Analysis of the lympho-plasmacytic infiltrate in Crohn's disease with special reference to identification of lymphocyte-subpopulations

Myasthenia Gravis: paradox versus paradigm in autoimmunity

Myasthenia Gravis (MG) is a paradigm of organ-specific autoimmune disease (AID). It is mediated by antibodies that target the neuromuscular junction. The purpose of this review is to place MG in the general context of autoimmunity, to summarize the common mechanisms between MG and other AIDs, and to describe the specific mechanisms of MG. We have chosen the most common organ-specific AIDs to compare with MG: type 1 diabetes mellitus (T1DM), autoimmune thyroid diseases (AITD), multiple sclerosis (MS), some systemic AIDs (systemic lupus erythematous (SLE), rheumatoid arthritis (RA), Sjogren's syndrome (SS)), as well as inflammatory diseases of the gut and liver (celiac disease (CeD), Crohn's disease (CD), and primary biliary cirrhosis (PBC)). Several features are similar between all AIDs, suggesting that common pathogenic mechanisms lead to their development. In this review, we address the predisposing factors (genetic, epigenetic, hormones, vitamin D, microbiota), the triggering components (infections, drugs) and their interactions with the immune system [1,2]. The dysregulation of the immune system is detailed and includes the role of B cells, Treg cells, Th17 and cytokines. We particularly focused on the role of TNF-α and interferon type I whose role in MG is very analogous to that in several other AIDS. The implication of AIRE, a key factor in central tolerance is also discussed. Finally, if MG is a prototype of AIDS, it has a clear specificity compared to the other AIDS, by the fact that the target organ, the muscle, is not the site of immune infiltration and B cell expansion, but exclusively that of antibody-mediated pathogenic mechanisms. By contrast, the thymus in the early onset subtype frequently undergoes tissue remodeling, resulting in the development of ectopic germinal centers surrounded by high endothelial venules (HEV), as observed in the target organs of many other AIDs.

Increased levels of survivin, via association with heat shock protein 90, in mucosal T cells from patients with Crohn's disease

BACKGROUND & AIMS

Defective apoptosis of lamina propria T cells (LPTs) is involved in the pathogenesis of Crohn's disease. Survivin, a member of the inhibitors of apoptosis family, prevents cell death and regulates cell division. Survivin has been studied extensively in cancer, but little is known about its role in Crohn's disease.

METHODS

LPTs were isolated from mucosal samples of patients with Crohn's disease or ulcerative colitis and healthy individuals (controls). LPTs were activated with interleukin-2 or via CD3, CD2, and CD28 signaling, and cultured at 42°C to induce heat shock. Survivin expression was assessed by immunohistochemistry, confocal microscopy, and immunoblotting; survivin levels were reduced by RNA interference. Cell viability, apoptosis, and proliferation were measured by trypan blue exclusion, annexin-V/7-Aminoactinomycin D staining, and uptake of [3]thymidine, respectively.

RESULTS

LPTs from patients with Crohn's disease had higher levels of survivin than LPTs from patients with ulcerative colitis or controls. RNA knockdown of survivin in LPTs inhibited their proliferation and promoted apoptosis. Levels of survivin were low in LPTs from patients with ulcerative colitis and controls as a result of ubiquitin-mediated proteasome degradation. In LPTs from patients with Crohn's disease, survivin bound to the heat shock protein (HSP)90, and therefore was resistant to proteasome degradation. Incubating LPTs with 17-N-allylamino-17-demethoxygeldanamycin, an inhibitor of HSP90, reduced levels of survivin and induced apoptosis.

CONCLUSIONS

Levels of survivin are increased in LPTs from patients with Crohn's disease (compared with ulcerative colitis and controls) because survivin interacts with HSP90 and prevents proteasome degradation. This allows LPTs to avoid apoptosis. Strategies to restore apoptosis to these cells might be developed to treat patients with Crohn's disease.

A hexane fraction of American ginseng suppresses mouse colitis and associated colon cancer: anti-inflammatory and proapoptotic mechanisms

Ulcerative colitis is a chronic inflammatory condition associated with a high colon cancer risk. We have previously reported that American ginseng extract significantly reduced the inflammatory parameters of chemically induced colitis. The aim of this study was to further delineate the components of American ginseng that suppress colitis and prevent colon cancer. Among five different fractions of American ginseng (butanol, hexane, ethylacetate, dichloromethane, and water), a hexane fraction has particularly potent antioxidant and proapoptotic properties. The effects of this fraction were shown in a mouse macrophage cell line (ANA-1 cells), in a human lymphoblastoid cell line (TK6), and in an ex vivo model (CD4(+)/CD25(-) primary effector T cells). A key in vivo finding was that compared with the whole American ginseng extract, the hexane fraction of American ginseng was more potent in treating colitis in a dextran sodium sulfate (DSS) mouse model, as well as suppressing azoxymethane/DSS-induced colon cancer. Furthermore, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) labeling of inflammatory cells within the colonic mesenteric lymph nodes was elevated in mice consuming DSS + the hexane fraction of American ginseng. Results are consistent with our in vitro data and with the hypothesis that the hexane fraction of American ginseng has anti-inflammatory properties and drives inflammatory cell apoptosis in vivo, providing a mechanism by which this fraction protects from colitis in this DSS mouse model. This study moves us closer to understanding the molecular components of American ginseng that suppress colitis and prevent colon cancer associated with colitis.

Colonic IgA producing cells and macrophages are reduced in recurrent and non-recurrent Clostridium difficile associated diarrhoea

BACKGROUND

In Clostridium difficile associated diarrhoea (CDAD), histological changes in the colonic mucosa range from minimal inflammation to pseudomembranous colitis (PMC). The disease also recurs in a considerable proportion of patients.

AIM

To investigate mucosal immune system cells in colonic biopsies of patients with CDAD.

METHODS

Colonic biopsies were obtained from 12 control patients with diarrhoea, six patients with CDAD and minimal inflammation, and 10 patients with CDAD with pseudomembranous colitis (samples obtained from areas with and without inflammatory exudate). Immunohistochemical studies were performed using antibodies to T cells (CD3), macrophages (CD68), B/plasma cells (CD79alpha), and to IgA, IgM, and IgG. Labelled cells in lamina propria were quantified.

RESULTS

In contrast to T cells, there were significant reductions in B/plasma cell and macrophage counts in all biopsies from patients with CDAD compared with controls (p<0.001). Studies using anti-immunoglobulin antibodies showed significant reductions in IgA producing cells in CDAD biopsies (p<0.05), with the greatest reduction in samples from patients with PMC. In contrast, there was a significant increase (p<0.05) in IgG producing cells in CDAD biopsies. Only patients with PMC relapsed. In these patients, B/plasma cell and IgA producing cell counts (in biopsies with and without inflammatory exudates) were significantly lower (p<0.01) in mucosal samples from those who subsequently relapsed (five) than those who did not.

CONCLUSIONS

A selective reduction in mucosal IgA producing cells and macrophages is associated with colonic disease in C difficile infected patients. Severe reduction in colonic IgA producing cells may predispose to recurrence of CDAD.

Intraepithelial lymphocytes: exploring the Third Way in immunology

Locally resident intraepithelial lymphocytes (IELs) are primarily T cells with potent cytolytic and immunoregulatory capacities, which they use to sustain epithelial integrity. Here, we consider that most IEL compartments comprise a variable mixture of two cell types: T cells primed to conventional antigen in the systemic compartment and T cells with ill-defined reactivities and origins, whose properties seem to place them mid-way between the adaptive and innate immune responses. We review the capacity of IELs to limit the dissemination of infectious pathogens and malignant cells and to control the infiltration of epithelial surfaces by systemic cells. An improved characterization of IELs would seem essential if we are to understand how immune responses and immunopathologies develop at body surfaces.

An immunohistochemical study of histiocytic ulcerative colitis in boxer dogs

Histiocytic ulcerative colitis (HUC) is an inflammatory bowel disease (IBD) that occurs predominantly in dogs of the boxer breed. The lesions are characterized by mucosal ulceration and mixed inflammatory cell infiltrate that includes the presence of periodic acid-Schiff (PAS)-positive macrophages. However, the phenotype of the inflammatory cells has not been characterized further. In the present study, immunohistochemistry and computer-aided morphometric analysis were used to define populations of leucocyte subsets in the colon of 14 boxer dogs with HUC. Biopsies from six of these dogs included both lesional and non-lesional regions. Colonic tissue from 11 dogs of various breeds without evidence of gastrointestinal disease served as controls. In HUC lesions there were significantly more IgG(+), IgG3(+), IgG4(+)plasma cells, CD3(+)T cells, MHC class II(+)cells, L1(+)cells and PAS(+)cells in the lamina propria than in both control colon and non-lesional colonic regions of affected dogs. In the epithelial compartment, goblet cells were significantly decreased in HUC lesions compared to both control and non-lesional HUC colon, and intensity of enterocyte MHC class II expression was significantly increased. These observations are similar to those documented in human IBD, especially ulcerative colitis, and suggest an important role for the mucosal immune system in the pathogenesis of canine HUC.

Evaluation of B and T lymphocytes and plasma cells in colonic mucosa from healthy dogs and from dogs with inflammatory bowel disease

The aim of this study was to investigate the subpopulations of lymphocytes in the colonic mucosa of healthy dogs and dogs with inflammatory bowel disease (IBD). Fourteen normal dogs and 13 dogs with IBD were examined. Endoscopic biopsy specimens of colonic mucosa from each dog were stained specifically for pan T lymphocytes (CD3) and pan B lymphocytes (CD79a), and for plasma cells with methyl green pyronin (MGP) stain. Cells were counted by means of a grid and statistical analysis was performed on the data collected. B and T lymphocytes were also counted in the glandular epithelium of normal dogs and dogs with IBD and the normal and abnormal groups compared statistically. Healthy dogs had significantly lower numbers of T cells in the lamina propria and glandular epithelium and significantly lower numbers of B cells in the lamina propria. Significant group differences for plasma cells were not evident. Our results indicate that in IBD a chronic cellular immune reaction is present in the diseased gut involving increased numbers of B and T lymphocytes.

Type 1 T-helper cell predominance and interleukin-12 expression in the gut of patients with Crohn's disease

Crohn's disease (CD) is a chronic bowel inflammatory disorder in which the pathogenic role of immune alterations has been suggested, but the immunologic mechanisms responsible for the inflammatory reaction are still poorly understood. We investigated the profile of cytokine secretion by T-cell clones generated from gut tissue specimens of four patients with active CD, five patients with ulcerative colitis, and four patients with noninflammatory gut disorders (NIGDs). The great majority of CD4+ T-cell clones generated from the gut of patients with CD produced high levels of interferon-gamma (IFN-gamma) but low or undetectable amounts of interleukin-4 (IL-4), whereas substantial proportions of CD4+ T-cell clones derived from the gut of patients with either ulcerative colitis or NIGDs produced IL-4 in addition to IFN-gamma. The immunohistochemical analysis revealed high numbers of activated CD4+ T cells showing IFN-gamma but not IL-4 reactivity, as well as substantial proportions of IL-12-containing macrophages, in the intestinal lamina propria and muscularis propria of patients with CD, whereas these cells were very rare or undetectable in patients with NIGDs. Culturing T cells from gut biopsy specimens of a patient with CD in the presence of a neutralizing anti-IL-12 antibody down-regulated the development of IFN-gamma-producing CD4+ T cells. These findings suggest that a critical event in the initiation of bowel inflammatory lesions in CD may involve up-regulation of IL-12 production, resulting in conditions that maximally promote type 1 T-helper immune responses.

Inflammatory bowel disease in C.B-17 scid mice reconstituted with the CD45RBhigh subset of CD4+ T cells

Chronic inflammation developed spontaneously in the large intestine of C.B-17 scid mice restored with the CD45RBhigh subset of CD4+ T cells obtained from normal BALB/c mice. The inflammation, which extended diffusely from the cecum to the rectum, was localized to the lamina propria of mildly affected mice but became transmural in severely affected mice. Immunohistochemical and flow cytometric analyses showed that the inflammatory infiltrate contained numerous macrophages accompanied by moderate numbers of activated CD4+ lymphocytes. Some mice also had scattered multinucleated giant cells. Mucin depletion and epithelial hyperplasia resulting in glandular elongation and mucosal thickening were also consistently seen. Less frequent findings included ulceration with fibrosis, crypt abscesses, crypt loss, and granulomatous inflammation. Immunofluorescent analysis of inflamed large intestinal sections demonstrated increased epithelial expression of major histocompatibility class II antigens. The changes in the large intestine of these mice are similar to those seen in patients with idiopathic inflammatory bowel disease (Crohn's disease and ulcerative colitis). This murine model may be useful for studying mucosal immunoregulation as it relates to the pathogenesis and treatment of chronic inflammatory bowel diseases in the large intestine of human patients.

Decreased mucosal IgA levels in ileum of patients with chronic ulcerative colitis

Patients with chronic ulcerative colitis (CUC) are known to have decreased spontaneous IgA secretion by colonic mononuclear cells. The aim of this study was to determine whether a similar alteration exists in the apparently healthy ileum of patients with CUC. The concentration of IgA was measured in the supernatant from homogenized mucosal ileal biopsies using a sandwich-type ELISA. The concentration of IgA was significantly (P = 0.025) decreased in the ileum of patients with CUC (N = 24) in comparison to normal ileum (N = 10). The number of mucosal IgA-containing mononuclear cells (MNC) was also determined using an avidin-biotin-immunoperoxidase technique on paraffin-embedded ileal sections. Although reduced, the number of positive cells and their distribution was not significantly different in the ileum of patients with CUC (N = 20) when compared to normal ileum (N = 10). We suggest that decreased mucosal IgA levels are a panintestinal condition in CUC and that this is a primary alteration rather than a secondary response to the inflammatory process. Considering the role of IgA, we propose that decreased mucosal IgA levels in CUC may predispose to the disease by a reduction of the immune-mediated exclusion mechanism and/or by an impairment of the down-regulation of the inflammatory response.

Evidence for an altered T-cell receptor repertoire in Crohn's disease

We have compared the frequencies of T cells expressing each of four different T cell receptor (TCR) V beta segments in lamina propria and peripheral blood lymphocytes of 12 Crohn's disease (CD), six ulcerative colitis (UC), and 10 control patients in an attempt to identify disease-specific changes. The frequencies of CD4+ and CD8+ cells reacting with each of four fluoresceinated TCR-specific monoclonal antibodies directed against V beta 5, V beta 6.7a, V beta 8, and V beta 12 were determined by flow cytometry. There was no difference among the groups in the average frequency of any single V beta segment in either the CD4+ or CD8+ subpopulations. However, when the sum of the differences in V beta frequencies (delta score) between peripheral blood lymphocytes (PBL) and lamina propria lymphocytes (LPL) were determined for each individual, significant differences were observed between the CD4+ and CD8+ populations and among the patient groups. In all three patient groups, there were significant individual differences between LPL and PBL in the frequencies of CD8+ and CD4+ cells reacting with the four V beta-specific mAb. In Controls and UC, this difference was, on average, two-fold greater in CD8+ cells than in CD4+. In CD, however, this difference was, on average, the same for CD8+ and CD4+ cells. These observations suggest that (1) the human colonic LPL TCR repertoire is normally different from that of PBL, especially in the CD8+ population and (2) there is an alteration in the LPL TCR repertoire in CD which is not observed in Controls or UC.

Increased interleukin-2 messenger RNA in the intestinal mucosal lesions of Crohn's disease but not ulcerative colitis

Crohn's disease (CD) is characterized by granulomatous inflammation of the intestinal mucosa, but the etiology and pathogenesis of the inflammatory lesions are unknown. The aim of this study was to determine whether T-cell activation and lymphokine production occurs in the mucosal lesions of this disease. Total cellular RNA was isolated from peripheral blood lymphocytes and from colonoscopic mucosal biopsies of normal individuals and patients with CD of the colon or ulcerative colitis (UC). Levels of interleukin-2 (IL-2) messenger RNA (mRNA) transcripts in samples were determined using a quantitative reverse transcriptase polymerase chain reaction method. IL-2 mRNA transcripts were detected in histologically normal intestinal mucosal biopsies obtained from control subjects. In CD, higher levels of IL-2 mRNA transcripts were detected in the mucosa from areas of active inflammation, but in areas that were histologically normal, levels were similar to control subjects. The levels of IL-2 mRNA transcripts in biopsies from active and inactive UC were similar to control subjects. Levels of IL-2 mRNA in peripheral blood lymphocytes were low and not significantly different in all groups of subjects. In conclusion, the normal intestinal mucosa contains IL-2 mRNA transcripts and may be an important source of IL-2. Furthermore, the inflammatory lesions of CD, but not UC, have higher levels of IL-2 mRNA transcripts, suggesting that T-cell activation and lymphokine secretion in the intestine may be important in the pathogenesis of CD. These data provide further evidence that the pathogenesis of CD and UC are different.

Value of counting colonic mucosal Ig-containing cells in the differential diagnosis of chronic inflammatory bowel disease

AIMS

To investigate whether counting cells containing immunoglobulin (Ig) subclass in colonic biopsy specimens of patients with chronic inflammatory bowel disease, in addition to conventional histological evaluation, can improve the differentiation of patients with Crohn's disease from those with ulcerative colitis.

METHODS

The colonic and rectal biopsy specimens of 40 patients with chronic inflammatory bowel disease, comprising 20 patients with Crohn's disease and 20 with ulcerative colitis, were used and sections were stained specifically for IgA, IgM, and IgG heavy chains using an indirect immune peroxidase method. The immunoglobulin subclass containing cells were counted using an ocular grid counting method in a light microscope. A linear stepwise discriminant analysis was performed on Ig subclass containing cell counts in combination with 16 reproducible histological features. The results of this discriminant analysis were compared with the results of the discriminant analyses in which only the histological features were used.

RESULTS

Applying stepwise discriminant analysis, two histological features (an excess of histiocytes in the lamina propria and the villous or irregular aspect of the mucosal surface) in combination with IgMax were selected as the most discriminatory parameters that distinguish Crohn's disease from ulcerative colitis. IgMmax was defined as the maximum value of the mean percentage of IgM containing cells over all the biopsy locations. The use of this combination resulted in a better classification in 20% of the patients with Crohn's disease and in 9% of the patients with ulcerative colitis compared with the use of histological features alone.

CONCLUSIONS

Morphometric enumeration of Ig subclass containing cells in colonic mucosal biopsy specimens has diagnostic value as a means of differentiating individual patients with Crohn's disease from those with ulcerative colitis.

Histopathological evaluation of colonic mucosal biopsy specimens in chronic inflammatory bowel disease: diagnostic implications

In a prospective blind evaluation of multiple colonic mucosal biopsy specimens, 45 clinically well defined patients with chronic inflammatory bowel disease (21 Crohn's disease and 24 ulcerative colitis) and 16 control subjects (seven normal subjects and nine patients with diverticular disease) were studied to identify reproducible histopathological features which could distinguish chronic inflammatory bowel disease (CIBD) from non-CIBD and Crohn's disease from ulcerative colitis. Using kappa statistics 16 of 41 histological features were sufficiently reproducible for further stepwise discriminant analysis to differentiate between CIBD and non-CIBD, and between Crohn's disease and ulcerative colitis. Using the combination of three features (an increase of lymphocytes and plasma cells in the lamina propria, the presence of branching of crypts, and neutrophils in the crypt epithelium) we were able to distinguish CIBD from non-CIBD in 89% of the cases with high probability (p greater than 0.85). To separate Crohn's disease from ulcerative colitis three features (an excess of histiocytes in combination with a villous or irregular aspect of the mucosal surface and granulomas) had a high predictive value. Using these features 70% of Crohn's disease patients and 75% of ulcerative colitis patients were correctly classified with a high probability (p greater than 0.85). These findings indicate that the pathologist is dependent on the presence of only a few histological features for a reliable classification of Crohn's disease and ulcerative colitis.

Immunohistological studies of surface antigen on colonic lymphoid cells in normal and inflamed mucosa. Comparison of follicular and lamina propria lymphocytes

Mucosal samples from 16 patients with idiopathic inflammatory bowel disease were examined immunohistologically using several monoclonal antibody combinations, and the results were compared with those obtained in other colonic inflammatory disorders and in normal mucosa. Within and around lymphoid follicles, most T cells expressed the restricted common leucocyte antigen (CD45R, displayed by unprimed T cells). Conversely, most lamina propria T cells were negative for CD45R but stained positively with UCHL1 (a monoclonal antibody recognizing an antigen displayed by primed T lymphocytes). The proportions of T-lymphocyte subpopulations in normal and inflamed mucosa were similar, except that CD6-negative, CD7-positive cells were significantly more frequent in inflammatory bowel disease. A characteristic feature of ulcerative colitis and Crohn's colitis was marked infiltration by CD45R+ lymphoid cells that did not coexpress T- or B-cell surface antigens; some stained positively with plasma cell reagents, suggesting that they may be activated B cells. The observations in the colitis sections are consistent with the interpretation that T and B cells alter their surface antigen expression as they emerge from follicles and enter the inflamed lamina propria.

Immunological study of histologically non-involved jejunum during Crohn's disease: evidence for reduced in vivo secretion of secretory IgA

We studied the local humoral immunity of histologically non-involved jejunum in patients with Crohn's disease. Normal subjects and patients with ulcerative colitis served as controls. Jejunal fluid samples were collected during segmental jejunal perfusion, under an occluding balloon and the in vivo jejunal secretion of the following proteins was determined: albumin, orosomucoid, transferrin, alpha 2-macroglobulin, secretory component, monomeric and polymeric IgA, IgG, and IgM. The densities and number of IgA-, IgG-, and IgM-containing cells in the lamina propria of the jejunum were measured on perendoscopic biopsies. Jejunal secretion of polymeric IgA and the density of IgA-containing plasma cells in the lamina propria were significantly lower in patients with Crohn's disease than in both control groups. This abnormal intestinal immune response, which was not correlated to the activity of the disease, might be involved in its pathogenesis.

Effect of perioperative blood transfusion on recurrence of Crohn's disease

The effect of perioperative blood transfusion on recurrence of Crohn's disease was investigated retrospectively in 60 patients with Crohn's disease who underwent small-bowel resection. 28 patients received 1-8 units of blood; the others were not transfused. Both groups were similar in age, duration of Crohn's disease, and preoperative serum albumin, but preoperative haemoglobin, length of intestine resected, and location of small-bowel involvement were different. The patients who received perioperative blood transfusion had a significantly lower recurrence rate by life-table analysis, although the site and greater length of bowel involvement in the transfused patients would normally indicate an increased likelihood of recurrence. 5 years after bowel resection, the cumulative recurrence rate in transfused patients was 19%, compared with 59% in controls. The immunosuppressive effect of blood transfusion may modify the progression of Crohn's disease.

Immunoglobulin containing cells in terminal ileum and colorectum of patients with arthritis related gut inflammation

In 40 distal ileal and 40 colonic biopsies of arthritic patients mostly without gastrointestinal symptoms, but with histological evidence of acute or chronic inflammation of the gut, the number of immunoglobulin (Ig) containing plasma cells was studied morphometrically using a peroxidase antiperoxidase technique. Compared with controls, the ileal mucosal biopsies showed an increase of IgA and IgG in acute ileitis. In chronic ileitis there was an increase of IgA, IgG, and IgM similar to Crohn's disease. In colonic biopsies there was a significant increase of all immunoglobulin classes in acute inflammation. In chronic inflamed mucosa there was also an increase of all three Ig classes. The Ig distribution, however, was significantly different in acute and chronic colitis. These findings give immunohistochemical evidence of the existence of two different types of inflammation related to reactive arthritis or the peripheral joint involvement of ankylosing spondylitis. The Ig pattern in acute colitis is similar to that found in infectious colitis, suggesting an enterobacterial origin of the arthritis in this group of patients although bacteriological and serological investigations were negative. In the chronic type of arthritis related ileocolitis, the pattern of Ig containing cells is similar to that found in Crohn's disease but different from infectious and ulcerative colitis, which makes the hypothesis that a great number of these arthritis patients suffer from asymptomatic or subclinical Crohn's disease acceptable.

Changes in small intestinal epithelial expression of MHC class II antigen after terminal ileal resection for Crohn's disease

Aphthous lesions in the neoterminal ileum from patients operated for Crohn's disease are an early sign of recurrence that can be identified during ileocolonoscopy. The origin of these lesions was studied in nine patients treated by terminal ileal resection and right hemicolectomy for complicated Crohn's disease. During surgery the neoterminal ileum was turned inside out, the mucosa was carefully inspected and two large mucosal biopsies were obtained. The same procedure was carried out in seven patients operated for other diseases. Four to six months after surgery endoscopy of the neoterminal ileum was carried out and multiple biopsies were obtained from the neoterminal ileum. Another follow-up colonoscopy with biopsies was carried out one year after the operation. The operative specimens and the per- and postoperative biopsies were submitted to routine microscopy and immuno- and enzyme-histochemistry. None of the Crohn's patients had macroscopic lesions in the neoterminal ileum at operation and only one had microscopic signs of inflammation and a positive section margin. Four-six months after operation all Crohn's patients had active aphthous lesions in a 5-20 cm segment of the neoterminal ileum at endoscopy. Biopsies taken at this time showed microscopic features which were not observed in biopsies from control subjects: an increase of HLA-DR+, ATPase+ dendritic cells in the ileal mucosa and a defective expression of MHC class II antigens by the small intestinal epithelial cells. MHC class II expression by the small intestinal epithelial cells returned towards normal after one year.(ABSTRACT TRUNCATED AT 250 WORDS)

Determination of transferrin receptors on frozen sections of malignant B-cell lymphomas by immunofluorescence with a monoclonal antibody

A series of 34 B-cell lymphomas was studied for the presence of transferrin receptors by immunofluorescence on frozen tissue sections with a monoclonal antibody. These lymphomas were classified by light microscopic study and furthermore investigated by immunohistochemical and morphometric methods. There were diffuse centrocytic, diffuse centroblastic, and follicular and diffuse centrocytic/centroblastic lymphomas. Significant differences in log mean nuclear area in these four histologic groups were found, as well as a significant correlation between log nuclear area and transferrin receptors as measured semiquantitatively by fluorescence intensity of the cell membranes. In addition, it was found that there is a strong correlation between the transferrin receptor activity and malignancy grading on histologic and morphometric basis. Therefore, the transferrin receptor determination on frozen sections appears to be a good method of malignancy grading.

Distribution of immunoglobulin producing cells is different in normal human appendix and colon mucosa

The densities of IgG-, IgA-, IgM- and IgD-producing immunocytes were determined by paired immunofluorescence staining and morphometric analysis in the lamina propria of normal appendix specimens. Normal colon specimens were used as reference material, mostly paired from individual subjects. The density (median of cells/mm2 lamina propria area) of IgA immunocytes tended to be slightly higher in the appendix than in the colon (1259 vs 962) and the same held true for IgM cells (71 vs 55). Conversely, the overall density of IgG immunocytes was much higher in the appendix than in the colon (95 vs 38). A striking feature was the fact that almost 50% of all immunocytes were of the IgG isotype adjacent to lymphoid follicles. It seemed justified to conclude, therefore, that the abundance of such follicles explains the overall enrichment of IgG-producing cells in normal appendix mucosa. These immunocytes most likely represent follicle derived B cells that have reached terminal maturation locally, whereas precursors generated from less mature memory clones probably emigrate and home ubiquitously to distant sites of the gut lamina propria where they develop into IgA-producing immunocytes.

Studies on lymphocyte subpopulations in human colonic biopsy specimens by colonoscopy

Lymphocytes, isolated by the enzymatic technique, from colonic mucosal specimens obtained from eight patients with ulcerative colitis (UC), two with ischemic colitis, two with antibiotic-associated colitis, and 15 controls by colonoscopic biopsy were used to examine T and B cells. In control biopsy specimens, the mononuclear cell yield averaged 3.6 +/- 0.3 (SEM) X 10(6)/g with a viability of 93 +/- 1%, while T and B cells expressed as a percentage of total lymphocyte counts were 65 +/- 1% and 15 +/- 1%, respectively. T and B cells in the ascending, transverse, and sigmoid colon and rectum did not present any differences. In involved tissue at the active stage of UC, the mononuclear cell yield averaged 11.4 +/- 2.1 X 10(6)/g, and T and B cells constituted 49 +/- 3% and 43 +/- 4%, respectively. After treatment for two months with salazosulfapyridine, mononuclear cell yields in five cases of UC were significantly reduced to an average of 3.9 +/- 0.8 X 10(6)/g as compared to the pretreatment level (P less than 0.01). The percentage of T cells was significantly increased from 48 +/- 2% to 62 +/- 2% (P less than 0.01), and that of B cells was significantly reduced from 39 +/- 2% to 27 +/- 3% (P less than 0.01). These results revealed a significant difference in the subpopulations of mucosal lymphocytes in the involved sites in the active stage of UC as compared to normal controls, suggesting that immunological abnormalities may be implicated in the etiology of this disease and that disease remission on salazosulfapyridine treatment is associated with a correction of the colonic lymphocyte abnormalities.

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.

Immunohistological differential diagnosis of inflammatory colonic diseases

Immunohistological investigations were carried out on human colonic tissue from, I healthy mucosa, 2 slightly inflamed mucosa, 3 mucosa with ulcerative colitis, 4 mucosa with Crohn's colitis, using antibodies against immunoglobulins and complement components. All our antibodies, including F(ab')2 fragments, demonstrated a progressive increase of labelled cells from healthy mucosa through slightly inflamed mucosa to mucosa with ulcerative colitis, in contrast to a complete absence of labelled cells in cases of Crohn's disease. The results are discussed with regard to their pathogenesis and their clinical significance for the differentiation of ulcerative colitis and Crohn's colitis.

Veiled cells in chronic idiopathic inflammatory bowel disease

The mononuclear cell system in the human gut wall of patients with Crohn's disease (CD), ulcerative colitis (UC) and normal controls was studied, with special reference to the so called antigen presenting veiled cells. These cells have already extensively been studied in the skin and are known as Langerhans' cells in the epidermis and dermis, veiled cells in the skin lymph and interdigitating cells in lymph nodes. Recently they were also found in gut associated lymphoid tissue, i.e. Peyer's patches of the rat. Here we describe the presence of similar cells in chronic idiopathic inflammatory bowel disease (CIBD). They resemble veiled cells in moving pattern, strong Ia positivity, no or only weak acid phosphatase activity, and ultrastructure. However, many of the described cells combine these characteristics with those of phagocytic macrophages. In the gut wall of controls veiled cells were virtually absent and phagocytic macrophages were almost exclusively recognized. These findings suggest that more intensive antigen handling takes place in the gut wall of CIBD patients than in normal gut. Clear cut associations with sex, age, duration or activity of disease were not observed in this limited study, and the exact significance of the presence of such cells needs further clarification.

Intestinal lymphocyte subpopulations in inflammatory bowel disease: an analysis by immunohistological and cell isolation techniques

Lymphocyte subpopulations in the intestinal mucosa of patients with ulcerative colitis or Crohn's disease have been studied using a double marker immunofluorescence technique. Analysis of tissue sections revealed that the majority of intraepithelial lymphocytes (IEL) were T cells (Hle-1+ HuTLA+ UCHT1+). Of these, over 80% were of suppressor-cytotoxic phenotype (OKT8+:83 +/- 10.2%) with a small population of helper type IEL (OKT4+). Only one third of OKT8+ IEL reacted with the T cell antibody, anti-Leu-1. IEL were also Tac-, C3b-receptor- (C3RT05-), and Ig-. Within the lamina propria, OKT4+ T cells predominated (ulcerative colitis 64 +/- 6.0%; Crohn's disease 63 +/- 6.0%). Less than half of the smaller OKT8+ population in the lamina propria was Leu-1+. These finding did not differ from those seen in histologically normal tissues from controls, and are similar to those reported in the small intestine. Mononuclear cells were also isolated from the intestinal lamina propria using an enzymatic technique. The majority of lymphocytes obtained were T cells (OKT3+), with populations of OKT4+ and OKT8+ cells. Comparison of the ratio of OKT4+ to OKT8+ lymphocytes determined by immunohistological analysis with that obtained in mucosal isolates, however, suggested that the isolation procedure may deplete OKT8+ cells. These findings indicate that an imbalance of mucosal immunoregulatory T cells, as defined by monoclonal antibodies, does not occur in inflammatory bowel disease. They also emphasize that functional studies of isolated intestinal mucosal cells should be combined with morphological studies of cell populations in situ.

Pokeweed mitogen stimulated immunoglobulin production by peripheral blood lymphocytes in vitro: evidence for disordered immunoregulation in patients with ulcerative colitis and Crohn's disease

Production of immunoglobulins (G, A, M) by pokeweed mitogen stimulated peripheral blood lymphocytes was studied in 81 patients with inflammatory bowel disease and compared with 40 patients with mild gastrointestinal disorders (controls). Immunoglobulin production was dependent on the concentration of mononuclear cells in culture, being maximal at the lowest concentration used (2.5 X 10(5)/ml). Adherent monocytes exerted suppression when cultures were reconstituted with more than 20% of these cells. T lymphocyte depleted cells (B cells) demonstrated T cell helper/suppressor dependence for immunoglobulin production in an isotype specific manner, the optimal T cell concentration for 'helper' activity being lowest for IgG and highest for IgM. In patients with active ulcerative colitis (UC) there was a reduction in the T cell concentration for optimal helper activity that was not isotype specific suggesting an increase in non-specific T cell helper activity. T cell helper activity reverted toward control levels in patients with UC in disease remission, except in the case of IgA production where there was a significant diminution of IgA production and of T helper activity for IgA synthesis. Patients with Crohn's disease were distinguished from both UC and control patients by: (1) reduced immunoglobulin production at low lymphocyte concentrations; (2) reduced monocyte-mediated suppression of immunoglobulin production and (3) no shift in T cell concentration for optimal helper activity for IgG and IgA with active disease.

Surgical treatment, skin test reactivity, and lymphocytes in inflammatory bowel disease

Sixty-three patients with inflammatory bowel disease were studied before and after bowel resection. Peripheral lymphocytes, T- and B-cell counts, and skin test reactivity to five recall antigens were determined before operation and 6 to 18 months postoperatively. Twenty-eight patients (44 percent) were unable to react to any skin test initially. Anergic patients had significantly lower lymphocyte and T- and B-cell counts. There was no difference in age, severity or duration of disease, or amount of weight loss between anergic patients and those who responded. Also, there was no difference between patients with ulcerative colitis and those with Crohn's disease. After surgery, 25 previously anergic patients became able to react to skin tests. They also showed a significant increase in T and B cells which did not occur in the previously reactive group. However, the overall peripheral lymphocyte and T- and B-cell counts remained well below those of the normal control subjects. Patients with inflammatory bowel disease that requires surgical treatment have significant immunologic abnormalities. Removal of the diseased bowel, weight gain, and cessation of steroid medication improves skin test reactivity but does not correct the depressed peripheral lymphocyte and especially T-cell counts.

T lymphocyte subsets in inflammatory bowel disease: peripheral blood

Peripheral blood T lymphocytes and T lymphocyte subsets have been quantified in 28 patients with ulcerative colitis and 26 with Crohn's disease by an indirect immunofluorescence technique using monoclonal antibodies: OKT3, which detects all peripheral blood T lymphocytes; OKT4 (T cells of helper phenotype); and OKT8 (T cells of supressor-cytotoxic phenotype). Eighteen normal subjects and 16 patients with a variety of non-inflammatory gastrointestinal disorders were studied as controls. No significant differences were found between patient and control groups in the proportions of circulating T lymphocytes or their subsets. When compared with normal subjects, absolute numbers of T lymphocytes were reduced in patients with active ulcerative colitis or Crohn's disease (p less than 0.05). OKT4+ T cell numbers were reduced in ulcerative colitis, whether active (p less than 0.02) or inactive (p less than 0.05) and in active Crohn's disease (p less than 0.05) Numbers of OKT8+ T cells were reduced in active Crohn's disease (p less than 0.01). There were no differences in T lymphocyte numbers between the patient groups and the disease control subjects. The OKT4+:OKT8+ ratio in patients with inflammatory bowel disease did not differ from that in controls. No relation was found between any of the parameters studied and disease activity, site, or extent of disease, or treatment with sulphasalazine or corticosteroids. The presence of Ia-like, HLA-DR antigens on T cells was detected using a double marker immunofluorescence technique. In control subjects up to 7% of OKT3+ cells were HLA-DR+. In only three patients was the proportion of HLA-DR+ cells greater than in controls. These results indicate that the pathogenesis of ulcerative colitis or Crohn's disease does not depend upon an alteration in the proportion of circulating T lymphocytes nor upon an imbalance of T lymphocyte subsets as defined by monoclonal antibodies. The reduction in T lymphocyte numbers may result from mucosal infiltration. The findings also suggest that circulating T lymphocytes are not activated.

T lymphocyte subsets in human intestinal mucosa: the distribution and relationship to MHC-derived antigens

T lymphocytes in the normal human intestinal tract have been analysed in tissue sections by a double-marker immunofluorescence technique, combining antiserum to T lymphocyte antigen (HuTLA) with a monoclonal antibody detecting T cells of suppressor-cytotoxic phenotype (OKT8). The distribution of HLA-A -B, -C and Ia-like antigens in intestinal mucosa was also examined by a similar method. In small and large intestine 67 to 90% (mean 70%) of intraepithelial T lymphocytes were of suppressor-cytotoxic phenotype (OKT8+). In contrast, only 27 to 56% (mean 39%) of lamina propria T cells were OKT8+. Intestinal epithelial cells demonstrated strong membrane staining for HLA-A, -B, -C antigens. Ia-like antigens were detected on the epithelial cells of small intestinal villi, but not on colonic epithelial cells. Lamina propria macrophages expressed both HLA-A, -B, -C and Ia-like antigens, the latter having strong membrane and cytoplasmic fluorescence. The distribution of T cells with suppressor-cytotoxic or inducer phenotype in the intestinal epithelium and lamina propria may be related to the differential expression of Ia-like and HLA-A, -B, -C antigens in intestinal mucosa.

Immunohistological characterisation of intraepithelial lymphocytes of the human gastrointestinal tract

Intraepithelial lymphocytes (IEL) of the normal human stomach, small intestine, and large intestine have been characterised in tissue sections by a double marker immunofluorescent technique. A panel of reagents was used in combination, including antisera to T lymphocyte antigen (HuTLA), Ia-like (p28, 33) antigens and immunoglobulin subclasses, as well as a mouse monoclonal antibody to a human leucocyte antigen (HLe-1). In stomach and proximal small intestine over 95% of IEL were T lymphocytes (HLe-1+, HuTLA+). The proportion was slightly lower in the colon and rectum (85--95%). IEL rarely expressed Ia-like antigens. B lymphocytes were not seen within the epithelium of any of the tissues examined. The functions of IEL must be assessed in the light of the finding that they are predominantly T cells.

Immunoglobulin containing cells in inflammatory bowel disease of the colon: a morphometric and immunohistochemical study

Immunoglobulin containing cells in rectal and sigmoid colonic mucosa in endoscopically obtained biopsies from 10 patients with ulcerative colitis and 10 patients with Crohn's disease were studied, using an indirect immunoperoxidase technique. These findings were compared with the immunoglobulin containing cell number in colonic biopsies from 10 control patients with no evidence of colitis. In biopsies from the 20 patients with inflammatory bowel disease a marked increase in area of the lamina propria per millimetre mucosa length was found. In ulcerative colitis a marked increase in number of IgG containing cells was observed. In Crohn's disease the increase in IgG containing cell number is dependent on the degree of activity of inflammation. In quiescent of active Crohn's disease of the colon we found a significant increase of the IgM containing cells. The number of IgM containing cells per millimetre mucosa length will differentiate the pathology of Crohn's disease from ulcerative colitis.

Lymphocyte subpopulations of intestinal mucosa in inflammatory bowel disease

Lymphocyte subpopulations in peripheral blood (PBL) and intestinal mucosa (IML) of 10 patients with inflammatory bowel disease (IBD) were compared with those of 11 non-IBD controls. PBL were separated on Ficoll/hypaque gradients, and IML were isolated by incubation in dithiothreitol, EDTA, and collagenase. These methods yielded cells of good viability and with intact HLA A and B-antigens. T-cells, identified by neuraminidase-treated sheep RBC rosettes and non-specific esterase staining, comprised approximately 91% of the IML from normal mucosa of all groups. B-cells, identified by erythrocyte-antibody-complement rosettes and surface immunoglobulins, were only 7% of these IML populations. Cell yields were two-fold or more greater from abnormal IBD mucosa, with T-cells ranging from 55 to 95% and B-cells from 2 to 36%. The percentage of Fc receptor bearing cells was low in all specimens. By these methods, T-lymphocytes predominated in intestinal mucosa of both IBD and non-IBD patients, but there is marked increase in the percentage of B-cells isolated from abnormal mucosa in IBD.

Peripheral blood and mesenteric lymph node lymphocytes in Crohn's disease

Analysis of peripheral blood lymphocytes from 44 patients with Crohn's disease showed no difference in the proportions of T- and B-cells from those in 38 healthy controls. Analysis revealed no disturbances in relation to duration or to activity of disease or to drug treatment. Lymphocytes from 18 patients with rheumatoid arthritis also showed normal proportions of T- and B-cells. Lymphocytes taken from gut lymph nodes were studied in five patients with Crohn's disease. On comparison with peripheral blood lymphocytes, significantly decreased proportions of T-cells and significantly increased proportions of B-cells were found in lymph nodes draining areas of diseased bowel. No differences were seen in the proportions of T- and B-cells from lymph nodes taken from apparently healthy bowel of the Crohn's patients and of four control subjects without inflammatory bowel disease, though these were different from those in the peripheral blood in both the Crohn's patients and control subjects.

[The immune competence of patients with Crohn's disease (author's transl)]

The cell-mediated and humoral immune responses were assessed in 15 patients with Crohn's disease and in 28 age-matched control subjects by means of several in vivo and in vitro methods. The disease activity in most patients was absent or moderate. Studying cellular immunocompetence we investigated the skin reactivity to various recall antigens (Candida, Trichophytin, Mumpsantigen, Streptokinase-Streptodornase, PPD), the primary immune response to Dinitrochlorobenzene (DNCB) and Keyhole Limpet Hemocyanin (KLH), and the lymphocyte transformation induced by mitogens (Phytohemagglutinin, Concanavaline A, Pokeweed Mitogen) and specific antigens. Humoral immunity was studied by measuring immunoglobulins, isohemagglutinins, and the antibody response to KLH. In addition, complement components and (in 10 patients) the proportions of T- and B-lymphocytes in the peripheral blood were evaluated. Cutaneous responsiveness to Candida, Mumps-antigen, SK-SD, and DNCB as well as the cellular immune response to KLH were impaired in patients with Crohn's disease (significance was reached for SK-SD, DNCB, and the mean area of induration). The lymphocyte transformation test with PHA, ConA, and PWM revealed normal results. For specific antigens (PPD, SK-SD, KLH) a good correlation could be demonstrated between delayed hypersensitivity and the in vitro lymphocyte responsiveness. Humoral immunity was not unequivocally impaired in Crohn's disease. Five patients with Crohn's disease proved constantly decreased total absolute lymphocyte counts in peripheral blood. The proportions of T- and B-lymphocytes and the complement-levels were corresponding to those in normal controls. No correlation was found between immunological and clinical parameters. In conclusion, patients with Crohn's disease exhibited a partial impairment of the cellular immune response, whereas humoral immunity was not affected. However, it remains to be elucidated whether this immune defect represents a basic pathogenetic factor in the onset of the disease.