Loss of suppressor T-cells in active inflammatory bowel disease

CD8+ T-Cell Deficiency, Epstein-Barr Virus Infection, Vitamin D Deficiency, and Steps to Autoimmunity: A Unifying Hypothesis

CD8+ T-cell deficiency is a feature of many chronic autoimmune diseases, including multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus, Sjögren's syndrome, systemic sclerosis, dermatomyositis, primary biliary cirrhosis, primary sclerosing cholangitis, ulcerative colitis, Crohn's disease, psoriasis, vitiligo, bullous pemphigoid, alopecia areata, idiopathic dilated cardiomyopathy, type 1 diabetes mellitus, Graves' disease, Hashimoto's thyroiditis, myasthenia gravis, IgA nephropathy, membranous nephropathy, and pernicious anaemia. It also occurs in healthy blood relatives of patients with autoimmune diseases, suggesting it is genetically determined. Here it is proposed that this CD8+ T-cell deficiency underlies the development of chronic autoimmune diseases by impairing CD8+ T-cell control of Epstein-Barr virus (EBV) infection, with the result that EBV-infected autoreactive B cells accumulate in the target organ where they produce pathogenic autoantibodies and provide costimulatory survival signals to autoreactive T cells which would otherwise die in the target organ by activation-induced apoptosis. Autoimmunity is postulated to evolve in the following steps: (1) CD8+ T-cell deficiency, (2) primary EBV infection, (3) decreased CD8+ T-cell control of EBV, (4) increased EBV load and increased anti-EBV antibodies, (5) EBV infection in the target organ, (6) clonal expansion of EBV-infected autoreactive B cells in the target organ, (7) infiltration of autoreactive T cells into the target organ, and (8) development of ectopic lymphoid follicles in the target organ. It is also proposed that deprivation of sunlight and vitamin D at higher latitudes facilitates the development of autoimmune diseases by aggravating the CD8+ T-cell deficiency and thereby further impairing control of EBV. The hypothesis makes predictions which can be tested, including the prevention and successful treatment of chronic autoimmune diseases by controlling EBV infection.

Deficit of gammadelta T lymphocytes in the peripheral blood of patients with Crohn's disease

BACKGROUND

Gammadelta T lymphocytes are an important component of innate immunity. Previous studies have shown their role in the development of Crohn's-like colitis in mice.

AIMS

The aim of this study was to measure the γδ T lymphocyte levels in Crohn's disease (CD) patients.

METHODS

A prospective study of 40 patients with CD compared with 40 healthy subjects (control group) matched by age and sex was undertaken. Lennard-Jones criteria were used for the diagnosis of CD. Disease activity was measured with the Crohn's disease activity index (CDAI). New patients, patients in remission, and patients with active disease were evaluated. Lymphocytic populations of CD3+, CD4+, CD8+, CD56+, CD19+, and αβ and γδ subsets were measured in the peripheral blood of all participants.

RESULTS

The levels of CD3+, CD4+, CD8+, and CD19+ lymphocytes were decreased in CD patients compared with the control group (P = 0.002, 0.049, 0.003, and 0.023, respectively). Although both γδ and αβ T lymphocytes were lower in patients with CD, γδ T subsets showed the lowest levels in CD patients (mean 0.0259 × 10(9)/l) versus healthy controls (mean 0.0769 × 10(9)/l), P < 0.001. In particular, γδ CD8+ T subsets (mean 0.0068 × 10(9)/l) had the largest difference compared to the control group (mean 0.0199 × 10(9)/l), P = 0.008.

CONCLUSIONS

There is a decrease in the global lymphocyte population in the peripheral blood of patients with CD compared to healthy controls. This decrease is more evident in γδ T lymphocytes, especially γδ CD8+ T subsets. Our conclusion is that these results support the theory that a complex alteration of immune responses that affects the total numbers and function of γδ T cells is present in CD.

Treatment of Crohn's disease by lymphocyte apheresis: a randomized controlled trial. Groupe d'Etudes Thérapeutiques des Affections Inflammatoires Digestives

BACKGROUND/AIMS

Several uncontrolled trials suggest that lymphapheresis improves the clinical course of patients with Crohn's disease; this study was designed to assess the efficacy of lymphapheresis in preventing early relapses of Crohn's disease in patients in clinical remission after steroid treatment for an acute attack.

METHODS

Twenty-eight patients in clinical remission at the end of 3-7 weeks of steroid therapy were included in this randomized multicenter prospective trial. Before starting steroid tapering, patients were randomly assigned either to the lymphapheresis group (9 procedures within 4-5 weeks) or to the control group. The primary judgement criterion was the cumulated recurrence rate after steroid discontinuation.

RESULTS

All the patients treated by lymphapheresis (12 of 12) were successfully withdrawn from prednisolone and only 10 of 15 in the control group (NS). At the end of the 18-month follow-up period, the cumulated relapse rate was 83% in the lymphapheresis group and 62% in the control group.

CONCLUSIONS

Although there was a trend towards a diminished incidence of corticosteroid dependence, lymphapheresis did not prevent the occurrence of early relapses.

Flow cytometric analysis of peripheral blood lymphocytes in ulcerative colitis and Crohn's disease

Using two colour immunofluorescence with fluorescein isothiocyanate and phycoerythrin labelled monoclonal antibodies, multi-parameter flow cytometry was used to examine the antigenic characteristics of peripheral blood lymphocytes in whole blood of patients with ulcerative colitis and Crohn's disease who were not taking immunosuppressive drugs. The numbers of CD4+ and CD8+ lymphocytes in patients with ulcerative colitis and Crohn's disease remained unchanged so that the CD4/CD8 ratio was the same as that of normal control subjects. In Crohn's disease there were many activated T cells (CD3+, CD25+). Although natural killer cells in active Crohn's disease were lower than in normal control subjects, cytotoxic T lymphocytes, as defined by CD3+, CD16+, did not differ in patients with inflammatory bowel disease compared with normal control subjects. For B cell subsets, there were differences in Leu-1+ B cells, Leu-8+ B cells, Fc epsilon R+B cells (Leu-16+, Leu-20+), and activated B cells (Leu-12+, Leu-21+) between patients with inflammatory bowel disease and normal control subjects. These differences are compatible with local activation of B cells in the inflamed colon.

Mononuclear cells in peripheral venous blood of patients with Crohn's disease: preoperative status and postoperative course, influence of duration, activity and extent of disease

In Crohn's disease (CD) the intestinal lesion is supposed to be the cause of the observed systemic immunologic changes. Based on this assumption, peripheral blood mononuclear cells (PBMC) are of specific interest as a possible indicator of intestinal activity of the disease. From 151 surgical patients CD3+, CD4+, CD8+, B cells, macrophages, leucocytes and the relative number of lymphocytes were analysed preoperatively and 10 days, 3 and 6 months postoperatively. The cell data were correlated with the main clinical data of disease. There was a highly significant preoperative increase of leucocytes, macrophages, CD8+, and B cells in the CD group, and a marked decrease of CD3+, CD4+ cells, and the relative lymphocyte count in the same group. Six months postoperatively, highly elevated macrophages, and leucocytes, and a depressed number of CD4+ cells were the only changes. The preoperative cell data did not correlate with the duration of illness, CDAI, localisation, and extent of the intestinal lesion nor did they correlate with any modality of preoperative drug treatment. Thus, the determination of PBMC characteristics in CD is only of limited value for routine diagnostic purposes. However, the persistence of some pathological values long after operation might be caused by residual microscopic lesions and thus reflect the intestinal process.

Impaired regulation of natural killer cells in immunoglobulin synthesis by peripheral blood mononuclear cells from patients with ulcerative colitis

Immunoglobulin (Ig) synthesis, natural killer (NK) cell activity, and lymphokine production by peripheral blood mononuclear cells (PBMC) were studied in 34 patients with ulcerative colitis (UC). Levels of Ig produced by PBMC were significantly higher in patients with active UC as compared to controls. However, there were no significant differences in Ig-synthesis between patients with inactive UC and controls. NK cell activity was significantly decreased in patients with active UC as compared to controls, and a significant negative correlation was observed between the level of IgA and NK cell activity in patients with UC. Reconstitution experiments demonstrated that CD56+ cells from controls suppressed the levels of IgA, when added to the culture containing a constant number of B cells and CD4+ cells. In contrast, CD56+ cells from patients with active UC completely lacked the capacity to suppress IgA production. In addition, the activities of interleukin-2 and interferon-gamma were significantly decreased in patients with active UC. The present study suggests that immunoregulatory abnormality of NK cells exists in patients with UC and impaired NK cell activity may be related to increased Ig-synthesis observed in these patients.

Immune events associated with inflammatory bowel disease

Immunologic abnormalities have been implicated in the etiology of inflammatory bowel disease (IBD). Defects of systemic immunity and of local (intestinal) immunity have been studied. The numbers of T and B lymphocytes and their characteristics seem to vary with the disease, but no cause-and-effect relationship has been established. The presence of anticolon antibodies in patients with ulcerative colitis suggests that these antibodies could be involved in IBD, but they have also been found in other conditions. In the peripheral blood, abnormalities of cell-mediated immunity are inconsistent and suggest that they are not fundamental defects of the disease. The hypothesis that the inflammatory process is a result of immune-mediated intestinal tissue damage is being extensively studied. The high familial incidence of the disease suggests a role of histocompatibility locus antigens, but no reproducible association can be established. In vivo and in vitro studies of mucosal mononuclear cells have revealed abnormalities of immunoglobulin production, some types of cytotoxicity against gut-derived antigens, and altered lymphokine production associated with the disease. Further studies of the intestinal immune system would seem to be the most fruitful line of research.

Analysis of T lymphocyte subsets in tamarins with colitis and colon cancer

The cotton-top tamarin, Saguinus oedipus, serves as an animal model for the study of human colon cancer. This New World monkey has a high incidence of colitis and colon cancer that develops spontaneously. Evidence suggests that these diseases may be the result of a virally induced immunodeficiency. We have shown that T4+/T8+ cell ratios are significantly altered in tamarins with acute colitis and colon cancers. The T4+/T8+ ratios were 1.50 +/- 0.09, 0.70 +/- 0.05, and 0.48 +/- 0.05 for negative controls, acute colitis, and cancer positive tamarins, respectively. Statistical analysis showed a significant difference (p less than or equal to .0005) between negative controls vs. acute colitis and cancer positive groups.

Crohn's disease and the mycobacterioses: a review and comparison of two disease entities

Crohn's disease is a chronic granulomatous ileocolitis, of unknown etiology, which generally affects the patient during the prime of life. Medical treatment is supportive at best, and patients afflicted with this disorder generally live with chronic pain, in and out of hospitals, throughout their lives. The disease bears the name of the investigator who convincingly distinguished this disease from intestinal tuberculosis in 1932. This distinction was not universally accepted, and the notion of a mycobacterial etiology has never been fully dismissed. Nevertheless, it was 46 years after the distinction of Crohn's disease and intestinal tuberculosis before research attempting to reassociate mycobacteria and Crohn's disease was published. Recently, there has been a surge of interest in the possible association of mycobacteria and Crohn's disease due largely to the isolation of genetically identical pathogenic Mycobacterium paratuberculosis from several patients with Crohn's disease in the United States, the Netherlands, Australia, and France. These pathogenic organisms have been isolated from only a few patients, and direct evidence for their involvement in the disease process is not clear; however, M. paratuberculosis is an obligate intracellular organism and strict pathogen, which strongly suggests some etiologic role. Immunologic evidence of a mycobacterial etiology, as assessed by humoral immune determinations, has been conflicting, but evaluation of the more relevant cellular immunity has not been performed. Data from histochemical searches for mycobacteria in Crohn's disease tissues have been equally conflicting, with acid-fast bacilli detected in 0 to 35% of patients. Animal model studies have demonstrated the pathogenic potential of isolates as well as elucidated the complexity of mycobacterial-intestinal interactions. Treatment of Crohn's disease patients with antimycobacterial agent has not been fully assessed, although case reports suggest efficacy. The similarities in the pathology, epidemiology, and chemotherapy of Crohn's disease and the mycobacterioses are discussed. The issue is fraught with controversy, and the data generated on the association of mycobacteria and Crohn's disease are in their infantile stages so that a general conclusion on the legitimacy of this association cannot be made. While no firm evidence clearly implicates mycobacteria as an etiologic agent of Crohn's disease, the notion is supported by suggestive and circumstantial evidence and a remarkable similarity of Crohn's disease to known mycobacterial diseases.

Fulminant Kaposi's sarcoma complicating long-term corticosteroid therapy

Cutaneous Kaposi's sarcoma occurs rarely in patients receiving long-term corticosteroid therapy. The case of a rapidly progressive form of Kaposi's sarcoma occurring in a 29-year-old Palestinian woman with steroid-dependent Crohn's disease and familial Mediterranean fever is reported. Despite an extensive transfusion history, serologic and virologic studies failed to demonstrate exposure to the human immunodeficiency virus. Serologic and virologic evidence of concomitant cytomegalovirus infection, however, suggests possible pathogenic features similar to the acquired immunodeficiency syndrome-related form of Kaposi's sarcoma.

Lymphocyte subpopulations, lymphoblast transformation activity, and concanavalin A-induced suppressor activity in patients with ulcerative colitis and Crohn's disease

The following immunologic in vitro tests were applied on peripheral blood mononuclear cells (PBMC) from patients with chronic inflammatory bowel disease (IBD): concanavalin A (Con A)-induced suppressor test, Con A-activated lymphoblast transformation test, and spontaneous lymphoblast transformation test. Concomitant phenotypic characterization of subsets of PBMC was performed with monoclonal antibodies. Patients with ulcerative colitis and a control group with rheumatoid arthritis showed significantly reduced activity in the Con A-activated lymphoblast transformation test compared with healthy controls and patients with Crohn's disease. The distribution of PBMC subsets and the results of the other in vitro tests were similar for patients with IBD and healthy controls. Thus the decrease in Con A-activated lymphoblast activity was not due to an increased suppressor function as measured either by functional Con A-induced suppressor test or indirectly by T8 phenotype.

Lymphocyte subsets in primary sclerosing cholangitis

As an initial step in testing the hypothesis that immunoregulatory abnormalities are important in the pathogenesis of primary sclerosing cholangitis, we determined the number and percentage of lymphocyte subsets in the peripheral blood of 33 patients with primary sclerosing cholangitis. In these patients, when compared with normal and diseased controls, there was a significant reduction in the total number of circulating T cells because of a disproportionate decrease in Leu-2a (suppressor/cytotoxic) cells. This decrease resulted in a significantly increased ratio of Leu-3a to Leu-2a cells. Patients with cirrhosis had significantly higher Leu-3a/Leu-2a (helper/suppressor) ratios than did noncirrhotic patients; both disease groups, however, had ratios that were significantly higher than controls. The number and percentage of B cells were significantly increased. Alterations in the percentage of B cells correlated significantly with histologic stage and concentrations of gamma globulin, serum IgG, and bilirubin. We conclude that these abnormalities are suggestive of a defect in immunoregulation in primary sclerosing cholangitis, which is not secondary to advanced liver disease alone and appears to be independent of chronic ulcerative colitis or obstructive jaundice.

A simple index relating clinical activity in Crohn's disease with T cell activation: hematocrit, frequency of liquid stools and urinary neopterin as parameters

Crohn's disease is characterized by alternating acute and quiescent periods. Several indices for activity of the inflammatory process have been proposed to have criteria for prognosis of the clinical course and therapeutic efficacy. Neopterin is specifically released from human monocytes-macrophages after induction by interferon-gamma secreted from activated human T lymphocytes. Thus, urinary neopterin excretion is elevated in diseases involving activation of cellular immunity. Fifteen clinical and laboratory parameters, including urinary neopterin levels, collected from 35 visits of patients with Crohn's disease, were compared using multiple linear regression analysis with a simple clinical activity index as reference. Prediction of clinical activity was best with the combination of hematocrit, weekly number of liquid stools and neopterin. A simple triple-parametric Crohn's disease activity index was established on the basis of this result. Its quality was tested on independent data obtained from 25 repeat visits of 13 of these patients. A comparison with the well-known Crohn's Disease Activity Index (CDAI) was performed. The results obtained with the proposed activity index were slightly better than those with the eight-parametric CDAI for the data from the first as well as from the repeat visits. We conclude that our simple index is a reliable and easily accessible measure for clinical activity in patients with Crohn's disease.

Spontaneous allergic autocytotoxicity in bronchial asthma associated with food allergy

Spontaneous allergic autocytotoxicity of white blood cells was assessed in six patients with bronchial asthma and 18 normal control volunteers. The observed alterations in non-primed white blood cell membrane were revealed as an increased uptake of trypan blue exclusion dye, an indicator of cell death. The phenomenon of spontaneous allergic autocytotoxicity might be associated with increased permeability of the white blood cell membrane leading to enhanced releasability of chemical mediators of anaphylaxis, which probably bypasses immunoglobulin E mechanisms and T suppressor cell intervention. Of six patients with bronchial asthma, three were sensitive to wheat, two had cows milk sensitivity, and one had corn sensitivity. When white blood cells of these patients were studied in the direct allergic autocytotoxicity assay, augmentation of spontaneous allergic autocytotoxicity by specific food antigens was observed. Two of the patients were professional sports coaches. It is plausible to suggest that increased membrane permeability, presumably indicating increased releasability (i.e., for histamine), may be associated with a low membrane threshold for physical trauma expressed in exercise-induced anaphylaxis syndromes.

[Effect of intestinal resection on the behavior of mononuclear subpopulations in Crohn disease]

The literature data about the distribution of mononuclear cells in Crohn's disease are still contradictory. In 50 surgical C.D. patients, clinically classified corresponding to the Crohn's Disease Activity Index (CDAI), the T-lymphocytes and their subsets helper-T- and suppressor-T-lymphocytes (TH/TS) were therefore determined by use of monoclonal antisera, the B-lymphocytes by F(a b)-anti human Ig and the macrophages by uptake of latex microparticles. 37 C.D. patients underwent diseased bowel removal. Blood was drawn from the Crohn-draining mesenteric vein for analysis. Further investigations were performed at the 10th p. op. day as well as after an average period of 7 months (2-18). In comparison the mononuclear cell distribution was examined in 14 patients suffering from chronic osteitis and in 14 patients without any inflammatory disease as controls. C.D. patients showed preoperatively a significantly decreased TH/TS-ratio as well as a significantly increased proportion of macrophages. There was a lymphocytopenia in the peripheral differential blood count. Whereas the distribution of mononuclear subpopulations in the mesenteric blood was identical to the peripheral blood, significant lymphocytosis in the differential blood count of mesenteric blood was found. On the 10th p. op. day the TH/TS-ratio rose almost up to normal, which continued during the follow-up period. The macrophages remained constantly increased in all stages of investigation although during the follow-up none of the patients had signs of disease recurrence. Osteitis patients showed a similar distribution as C.D. patients, even if the changes compared to controls were not as distinct. The proportion of B-lymphocytes was the same in all groups examined. The individual TH/TS-ratios and proportions of macrophages of C.D. patients did not correlate to their clinical data. The changes within the T-cell-subpopulations seem to reflect less M. Crohn's disease itself than its inflammatory complications. Further studies have to be undertaken concerning the impact of the constant increase in macrophages, even after resection of the Crohn bearing bowel segment.

Urinary neopterin, a marker of clinical activity in patients with Crohn's disease

Urinary neopterin excretion was measured in 34 patients with Crohn's disease. Neopterin excretion showed a significant correlation with disease activity using a clinical activity score. An interacting effect of previous medical or surgical therapy on neopterin excretion could be ruled out. Disease localization and extent did not exert any influence on neopterin excretion. Neopterin values were significantly correlated with disease duration, body weight and the presence of a palpable abdominal mass. Multiple stepwise regression analyses identified the combination of neopterin, hematocrit, weekly stool frequency, palpable abdominal mass and related symptoms as predicting clinical activity better than Crohn's Disease Activity Index (CDAI). Thus, neopterin determination may be introduced as an additional biochemical parameter in the assessment of disease activity.

Broncho-Vaxom and spontaneous allergic autocytotoxicity (spACT) in bronchial asthma associated with food hypersensitivity

Spontaneous allergic autocytotoxicity (spACT) of white blood cells (WBC) was assessed in six bronchial asthma patients and eighteen normal control individuals. The observed alterations of non-primed WBC membrane were revealed as an increased uptake of trypan blue exclusion dye, an indicator of death cells. The phenomenon of spACT might be associated with a lack of T suppressor cell intervention, increased refractoriness of WBC membrane leading to its increased permeability and enhanced releasability of chemical mediators of anaphylaxis, which probably bypasses IgE events. In six bronchial asthma patients, three were sensitive toward wheat, two had cow milk sensitivity, and one had corn sensitivity. When WBC of these patients were studied in the direct ACT assay, an additional augmentation of spACT effect by specific food antigens was observed. Surprisingly, Broncho-Vaxom (BX) did not inhibit or enhance spACT. However, BX has antagonistic activity toward direct ACT response in the dose-dependent concentration as previously reported. Our preliminary clinical experience leads us to believe that the spACT assay can serve as a useful clinical discriminator of potential responders versus non-responders to therapy with new agents, when WBC disintegration by autoinduction is involved.

Immunology of inflammatory bowel disease

Although the aetiology of ulcerative colitis and Crohn's disease remain unknown, immunological effector mechanisms become activated within the inflamed mucosa and may be responsible for the pathogenesis of chronic disease. There is an increased production of immunoglobulin within the mucosa, some of which has specificity for bacterial antigens, and complement activation occurs during exacerbation of the disease. Lymphocytes isolated from peripheral blood, or from the intestinal mucosa, are cytotoxic to colonic epithelial cells in vitro; a reaction which can be modulated by serum factors and bacterial antigens. Within the mucosa, there are increased populations of T lymphocytes although there is no change in the ratio of helper- to suppressor-cells as defined by phenotype. Studies of immunoregulatory control have shown that there may be alterations in the modulation of the local immune response, especially during active disease, although it is not clear whether these changes are primary or merely secondary to inflammation. It is posulated that many of the humoral and cellular responses to gut-associated antigens occur as a result of increased antigen absorption, increased presentation of antigen to the immune system due to the expression of Class II antigens by the inflamed epithelium and altered immuno-regulatory control.