy than during syngeneic pregnancy. In view of the suggestive evidence for the bone marrow origin of these null cells, the functional significance of the null cell rise was explored in this study by an examination of (1) splenic NK activity as measured by the 51Cr-release assay using YAC-1 lymphoma targets, (2) the incidence of NK lineage cells in the spleen as measured by the ability of splenic null lymphocytes to bind YAC-1 lymphoma targets, and (3) the possible presence of a NK target structure on placental trophoblast cells, studied with a cold target competition assay. Results revealed that the absolute levels of null lymphocytes, NK lineage cells, and NK activity in the spleen increased moderately and nearly at the same time during syngeneic pregnancy. During allogeneic pregnancy all three parameters increased more significantly, the rise in the levels of NK activity and NK lineage cells somewhat preceding the null cell rise, suggesting preferential recruitment of active NK cells within the null lymphocyte population of the spleen. Trophoblast cells appeared to share NK target structures with YAC-1 lymphoma cells, suggesting that a rise in the NK cell level in both pregnancy types may represent a response of the mother to such target structures. Since the density of such moieties was similar for homozygous and heterozygous trophoblasts, a higher NK cell response during allogeneic pregnancy is considered to result indirectly from an alloreactive response of the mother to the paternally encoded antigens on the fetoplacental unit, possibly from a stimulation of interferon producing cells such as macrophages. Nevertheless, such a response appears to be harmless for the allogeneic conceptus.

Serum interferon levels and natural killer cell activity in patients with asbestosis

Natural killer cell activity and serum interferon levels were measured in 30 patients with asbestosis. The chest radiographs showed type 1 changes (ILO pneumoconiosis classification) in nine, type 2 changes in 19, and type 3 changes in two. Thirty control subjects matched for age, sex, and smoking habit were also studied. Patients with asbestosis had significantly higher serum interferon levels than the controls. There was no significant difference in natural killer cell activity between patients with asbestosis and normal controls.

Interferon-induced cytotoxicity and (2'-5') oligo(A) synthetase activity in T cells. Differences in responsiveness among T cells from various individuals and among lymphoblastoid T-cell lines

Peripheral blood T lymphocytes became cytotoxic toward Daudi lymphoblastoid cells when incubated in vitro with interferon (IFN). The degree and rate of response to IFN varied markedly from one blood donor to another. "Low responders," who reproducibly showed a slower response to IFN, as well as "high responders" could be identified. The rate of increase in (2'-5') oligo(A) synthetase activity in IFN-treated cells also varied and appeared to correlate to the rate of increase in cytotoxicity. Three lymphoblastoid T-cell lines (Molt 4, Peer, HPB-ALL) also became cytotoxic towards Daudi cells when incubated with IFN and in these cells too the rate of induction of cytotoxicity appeared to correlate to the rate of increase in (2'-5') oligo(A) synthetase activity. Differences in responsiveness of T cells to IFN-mediated cytotoxicity might, therefore, reflect differences in responsiveness to IFN in general. Thus, quantitation of these differences might yield useful information for assessing the dosage and frequency of IFN administration to patients undergoing therapy.

Antiviral and antiproliferative effects of interferons delivered via monoclonal antibodies

We present in vitro experiments demonstrating the feasibility of specifically targeting IFNs by coupling to monoclonal antibodies (MAbs). Human interferon alpha (HuIFN-alpha), both natural and recombinant, were coupled to Epstein-Barr virus (EBV) membrane antigen (MA) specific MAbs and shown to retain full antiviral and antiproliferative activities when tested on several human cell lines. A series of in vitro pulsing experiments demonstrated that a minimum amount of MAb-delivered IFN exerts pronounced antiviral and antiproliferative effects on human QIMR-WIL target cells which carry EBV (viral) membrane antigens (EBV-MA+) and not on U-266 or Hep2 cell lines (EBV-MA-). Additionally the antiproliferative action of MAb-coupled rIFN-alpha appeared to be enhanced compared with that of uncoupled.

Supplement-induced cytotoxic cells (SICC) generated from mouse thymus or spleen cells cultured in the presence of interleukin 2 and/or polyinosinic acid

Mouse thymocytes and spleen cells from unprimed C57BL/6 donors generate broadly reactive cytotoxic cells during 5 days of culture in vitro with polyinosinic acid (5') (poly(I] and/or supernatant from PMA-treated EL4 leukemia cells which contains interleukin 2 (IL-2) activity. We refer here to such cytotoxic cells as "supplement-induced cytotoxic cells" or SICC. Thymocytes are dependent on the supernatant factor(s), whereas spleen cells are usually stimulated by poly(I) alone. Polyinosinic acid acts synergistically with supernatant factor(s) to stimulate generation of SICC by both thymocytes (SICC-T) and spleen cells (SICC-S) when the IL-2 activity of the supernatant is inadequate alone. SICC can be generated by both splenocytes and thymocytes in medium supplemented with fetal calf serum or syngeneic plasma. SICC are active in 4 hr 51Cr-release tests against syngeneic, allogeneic, and xenogeneic tumors but not against lipopolysaccharide-induced lymphoblasts. Embryonic fibroblasts, too, are sensitive to SICC generated by thymocytes. In complement-dependent depletion tests, cytotoxic activity is partially sensitive (SICC-T) or fully sensitive (SICC-S) to anti-Thy-1 and -H-2 but not to anti-Lyt-1, -Lyt-2, or -asialo GM1.

Abnormal serum factors in Guillain-Barré syndrome

The Guillain-Barré Syndrome (GBS) is generally considered to be a cell-mediated immunopathologic disease of the peripheral nervous system (PNS), although the evidence for this is indirect. Both in vitro and in vivo studies of sera from experimental animals with autoimmune demyelinating neuropathies suggest that serum factors, including antibodies to PNS myelin and/or Schwann cells, may be important in the pathogenesis of some of these disorders. More recently, similar in vitro and in vivo techniques, including the production of demyelination following intraneural injection in the rat have been employed to study sera from patients with GBS. The results of these studies demonstrate the presence of factor(s), as yet not fully characterized, that may be important in mediating demyelination. Moreover, in some patients with chronic or relapsing demyelinative inflammatory neuropathies and monoclonal gammopathy, there is evidence of antimyelin antibodies to PNS myelin. Further studies of serum from patients with acute GBS and these other neuropathies may clarify the role of serum factors in acquired inflammatory diseases of the PNS.

Interferon production by human marrow stromal cells

We have demonstrated that normal human bone marrow stromal cells can be induced to produce high levels of beta-interferon (IFN). One of three randomly selected human stromal cell lines produced beta-IFN in similar amounts to one of the best beta-IFN producer cell lines produced beta-IFN in similar amounts to one of the best beta-IFN producer cell lines (MG-63 osteosarcoma cells). The marrow stromal cell lines did not produce gamma-IFN, though a low level of alpha-IFN was apparently produced. The stromal cell lines differ from usual producer cell lines in that they can be subcultured for a much longer growth period and also maintain the ability to producer IFN. The cells are karyotypically normal and are not virus transformed. Such cell lines may be useful in the production of human IFN as well as allowing studies on the role of IFN in stromal cell-haemopoietic cell interactions.

Natural cytotoxicity in malignant and premalignant cervical neoplasia and enhancement of cytotoxicity with interferon

Natural cytotoxicity was measured in 70 women with cervical dysplasia or invasive cervical cancer and in 13 controls, using a short-term chromium release assay. A significant diminution in mean cytotoxicity was found in women with CIN III and with advanced cervical carcinoma. When the peripheral blood leukocytes of patients and controls were pretreated with interferon, there was significant enhancement of the mean cytotoxicity for all groups except those with advanced cervical carcinoma (stage IIB or worse). Our results have shown a significant defect in a potentially important immune surveillance mechanism in a group of patients with premalignant disease at risk for the development of invasive cancer. A possible role for interferon in the treatment of cervical intraepithelial neoplasia is suggested.

The chemiluminescence response of human natural killer cells. II. Association of a decreased response with low natural killer activity

Low natural killer (NK) responders selected from a panel of 600 normal, healthy volunteers exhibited 5- to 10-fold less cytotoxicity against the human erythroleukemic cell line K562, compared with high NK responders. Antibody-dependent cellular cytotoxicity against tumor cells, which is mediated by similar or identical effectors, was also depressed in low NK donors whereas lectin-dependent T cell killing and monocyte-mediated cytolysis of tumor cells was normal. Low NK donors exhibited normal frequencies of cells expressing the HNK-1 marker of human NK cells and highly enriched NK fractions were not impaired in their ability to recognize and bind to NK-sensitive target cells. Interferon partially activated low responder NK cells but did not restore the response to normal levels. The burst of chemiluminescence that is generated by NK cells within seconds of target cell contact was markedly impaired in low NK responder donors. We have previously shown that chemiluminescence detects reactive oxygen intermediates which are necessary but not sufficient for the activation of the NK cytolytic pathway.

Characterization of the human peripheral blood effector cells mediating antibody-dependent cell-mediated cytotoxicity against respiratory syncytial virus

Peripheral blood lymphocytes were separated into several subpopulations and evaluated for their ability to mediate antibody-dependent cell-mediated cytotoxicity (ADCC) against respiratory syncytial virus (RSV)-infected HeLa cells. Using erythrocyte rosetting methods, nylon wool filtration, and cytolysis with OKT-3 monoclonal antibody, two lymphocyte subpopulations were shown to mediate RSV-ADCC; non-T, non-B, and IgG-Fc receptor-bearing lymphocytes and E-rosetting cells with IgGFc receptors (T gamma cells). Removal of phagocytic cells did not alter ADCC activity. Monoclonal antibody to human NK and K cells, HNK-1, recognized these two lymphocyte effector subpopulations.

Effect of interferon on cell proliferation and generation of cytotoxic potential in mixed autologous and allogeneic lymphocyte cultures

Autologous and allogeneic mixed lymphocyte cultures (AMC and MLC) were assayed for blastogenesis, generation of cytotoxic potential, and the effect of interferon (IFN-alpha) on these features. The cells of the mixed cultures lysed K562, Daudi, and autologous and allogeneic phytohaemagglutinin blasts. Stimulator-specific cytotoxicity was observed only in MLC. B blasts induced with Staphylococcus aureus were only affected in a stimulator-specific manner. Short-term IFN treatment of the MLC-derived effectors before the lytic assay enhanced the nonspecific component of cytotoxicity. Cell proliferation was considerably lower in AMC than in MLC. This was decreased when IFN-alpha was added at the initiation of the cultures. The presence of IFN influenced the generation of lytic potential. Comparison of the lysis of the different targets exerted by MLC-activated cells suggested that the specific component was more substantially elevated than the nonspecific one. It is likely that the IFN induced such modifications in the culture conditions that favoured the proliferation of the specific clone. Re-exposure of lymphocytes cultured in the presence of IFN to another dose of IFN before the assay had no influence on their lytic potential.

Lymphocytotoxicity against autologous hepatocytes and membrane-bound IgG in viral and autoimmune chronic active hepatitis

Membrane-bound IgG and lymphocytotoxic activity of total, T-enriched and T-depleted lymphocytes, using autologous hepatocytes have been evaluated in: (a) 31 patients with chronic active hepatitis (CAH) (six autoimmune and 25 hepatitis B virus - HBV-related); (b) five patients with inactive alcoholic cirrhosis; and (c) nine subjects with normal hepatic histology. Lymphocytotoxicity was positive in 83% of autoimmune CAH and 68% of HBV-related cases; it was confined to the T-depleted subpopulation in the first group, while it was present in both the T-enriched and T-depleted subpopulations in 81% of HBV-related cases. Membrane-bound IgG was present in 58% of group (a) and in none of the other groups. A linear pattern was found in four out of five autoimmune CAH patients with positive lymphocytotoxic activity. The autoimmune patient with lymphocytotoxic activity within the normal range did not show any membrane fluorescence. Among HBV-related CAH patients, 13 presented a granular pattern, two an associated granular and linear pattern and ten were negative. These data suggest that different lymphocytotoxic mechanisms are involved in the two forms of CAH studied.