Supernatants of human leukocytes contain mediator, different from interferon gamma, which induces expression of MHC class II antigens

A Rare Case of Acquired Factor VIII Deficiency in an Elderly Male With a History of Rheumatoid Arthritis

Acquired hemophilia A (AHA) or factor VIII (FVIII) deficiency is caused by autoantibodies targeting FVIII in the blood coagulation pathway; it is a rare condition making it challenging to diagnose. A timely diagnosis is crucial, without which there is a risk of catastrophic bleeding. We report a case of a patient with a history of duodenal arteriovenous malformations, previously on apixaban, who presented with four days of melena. On admission he was found to have a hemoglobin of 5.7 and elevated partial thromboplastin time (PTT), promoting further workup showing FVIII levels of <1%, with a mixing study that failed to correct suggesting the presence of inhibitors against FVIII. Other characteristics of this patient's cases included controlled rheumatoid arthritis without detectable rheumatoid factor or increased erythrocyte sedimentation rate (ESR). The patient was initially treated with prednisone and intravenous immunoglobulins, but an insufficient response prompted the initiation of recombinant factor VII, rituximab, and cyclophosphamide during hospitalization.

Isolation of human antibodies to tumor-associated endothelial cell markers by in vitro human endothelial cell selection with phage display libraries

Human antibodies selectively targeting angiogenic vessels hold great promise for the immunotherapy of human malignancies and can help to elucidate the molecular mechanisms regulating angiogenesis. By selecting a large antibody phage display library on proliferating stimulated HUVEC, we have isolated 15 human antibodies that bind to HUVEC in flow cytometric analysis, 11 of which target the vasculature of colorectal carcinomas as demonstrated by immunohistochemical analysis. The four most specific antibodies, TEM-A, TEM-C, TEM-M and TEM-Q, also stain the vasculature of a series of carcinomas derived from liver, ovary, kidney, bladder, lung and breast, and either react weakly or not all with the vasculature of corresponding normal tissues. All four antibodies react with the vasculature of endometrium, but only TEM-M and TEM-Q react with the vasculature of placenta. As shown by non-reducing western blot analysis, 9/15 of the antibodies recognize either one or two distinct bands on HUVEC cell lysates, with molecular weights of 175 and/or 110-125 kDa. Antibodies identified by this approach may be used for the identification of new markers of angiogenesis and/or tumor vasculature. The selected antibodies may prove useful as new prognostic markers, for in vivo tumor imaging purposes and for further development of targeted therapies.

Results from a human renal allograft tolerance trial evaluating the humanized CD52-specific monoclonal antibody alemtuzumab (CAMPATH-1H)

BACKGROUND

Profound T-cell depletion before allotransplantation with gradual posttransplant T-cell repopulation induces a state of donor-specific immune hyporesponsiveness or tolerance in some animal models. Alemtuzumab (Campath-1H, Millennium Pharmaceuticals, Cambridge, MA) is a humanized CD52-specific monoclonal antibody that produces profound T-cell depletion in humans and reduces the need for maintenance immunosuppression after renal transplantation. We therefore performed a study to determine if pretransplant T-cell depletion with alemtuzumab would induce tolerance in human renal allografts and to evaluate the nature of the alloimmune response in the setting of T-cell depletion.

METHODS

Seven nonsensitized recipients of living-donor kidneys were treated perioperatively with alemtuzumab and followed postoperatively without maintenance immunosuppression. Patients were evaluated clinically by peripheral flow cytometry, protocol biopsies evaluated immunohistochemically, and real-time polymerase chain reaction-based transcriptional analysis.

RESULTS

Lymphocyte depletion was profound in the periphery and secondary lymphoid tissues. All patients developed reversible rejection episodes within the first month that were characterized by predominantly monocytic (not lymphocytic) infiltrates with only rare T cells in the peripheral blood or allograft. These episodes were responsive to treatment with steroids or sirolimus or both. After therapy, patients remained rejection-free on reduced immunosuppression, generally monotherapy sirolimus, despite the recovery of lymphocytes to normal levels.

CONCLUSIONS

T-cell depletion alone does not induce tolerance in humans. These data underscore a prominent role for early responding monocytes in human allograft rejection.

Angiogenesis inhibitors overcome tumor induced endothelial cell anergy

We report here that tumor angiogenesis-mediated endothelial cell (EC) anergy can be overcome by inhibitors of angiogenesis. We found previously that tumor growth, known to be dependent on angiogenesis, results in down-regulation of endothelial adhesion molecules and tumor EC anergy to inflammatory signals. We hypothesized that counteracting angiogenesis induces re-expression of adhesion molecules and normalizes responses to inflammatory cytokines. Here, we present data to show that the angiogenesis inhibitor platelet factor-4 (PF4) is able to prevent basic fibroblast growth factor (bFGF)-induced down-regulation of intercellular adhesion molecule-1 (ICAM-1). Furthermore, PF4 restores ICAM-1 expression following bFGF-induced down-regulation of ICAM-1. This PF4 effect occurs at the protein level and the RNA level and it has functional impact on leukocyte adhesion. In addition, PF4 overcomes the tumor-induced EC anergy to inflammatory signals such as tumor necrosis factor alpha (TNF alpha). Our findings may be the basis of new cancer therapies by combining anti-angiogenic therapy and immunotherapy to decrease blood vessel formation and to increase the effectiveness of inflammatory reactions against tumors.

Endothelial CD34 is suppressed in human malignancies: role of angiogenic factors

We report the suppressed vascular CD34 expression in renal cell carcinoma. This was found by quantitatively analyzing CD34 expression on normal and tumor derived EC by flow cytometry. In vitro studies revealed that culture of umbilical cord or dermis derived microvascular EC with angiogenic factors such as basic fibroblast growth factor (bFGF) and vascular endothelial cell growth factor induced downregulation of CD34. This angiogenesis-induced downregulated expression of CD34 adhesion molecule may contribute to the tumor mediated escape mechanism from immune surveillance. It is concluded that there are quantitative differences in expression of endothelial CD34 in different compartments of the vasculature, that angiogenic factors affect this expression and that subpopulations of EC exist with differences in EAM expression.

CD44 Is Involved in Tumor Angiogenesis; an Activation Antigen on Human Endothelial Cells

CD44 is described to be an activation molecule in a number of different cell types. We investigated the role of CD44 on human endothelial cells (EC) and in tumor angiogenesis. Using flow cytometry we showed that EC from the vasculature of human solid tumors display an enhanced expression of CD44 as compared to EC from normal tissue. This finding was confirmed by immunohistochemical studies on frozen tissue sections. Because tumors are dependent on angiogenesis, the role of angiogenic stimuli in the enhanced CD44 expression was investigated. We found that basic fibroblast growth factor (bFGF ) and vascular endothelial growth factor were able to efficiently upregulate CD44 expression on cultured human EC. The upregulation reached maximal levels after treatment for 3 days with 10 ng/mL bFGF. The physiological impact of this upregulation was shown by the enhanced binding of EC to hyaluronate after pretreatment with bFGF. In a next set of studies that were designed to unravel the regulation of CD44 expression on EC we concluded that CD44 is an activation antigen on human EC since (1) human umbilical vein derived endothelial cells, which in vivo do not express CD44, begin to express CD44 when plated and cultured, (2) CD44 expression is enhanced after subculture of confluent cultures, (3) CD44 is predominantly expressed on the BrdU incorporating subset of cultured EC. The specific expression of CD44 on activated and tumor EC prompted us to study the usefulness of CD44 as an endothelial target for therapy with immunotoxins. In vitro experiments showed that EC are efficiently killed after targeting immunotoxin to CD44.

CD44 Is Involved in Tumor Angiogenesis; an Activation Antigen on Human Endothelial Cells

CD44 is described to be an activation molecule in a number of different cell types. We investigated the role of CD44 on human endothelial cells (EC) and in tumor angiogenesis. Using flow cytometry we showed that EC from the vasculature of human solid tumors display an enhanced expression of CD44 as compared to EC from normal tissue. This finding was confirmed by immunohistochemical studies on frozen tissue sections. Because tumors are dependent on angiogenesis, the role of angiogenic stimuli in the enhanced CD44 expression was investigated. We found that basic fibroblast growth factor (bFGF ) and vascular endothelial growth factor were able to efficiently upregulate CD44 expression on cultured human EC. The upregulation reached maximal levels after treatment for 3 days with 10 ng/mL bFGF. The physiological impact of this upregulation was shown by the enhanced binding of EC to hyaluronate after pretreatment with bFGF. In a next set of studies that were designed to unravel the regulation of CD44 expression on EC we concluded that CD44 is an activation antigen on human EC since (1) human umbilical vein derived endothelial cells, which in vivo do not express CD44, begin to express CD44 when plated and cultured, (2) CD44 expression is enhanced after subculture of confluent cultures, (3) CD44 is predominantly expressed on the BrdU incorporating subset of cultured EC. The specific expression of CD44 on activated and tumor EC prompted us to study the usefulness of CD44 as an endothelial target for therapy with immunotoxins. In vitro experiments showed that EC are efficiently killed after targeting immunotoxin to CD44.

Antigen expression of metastasizing and non-metastasizing human melanoma cells xenografted into nude mice

In order to study differences in antigen expression related to the different stages of the process of metastasis of human melanoma cell lines, we determined the expression pattern of a series of well-characterized genes in a set of human melanoma cell lines with different metastatic behavior in nude mice. This set included non-metastatic (IF6, 530), sporadically metastatic (M14, Mel 57), and frequently metastatic (BLM, MV3) cell lines after subcutaneous inoculation. To study the phenotype of these cell lines both the cultured cells and representative samples of local tumors at the inoculation site and their metastases in the lungs were immunostained with a panel of monoclonal antibodies directed against melanocytic differentiation or progression antigens. Although most cell lines (IF6, 530, M14 and Mel 57) showed HLA-DR expression in vitro, these antigens were lacking in all xenografted lesions studied with exception of the 530 cell line. 530 Xenografts, however, showed a dramatic down-regulation of HLA-DR compared with the cell line in vitro. The same phenomenon was seen with respect to ICAM-1 expression. The expression of all other antigens studied in xenografts, both in subcutaneous tumors and in lung lesions, was in general comparable to that in the melanoma cell lines in vitro, with exception of the 530 cell line. In all melanoma cell lines except 530 the degree of intra- and interlesional heterogeneity regarding the expression of all antigens studied was limited. Remarkably, comparison of the immunophenotype of the frequently metastasizing (BLM, MV3) and the sporadically (M14, Mel 57) or non-metastasizing (IF6, 530) cell lines showed that the two frequently metastasizing cell lines had marked expression of the progression antigens VLA-2 and epidermal growth factor receptor, and lack of expression of the differentiation antigen NKI-beteb. These findings warrant further studies on the role of these antigens in the process of metastasis of human melanoma cells in nude mice.

Functional analysis of HLA-DR-expressing keratinocytes from tuberculin reactive skin

We examined the functional roles of HLA-DR+ keratinocytes which were induced in vivo from tuberculin reactive skin. At 4 days after intradermal PPD injection, about 80% of keratinocytes obtained from the tuberculin reactive area expressed DR antigens. In 14 of 18 individuals examined, PPD-pulsed DR+ keratinocyte fraction induced autologous T-cell proliferation. The proliferative response was PPD-dependent, antigen specific; it depended upon DR expression by the keratinocyte fraction, because it did not occur in the presence of the PPD-nonpulsed DR+ keratinocyte fraction and was completely blocked by mouse monoclonal antibody to HLA-DR. However, the antigen-presenting capacity of the DR+ keratinocyte fraction appeared to be less than that of monocytes or the DR+ epidermal cell fraction. The DR+ keratinocyte fraction was also able to stimulate allogeneic T-cell DNA synthesis, but the DR- keratinocyte fraction could not. The possible influences of contaminant Langerhans cells and mononuclear cells in the DR+ keratinocyte fraction were considered to be unlikely. These results suggest that DR+ keratinocytes, which are induced in vivo, can both present the antigen to autologous T cells and stimulate allogeneic T cells.

Class II antigens of the major histocompatibility complex are increased in lungs of bleomycin-treated rats

The expression of class II molecules (Ia) of the major histocompatibility complex by isolated alveolar macrophages (AM) and alveolar type II cells from the lungs of rats with bleomycin-induced pulmonary fibrosis was examined. The percentage of Ia-positive AM and type II cells from rats treated with bleomycin as detected by flow cytometry was increased three times and two times, respectively, over the values obtained from control rats. The relative density of Ia expression, determined with a radioimmunoassay technique, showed a 50% increase in Ia density on AM and a 35% increase on type II cells. Recombinant interferon-gamma increased the expression of Ia on type II cells in vitro by 35% to the level obtained on type II cells in bleomycin-induced lung disease. We conclude that the increase of Ia expression on cells of the immune system and on pulmonary epithelial cells may have an important role in the initiation and/or amplification of inflammatory reactions in the lung and may contribute to the development of pulmonary fibrosis.

Class II (HLA-DR, -DP, and -DO) antigens on intestinal epithelia in ulcerative colitis, Crohn's disease, colorectal cancer and normal small intestine

Class II antigens in involved colonic epithelia of ulcerative colitis (UC), Crohn's disease (CD), colorectal cancer, and epithelia of normal small intestine were investigated using an immunoperoxidase method. Ten normal colonic mucosa served as normal controls. Ten specimens were studied for each group. Normal colonic epithelia did not express class II antigens. In colonic diseases; (1) with regard to the frequency and extent of class II antigens on epithelia. HLA-DR antigens were the most highly and greatly expressed, followed by HLA-DP and then HLA-DQ antigens. (2) The extent of HLA-DR and -DP, but not HLA-DQ, expression on epithelia of UC and colorectal cancer seemed to be positively correlated with the degree of mononuclear cell infiltration in the lesion. (3) The extent of class II antigen expression on colonic epithelia in CD was not related to the degree of mononuclear cell infiltration in the lesion. (4) The extent of HLA-DR and -DP expression on epithelia of colorectal cancer seemed to be positively correlated with increasing undifferentiation. In the normal small intestine, where HLA-DR antigens were physiologically expressed on epithelia. HLA-DQ antigens were not expressed. The heterogeneity among colonic diseases, and between the physiological and pathological status, may reflect differences in immunoregulation.

Spontaneous and in vitro activation of synovial fluid and peripheral blood lymphocytes in rheumatoid arthritis

Peripheral blood (PB) and synovial fluid (SF) were compared in parallel samples in rheumatoid arthritis (RA). The kinetics of in vitro T-cell activation was assessed in phytohemagglutinin (PHA) stimulated PB or SF mononuclear cell cultures on days 0, 1, 3 and 5. The early lymphocyte activation as assessed by interleukin-2 receptor expression was faster in SF than in PB cell cultures. In particular, IFN-gamma secretion was higher in SF than in PB cell cultures (p less than 0.01). Accordingly, lymphocyte major histocompatibility complex (MHC) locus II antigen expression was higher in SF than in PB cell cultures (53 +/- 7% vs. 21 +/- 5%; p less than 0.01). Our results suggest that lymphocytes, which are particularly effective producers of IFN-gamma when stimulated in vitro are sequestered in the diseased joints in RA.

MHC class II antigen expression in human vascular smooth muscle cells is induced by interferon-gamma and modulated by tumour necrosis factor and lymphotoxin

Arterial smooth muscle cells (SMC) express major histocompatibility complex (MHC) class II antigens in experimental vasculitis and in the human atherosclerotic plaque. We have therefore studied the regulation of expression of MHC antigens in cultured human arterial SMC, using immunofluorescence, radioimmunoprecipitation and a quantitative cell-surface immunoradiometric assay. SMC expressed class I, but not class II, antigens on their cell surfaces under basal conditions. Treatment of SMC with recombinant or natural interferon-gamma (IFN-gamma) induced expression of class II antigens in the following order of intensity, DR greater than DP greater than DQ. HLA-DR protein in SMC showed the same MW as that synthesized by B-lymphoblastoid cells. Antibodies to IFN-gamma blocked all HLA-DR-inducing activity in mixed leucocyte reaction (MLR) supernatants and PHA-stimulated peripheral blood mononuclear cell (PBMC)-conditioned media, indicating that IFN-gamma is the only lymphokine secreted under these conditions that is capable of de novo induction of HLA-DR expression in SMC. Treatment of SMC with recombinant human tumour necrosis factor-alpha (TNF) or lymphotoxin (LT) did not per se induce class II antigen expression. However, both TNF and LT substantially enhanced IFN-gamma-induced expression of HLA-DQ while decreasing that of HLA-DP. TNF, but not LT, increased HLA-DR expression. Also, in dermal fibroblasts, IFN-gamma-induced HLA-DP expression was significantly inhibited in the presence of TNF. These data demonstrate that TNF and LT differentially modulate IFN-gamma-induced MHC antigen expression in mesenchymal cells. The fact that SMC can express MHC class II antigens suggests that this cell type may serve as an accessory cell in the initiation of the immune response.

Increased expression of HLA-DQ antigens by interstitial cells and endothelium in the synovial membrane of rheumatoid arthritis patients compared with reactive arthritis patients

We investigated cellular phenotypes and expression of class II major histocompatibility complex antigens on endothelium and cellular infiltrates in synovium from patients with rheumatoid arthritis (RA) or reactive arthritis, using an indirect immunoperoxidase technique. The RA specimens showed synovial lining layer hypertrophy and several focal accumulations of lymphocytes, both of which were absent in the reactive arthritis synovium. The percentage of cells expressing monocyte/macrophage markers was significantly higher in RA specimens. The percentages of cells expressing B and T cell markers were similar in both diseases. There was no significant difference in the expression of HLA-DR or DP by endothelium in the 2 diseases, but a marked increase in expression of HLA-DQ by endothelium was observed in the RA synovium versus that from patients with reactive arthritis. This overexpression of HLA-DQ was also seen in the interstitial cells of RA patients compared with reactive arthritis patients. In the reactive arthritis synovium, a significant population of cells (30%) was noted to be HLA-DR positive, and negative for macrophage and lymphocyte markers. Some of these cells had a dendritic morphology. The coexpression of HLA-DQ and HLA-DR may play an important role in antigen presentation and disease chronicity in RA.

Modulation of macrophage Ia expression by lipopolysaccharide: stem cell requirements, accessory lymphocyte involvement, and IA-inducing factor production

The mechanism of induction of murine macrophage Ia expression by lipopolysaccharide (LPS) was studied. Intraperitoneal injection of 1 microgram of LPS resulted in a 3- to 10-fold increase in the number of IA-positive peritoneal macrophages (flow cytometry and immunofluorescence and a 6-to 16-fold increase by radioimmunoassay. The isolated lipid A moiety of LPS was a potent inducer of macrophage Ia expression. Ia induction required a functional myelopoietic system as indicated by the finding that the response to LPS was eliminated in irradiated (900 rads) mice and reinstated by reconstitution with bone marrow cells. Comparison of LPS-induced Ia expression in normal and LPS-primed mice revealed a faster secondary response to LPS. The memory response could be adoptively transferred to normal mice with nonadherent spleen cells prepared 60 days after LPS injection. Spleen cells prepared 5 days after LPS injection caused Ia induction in LPS-nonresponder mice; such induction was not observed in irradiated (900 rads) recipients. The cell responsible for this phenomenon was identified as a Thy-1+, immunoglobulin-negative nonadherent cell. The biosynthesis and expression of Ia were not increased by direct exposure of macrophages to LPS in vitro. Small amounts of LPS inhibited Ia induction by gamma interferon. LPS showed positive regulatory effects on Ia expression by delaying the loss of Ia expression on cultured macrophages and by stimulating the production of Ia-inducing factors. Supernatants from cultured spleen cells stimulated with LPS in vitro contained antiviral and Ia-inducing activity that was acid labile, indicating that the active factor is gamma interferon. We conclude that induction of Ia expression by LPS in vivo is a bone-marrow-dependent, radiation-sensitive process which involves the stimulation of a gamma interferon-producing accessory lymphocyte and a delay in Ia turnover.

Nickel antigen induces IL-2 secretion and IL-2 receptor expression mainly on CD4+ T cells, but no measurable gamma interferon secretion in peripheral blood mononuclear cell cultures in delayed type hypersensitivity to nickel

Nickel sulphate antigen-induced peripheral blood lymphocyte activation in vitro was characterized by lymphokine measurement (IL-2, IFN-gamma) and phenotyping of the IL-2 responsive cells. Mononuclear cells from nickel-sensitive patients synthesized more DNA, produced more IL-2 and had more IL-2 receptor positive cells in response to nickel than did those of the control subjects. On the other hand no IFN-gamma was detectable in the nickel supernatants, while PPD, used as the control antigen, induced pronounced quantities of IFN-gamma with an equal amount of DNA synthesis. The increase in IL-2 receptor positive cells was due to activation of CD4+ (helper/inducer) T cells. T cells with HLA-DR antigen surface markers were more numerous on each day of culture than cells with IL-2 receptors. These two activation markers were co-expressed on the same cells only to a certain extent, thus perhaps reflecting different types or phases of activation. In conclusion, nickel-induced peripheral blood mononuclear cell activation in vitro differs from microbial antigen-induced activation with respect to its modest or non-existent IFN-gamma response.

Oral lesions of lupus erythematosus patients in relation to other chronic inflammatory oral diseases: an immunologic study

The nature and distribution of mononuclear cells in non-ulcerated oral lesions of discoid (DLE) and systemic lupus erythematosus (SLE), were investigated and compared to other chronic inflammatory oral diseases (lichen planus (LP), contact lesion (CL), unspecified inflammation (UI), geographic tongue (GT), and leukoplakia (LK). For this purpose an immunoperoxidase technique based on staining with monoclonal antibodies was employed. In most LE specimens examined infiltrating cells consisted predominantly of a mixture of T cells (Leu 3a+ and Leu 2a+) that were distributed in the lamina propria, the submucosa, and occasionally also in the epithelium. In general, only few B cells were detected while macrophages were more frequent. In all LE specimens examined beta 2-microglobulin expression was observed on a large proportion of cells including infiltrating mononuclear cells as well as resident keratinocytes. In addition, most infiltrating cells displayed MHC Class II antigens according to a pattern HLA-DR greater than DQ greater than DP. Interestingly, expression of Class II antigens was also observed on epithelial keratinocytes but was restricted to HLA-DR and -DP gene products (DR much greater than DP). HLA-DQ expression was never observed on keratinocytes. In most LE specimens studied a small proportion (less than 5%) of inflammatory cells had detectable interleukin-2 receptors (IL-2R) and/or transferrin receptors (transf-R). However, expression of transf-R was also observed on basal epithelial cells, being more pronounced in DLE than in SLE lesions. The above staining patterns observed in LE lesions, when compared to other chronic inflammatory oral lesions, did not disclose any striking differences that could support the specific diagnosis of LE. However, the findings of Class I and II MHC gene products on oral keratinocytes suggest an important accessory role for these cells in directing the migration of activated lymphoid cells in the epithelium in chronic inflammatory lesions of the oral mucosa.

Expression of HLA-DR antigens in inflammatory bowel disease mucosa: role of intestinal lamina propria mononuclear cell-derived interferon gamma

The expression of HLA-DR antigens on the surface of immune cells is crucial for appropriate antigen presentation and a normal immune response. In the intestinal mucosa involved by Crohn's disease and ulcerative colitis the expression of HLA-DR antigens is increased in both immune and nonimmune cells, a phenomenon probably mediated by soluble factors, such as interferon gamma, produced by locally activated mononuclear cells. This study investigated the production of interferon gamma by inflammatory bowel disease and control intestinal lamina propria mononuclear cells, and the ability of this endogenously produced lymphokine to induce expression of HLA-DR antigens on the monocytic cell lines U937 and ML3. After in vitro stimulation with interleukin 2 or phytohemagglutinin, but not spontaneously, lamina propria mononuclear cells produced variable amounts of interferon gamma, and their culture supernatants could induce de novo expression of HLA-DR antigens on the monocytic indicator cells. When the mononuclear cells were derived from inflammatory bowel disease mucosa, both the amount of interferon gamma present in the supernatants and the number of HLA-DR-positive cells induced by these supernatants were decreased as compared to controls. These results suggest that, in inflammatory bowel disease, interferon gamma may not be the only mediator of HLA-DR induction in the gut and that other soluble factors or agents, alone or interacting with interferon gamma, may also be responsible for this event, resulting in the enhanced HLA-DR antigen expression observed in the inflamed intestinal mucosa.

Interferon gamma production by human intestinal mucosal mononuclear cells. Decreased levels in inflammatory bowel disease

Immune (gamma) interferon is a substance produced by immunologically activated mononuclear cells. Besides its antiviral activity, interferon gamma has a crucial role in immunoregulation, by acting directly upon lymphocytes and monocytes, and interacting with other soluble mediators of the immune response. Studies of the interferons system in inflammatory bowel disease have been limited, and little information is available on the generation of interferon during immunological events occurring in the human gut. To investigate the capacity of intestinal mucosal mononuclear cells to produce interferon gamma, lamina proprial mononuclear cells, isolated from Crohn's disease, ulcerative colitis, and control patients, were incubated with interleukin 2 or phytohemagglutinin, and the amounts of interferon gamma present in the culture supernatants were measured by a virus cytopathic effect inhibition assay. Under identical stimulatory conditions, culture supernatants of cells derived from actively involved mucosa of inflammatory bowel disease specimens contained two- to fivefold less interferon gamma than those of cells from control tissue. However, the amount of interferon gamma present in supernatants of cells from uninvolved inflammatory bowel disease mucosa was similar to that found in control supernatants. These results indicate that, in patients with active Crohn's disease and ulcerative colitis, mononuclear cells produce decreased amounts of interferon gamma in the intestinal mucosa. The exact significance of these findings is unclear, but because of the importance of interferon gamma in a variety of cell-mediated immune phenomena, its impaired availability might be relevant to the pathogenesis of inflammatory bowel disease.

DNA content and MHC class II antigen expression in malignant melanoma: clinical course

To assess the clinical value of two comparatively new properties (DNA content and MHC class II antigen expression (HLA-DR, DP, DQ) of melanoma cells) which have been independently reported to reflect the outlook for patients with malignant melanoma, we investigated retrospectively 50 stage I nodular melanomas in two comparably homogeneous groups of 23 and 27 patients, the course of whose disease differed at five years. Flow cytometry and immunohistology were used on paraffin wax embedded archival material for the analysis of DNA ploidy and detection of class II antigens, respectively. A close association was found between class II antigen expression, detected by monoclonal antibody CR3/43 (antimonomorphic DR, DP, DQ) present in 23 of 50 (46%) melanomas and unfavourable clinical course (p less than 0.005, by log rank test), but no such association was found for DNA ploidy. It is suggested that immunohistology for MHC class II antigen expression may help to predict the behaviour of nodular melanomas whereas the prognostic value of DNA ploidy is more limited. The finding that class II positive cells are found predominantly in melanomas with a substantially increased risk of metastases has implications both for concepts of tumour heterogeneity and host immunity.

Effect of cytokines and growth factors on the expression of elastase activity by human synoviocytes, dermal fibroblasts and rabbit articular chondrocytes

Human synoviocytes, rabbit articular chondrocytes and human skin fibroblasts in culture were examined for their ability to express elastase activity. Latent enzyme activity degrading insoluble elastin was detected in the culture media of the three cell types and was completely abolished by metal chelating agents. Triton X-100 cell extracts were found to degrade a synthetic elastase substrate, N Succinyl-(Ala)3p-nitroanilide (SANA). The SANA-degrading activity of cell extracts could be attributed to a metalloprotease for fibroblasts and synoviocytes (100%) and to a metalloprotease associated with a cysteine protease for chondrocytes (70 and 30% respectively). This SANA-degrading activity was partly due to the combined action of an endo and an exopeptidase. Tumor Necrosis Factor-alpha (TNF-alpha) and Interferon-gamma (IFN-gamma) significantly enhanced the elastin degrading activity present in the culture media of both synoviocytes and chondrocytes. Interleukin-1 beta significantly increased the secretion of elastase by chondrocytes. By contrast, Transforming Growth Factor-beta (TGF-beta) reduced by 80 per cent the secretion of elastinolytic activity by chondrocytes but had not effect on other cell types.

Short-term lymphokine stimulation of human peripheral blood mononuclear cells generates cytolytic activity against endothelial cells: involvement of natural killer cells

We previously reported that incubation of human peripheral blood mononuclear cells (PBMC) for 5 days with T-cell growth factor (TCGF) resulted in lymphokine-activated killer activity against endothelial cells (EC). In this paper we report on the effects of short-term incubation of PBMC with lymphokines. We show that incubation of PBMC with lymphokines during an 18-hr period is sufficient to generate a strong cytolytic response against EC. The cytolytic capacity of the effector cells was directly dependent on the dose of lymphokine added during the induction phase. When PBMC were separated into adherent and non-adherent cells, the non-adherent fraction could be induced to lytic activity against EC, whereas the adherent cells could not. When PBMC were separated, using 2-amino-ethylisothiouronium bromide hydrobromide-treated sheep red blood cells (AET-SRBC), into T- and non-T-cell fractions, the latter fraction could be induced to lyse EC. TCGF-induced cell-mediated EC lysis could not be inhibited using anti-T3 nor anti-LFA-1 antibodies. Lysis of EC by TCGF-stimulated effector cells was strongly inhibited by the addition of unlabelled K562 target cells, whereas cold OKT3 hybridoma cells did not exert such an effect.

IN CONCLUSION

the kinetics of the induction of lytic activity against EC, as well as the cell separation experiments, suggest that short-term-activated NK cells may lyse EC. This hypothesis was confirmed using monoclonal antibody and cold target cell analysis.

Autocrine secretion of tumor necrosis factor under the influence of interferon-gamma amplifies HLA-DR gene induction in human monocytes

Recombinant interferon-gamma (IFN-gamma) induced HLA-DR gene expression in both U937 and THP-1 human monocytic cell lines, although the former was only very weakly inducible. Combination of recombinant tumor necrosis factor (TNF) and IFN-gamma resulted in a synergistic enhancement of DR mRNA and protein induction in both cell lines. TNF alone increased the constitutive expression of the DR gene in THP-1 cells. In the HLA class II-negative U937 cells, TNF used alone was not able to induce DR gene expression. Such a negative result was not due to a lack of TNF receptor expression in U937 cells, since TNF clearly induced HLA class I and TNF gene expression in this cell line. THP-1, but not U937, cells secreted TNF under the influence of IFN-gamma. Neutralization of TNF by a specific antibody decreased IFN-gamma-induced DR antigen expression in THP-1 cultures. These observations indicate that TNF is not able to directly induce DR gene expression, but rather amplifies ongoing expression of this gene, whether constitutive or induced by IFN-gamma. In the two cell lines tested, the level of DR inducibility under the influence of IFN-gamma used alone depended on a different inducibility of TNF secretion by IFN-gamma. Altogether, our observations indicate that TNF, whether exogenous or endogenously produced under the influence of IFN-gamma, amplifies DR gene expression in monocytes, a phenomenon that may provide to such antigen-presenting cells a selective sensitivity to the DR-inducing effects of IFN-gamma.

Cytokines amplify the function of accessory cells

Accessory cells have two broad functions at the onset of T cell-mediated immunity. One is the "presentation" of antigen in association with MHC products. The other is a "sensitization" function which is thought to require IL-1 and leads to the development of lymphoblasts that secrete lymphokines and respond to T cell growth factors. This review summarizes evidence, much of it recent, that specific cytokines upregulate both the presentation and sensitization functions of accessory cells. Lymphokines, particularly IFN-gamma, upregulate class II MHC products on macrophages and many non-leukocytes, but not dendritic cells. The enhanced levels of class II improve presentation to T lymphoblasts, but not the sensitization of unprimed and memory T cells. Dendritic cells in lymph and lymphoid organs are active accessory cells for primary responses without any supplementation by exogenous cytokines. IL-1, while not a product of dendritic cells, further amplifies their function several fold. In thymus, IL-1 has a second effect, including the formation of Ia+ thymic dendritic cells from Ia- precursors. Granulocyte-macrophage colony stimulating factor (GM-CSF) is an important cytokine for epidermal Langerhans cells, which are immature dendritic cells. GM-CSF maintains viability in culture, and enhances the sensitization function for primary responses 10-20 fold. Why does the immune system regulate expression of Ia on many cell types, as well as dendritic cell function? In the discussion, it is proposed that the local modification of accessory cells by cytokines helps to reduce anti-self or autoreactive T cell responses, and to enhance the retention of sensitized T cells at sites of antigen deposition.

Cytokines in chronic inflammatory synovitis

Cytokines likely play a role in the pathogenesis of rheumatoid arthritis and other chronic inflammatory arthritidies. Recent studies on the cytokine profile of inflammatory synovitis have provided insight into the mechanisms of cellular activation in the inflamed joint. Although gamma interferon has been proposed as a major macrophage activating factor and inducer of class II major histocompatibility antigens in the joint, studies using sensitive and specific immunoassays have shown that the concentration of this lymphokine in synovial fluid is probably not sufficient to account for the high level of HLA-DR expression on Type A synoviocytes and macrophages in the joint. In contrast, GM-CSF has recently been identified in synovial effusions of patients with rheumatoid arthritis and is produced by synovial tissue cells in vitro. Like gamma interferon, GM-CSF is a known macrophage activating factor and induces HLA-DR on cells of macrophage lineage. Furthermore, supernatants of cultured synovial tissue cells contain an HLA-DR inducing factor that is neutralized by specific antibodies to GM-CSF but not by antibodies to gamma interferon. These data suggest that GM-CSF plays a significant role in macrophage activation in the synovium.

Comparison of gamma-interferon and alloantigen-induced T cell factors in the induction of MHC class II antigen expression and in the modulation of the immunogenicity of lymphocyte-free rat bone marrow

In a rat model, we compared the effects of various soluble products released by T cells, such as the unspecifically acting gamma-interferon or the newly detected alloantigen-induced factors that specifically act on nonlymphoid, hemopoietic bone marrow cells. We found two types of reactivity patterns with regard to the induction of MHC class II antigen expression on these cells. The very same patterns could be demonstrated when we investigated the modulation of their stimulatory capacity, i.e., their immunogenicity in a T proliferation assay. These findings are discussed in relation to the increasing incidence of immunologically mediated graft rejections in clinical bone marrow transplantation following T cell purging.

Immunohistological observations in rat kidney allografts after local steroid administration

In this report we investigated local regulatory mechanisms in graft rejection and their response to local immunosuppressive therapy. For this purpose local immunosuppression was induced in rat kidney allografts by intrarenal infusion of prednisolone. Intrarenal drug delivery resulted in high drug levels within the graft and low systemic drug levels. Systemic drug levels were by themselves not sufficiently immunosuppressive to induce graft survival, and local prednisolone levels within the graft proved to be responsible for prolongation of graft survival. During intrarenal drug delivery, systemic responsiveness to the renal allograft proved normal, since intrarenally treated grafts were infiltrated by MHC class II-positive host cells and, except for a somewhat lower percentage of macrophages, cellular infiltration in intrarenal treated grafts was comparable to untreated grafts. However, T cells and macrophages present in intrarenally treated grafts were not able to destroy the grafted tissue. Local immunosuppressive therapy resulted in inhibition of IL-2-R expression, absence of IFN-gamma, and prevention of MHC class II induction on grafted tissue. These observations strongly indicate the presence of local regulatory mechanisms in graft rejection. The experimental model described can be used for further analysis of these intragraft events. Moreover, the results demonstrate that local immunosuppressive therapy can contribute to effective inhibition of cellular immune response in graft rejection.

Gamma interferon-mediated increase in the number of Ia-bearing macrophages during infection with Listeria monocytogenes

The role of gamma interferon (IFN-gamma) in an increase in Ia-bearing macrophages during Listeria monocytogenes infection was studied. The peritoneal macrophages from L. monocytogenes-infected mice contained a high proportion of Ia. Intraperitoneal injection of the supernatant from a culture of spleen cells from L. monocytogenes-infected mice induced Ia-rich exudates in normal mice. The Ia-inducing activity in the culture supernatant was abrogated by the pretreatment of spleen cells with anti-Thy-1.2 antibody plus complement. Immunoadsorption of the culture supernatant with anti-recombinant IFN-gamma antibody and protein A-Sepharose CL-4B completely abrogated its Ia-inducing activity. These results suggested that an increase in Ia-bearing macrophages during L. monocytogenes infection was attributable to T-cell-derived IFN-gamma.

Endothelial cell lysis induced by lymphokine-activated human peripheral blood mononuclear cells

In vitro exposure of human peripheral blood mononuclear cells (PBMC) to interleukin 2 results in the generation of lymphokine-activated killer (LAK) cells. Such LAK cells exhibit cytotoxicity against a spectrum of tumor target cell lines whereas they apparently do not affect normal tissues. In this report we show that PBMC that have been activated with T cell growth factor lyse trypsinized human umbilical cord venous endothelial cells as well as endothelial cell monolayers in a dose-dependent manner. Microscopic analysis showed that during the 4-h incubation period cell clumps containing detached endothelial cells and LAK cells were formed. When these clumps were evaluated with trypan blue the endothelial cells stained positive whereas LAK cells excluded the dye. No lysis occurred when fresh PBMC were added to target endothelial cells. The endothelial cell kill could not be blocked with an anti-LFA-1 antibody nor with intact OKT3 or F(ab')2 fragments of WT32. We conclude that lymphokine-activated PBMC exhibit cell-mediated endothelial cell detachment and lysis.

MHC antigen expression in sequential biopsies from cardiac transplant patients--correlation with rejection

Class I induction on the myocardium of transplanted heart was investigated with regard to its temporal relationship to rejection episodes, how it is affected by anti-rejection therapy and whether it is dependent upon the presence of a T cell infiltrate in the biopsy. Sequential cardiac biopsies (total 114) from 11 patients from the time of transplant to 1 year after transplant were studied using immunocytochemical techniques. The effect of different immunosuppressive regimens on MHC antigen expression was also studied. All the biopsies diagnosed as showing rejection for the first time showed induction of Class 1 on the myocardium with 79% during subsequent rejection episodes. Class I induction was associated with a leucocyte infiltrate, not always containing T cells, and disappeared in 47% of biopsies taken 3-4 weeks after treatment with steroids and/or ATG. Increased expression of Class II, in particular DQ antigens on interstitial structures, paralleled Class 1 induction. MHC antigen expression returned to normal in 8/9 patients, at 1 year after transplant. Different immunosuppressive regimens affected the number of biopsies showing Class 1 induction on the myocardium. Our results suggest that in clinical heart transplantation class I induction is related to the rejection process.

A simple in vitro technique for studies on induction of class II transplantation antigens on keratinocytes

A new technique is described for evaluation of the induction and kinetics of class II transplantation antigens on keratinocytes. By culturing small rat or human skin specimens for 2-5 days in media containing gamma-interferon, class II antigens were detected on keratinocytes by immunohistochemistry. This technique is rapid and technically simple compared to keratinocyte cultures and raises the possibility of studying other cells in the skin.

Peripheral blood and synovial fluid monocyte activation in inflammatory arthritis. II. Low levels of synovial fluid and synovial tissue interferon suggest that gamma-interferon is not the primary macrophage activating factor

Because synovial fluid monocytes (SFM) in patients with inflammatory arthritis bear an activated phenotype (i.e., high expression of HLA-DR and low expression of the monocyte differentiation antigen Mo2), we assessed the role of gamma-interferon (gamma-IFN) in the activation of these cells. Sensitive and specific radioimmunoassays detected only 0.40 +/- 0.20 units/ml of gamma-IFN in the SF of patients with rheumatoid arthritis (RA) and 0.61 +/- 0.67 units/ml of gamma-IFN in the SF of patients with other forms of chronic inflammatory arthritis. There was no detectable alpha-IFN in any SF studied by radioimmunoassay. Bioassays failed to detect nonimmunoreactive IFN. Synovial tissue (ST) explants produced very little gamma-IFN (0.14 +/- 0.091 units/ml), and production was not increased by the presence of indomethacin in the cultures or by removal of adherent cells. However, gamma-IFN was produced if ST was cultivated in the presence of phytohemagglutinin. In SF and ST supernatants, gamma-IFN-mediated induction of HLA-DR on monocytes was inhibited, even though the amount of immunoreactive IFN was not affected. Prostaglandin E2 was shown to be one possible inhibitor. We demonstrated that a factor that induces HLA-DR on some individuals' peripheral blood monocytes, and cannot be neutralized by monoclonal anti-gamma-IFN antibody, is present in SF and ST supernatants. These data suggest that activation of SFM may occur by mechanisms other than gamma-IFN.

Peripheral blood and synovial fluid monocyte activation in inflammatory arthritis. I. A cytofluorographic study of monocyte differentiation antigens and class II antigens and their regulation by gamma-interferon

Recent study of the expression of monocyte differentiation antigens (MAg) and HLA-DR on peripheral blood monocytes (PBM) has led to the recognition of resting and activated monocyte phenotypes. The former is identified by the expression of large amounts of MAg (i.e., Mo2 and 63D3) and small amounts of HLA-DR, while the latter is identified by the reverse. We studied the phenotypes of PBM and synovial fluid monocytes (SFM) of patients with chronic inflammatory arthritis and found that PBM were primarily resting and SFM were usually activated. In addition, we measured the degree of modulation of MAg and HLA-DR by gamma-interferon (gamma-IFN). Patient PBM reacted the same as PBM from normal individuals (i.e., MAg decreased and HLA-DR increased after exposure to gamma-IFN). However, in patient SFM, HLA-DR did not increase with exposure to gamma-IFN because expression was already maximal. Interestingly, MAg could still be down-regulated on gamma-IFN-treated SFM, even when expression began at a very low level (i.e., activated phenotype). This independent regulation of MAg and HLA-DR suggests that macrophage activating factors other than gamma-IFN may be responsible, in part, for the activated phenotypes observed.