Immunoglobulin G (IgG), IgG1, and IgG2 determinations from endoscopic biopsy specimens in control, Crohn's disease, and ulcerative colitis subjects

Immunoglobulin class-switch recombination: Mechanism, regulation, and related diseases

Maturation of the secondary antibody repertoire requires class-switch recombination (CSR), which switches IgM to other immunoglobulins (Igs), and somatic hypermutation, which promotes the production of high-affinity antibodies. Following immune response or infection within the body, activation of T cell-dependent and T cell-independent antigens triggers the activation of activation-induced cytidine deaminase, initiating the CSR process. CSR has the capacity to modify the functional properties of antibodies, thereby contributing to the adaptive immune response in the organism. Ig CSR defects, characterized by an abnormal relative frequency of Ig isotypes, represent a rare form of primary immunodeficiency. Elucidating the molecular basis of Ig diversification is essential for a better understanding of diseases related to Ig CSR defects and could provide clues for clinical diagnosis and therapeutic approaches. Here, we review the most recent insights on the diversification of five Ig isotypes and choose several classic diseases, including hyper-IgM syndrome, Waldenström macroglobulinemia, hyper-IgD syndrome, selective IgA deficiency, hyper-IgE syndrome, multiple myeloma, and Burkitt lymphoma, to illustrate the mechanism of Ig CSR deficiency. The investigation into the underlying mechanism of Ig CSR holds significant potential for the advancement of increasingly precise diagnostic and therapeutic approaches.

Redefining serological diagnostics with immunoaffinity proteomics

Serological diagnostics is generally defined as the detection of specific human immunoglobulins developed against viral, bacterial, or parasitic diseases. Serological tests facilitate the detection of past infections, evaluate immune status, and provide prognostic information. Serological assays were traditionally implemented as indirect immunoassays, and their design has not changed for decades. The advantages of straightforward setup and manufacturing, analytical sensitivity and specificity, affordability, and high-throughput measurements were accompanied by limitations such as semi-quantitative measurements, lack of universal reference standards, potential cross-reactivity, and challenges with multiplexing the complete panel of human immunoglobulin isotypes and subclasses. Redesign of conventional serological tests to include multiplex quantification of immunoglobulin isotypes and subclasses, utilize universal reference standards, and minimize cross-reactivity and non-specific binding will facilitate the development of assays with higher diagnostic specificity. Improved serological assays with higher diagnostic specificity will enable screenings of asymptomatic populations and may provide earlier detection of infectious diseases, autoimmune disorders, and cancer. In this review, we present the major clinical needs for serological diagnostics, overview conventional immunoassay detection techniques, present the emerging immunoassay detection technologies, and discuss in detail the advantages and limitations of mass spectrometry and immunoaffinity proteomics for serological diagnostics. Finally, we explore the design of novel immunoaffinity-proteomic assays to evaluate cell-mediated immunity and advance the sequencing of clinically relevant immunoglobulins.

Crohn's patients and healthy infants share immunodominant B cell response to commensal flagellin peptide epitopes

About half of patients with Crohn's disease (CD) develop selective serum IgG response to flagellin proteins of the Lachnospiraceae family. Here, we identified a dominant B cell peptide epitope in CD, locating in the highly conserved "hinge region" between the D0 and D1 domains at the amino-terminus of Lachnospiraceae flagellins. Serum IgG reactive to this epitope is present at an elevated level in adult CD patients and in pediatric CD patients at diagnosis. Most importantly, high levels of serum IgG to the hinge epitope were found in most infants from 3 different geographic regions (Uganda, Sweden, and the USA) at one year of age. This vigorous homeostatic response decrements with age as it is not present in healthy adults. These data identify a distinct subset of CD patients, united by a shared reactivity to this dominant flagellin epitope that may represent failure of a homeostatic response beginning in infancy.

ECCO Position on Harmonisation of Crohn's Disease Mucosal Histopathology

In inflammatory bowel disease [IBD], mucosal healing is a major therapeutic target and a reliable predictor of clinical course. However, endoscopic mucosal healing is not synonymous with histological healing, and the additional benefits of including histological remission as a target are unclear. In Crohn´s disease [CD], there are few studies highlighting the value of histological remission as a therapeutic target. Histological activity can persist in CD patients who are in endoscopic remission, and the absence of histological activity may be associated with lower relapse rates. Therefore, standardisation of procedures to evaluate CD histological activity is desirable. Topics that would benefit from standardisation and harmonisation include biopsy procedures, biopsy processing techniques, the content of histological scores, and the definitions of histological remission, histological response, and histological activity. In line with these needs, the European Crohn's and Colitis Organisation [ECCO] assembled a consensus group with the objective of developing position statements on CD histology based on published evidence and expert consensus. There was agreement that definitions of histological remission should include absence of erosion, ulceration, and mucosal neutrophils; that the absence of neutrophilic inflammation is an appropriate histological target in CD; that CD histological scores, such as the Global Histological Disease Activity Score, lack formal validation; and that histological scoring systems for ulcerative colitis, including the Geboes Score, Robarts Histopathology Index, and Nancy Histological Index, can be used for scoring intestinal biopsies in CD patients.

B cell class switching in intestinal immunity in health and disease

The gastrointestinal tract is colonized by trillions of commensal microorganisms that collectively form the microbiome and make essential contributions to organism homeostasis. The intestinal immune system must tolerate these beneficial commensals, whilst preventing pathogenic organisms from systemic spread. Humoral immunity plays a key role in this process, with large quantities of immunoglobulin (Ig)A secreted into the lumen on a daily basis, regulating the microbiome and preventing bacteria from encroaching on the epithelium. However, there is an increasing appreciation of the role of IgG antibodies in intestinal immunity, including beneficial effects in neonatal immune development, pathogen and tumour resistance, but also of pathological effects in driving chronic inflammation in inflammatory bowel disease (IBD). These antibody isotypes differ in effector function, with IgG exhibiting more proinflammatory capabilities compared with IgA. Therefore, the process that leads to the generation of different antibody isotypes, class-switch recombination (CSR), requires careful regulation and is orchestrated by the immunological cues generated by the prevalent local challenge. In general, an initiating signal such as CD40 ligation on B cells leads to the induction of activation-induced cytidine deaminase (AID), but a second cytokine-mediated signal determines which Ig heavy chain is expressed. Whilst the cytokines driving intestinal IgA responses are well-studied, there is less clarity on how IgG responses are generated in the intestine, and how these cues might become dysfunctional in IBD. Here, we review the key mechanisms regulating class switching to IgA vs IgG in the intestine, processes that could be therapeutically manipulated in infection and IBD.

Mucosal IgG in inflammatory bowel disease - a question of (sub)class?

Immunoglobulins (Igs) form a cornerstone of mucosal immunity. In the gastrointestinal tract, secretory IgA and IgM bind to commensal microorganisms within the intestinal lumen to prevent them from breaching the intestinal epithelium - a process known as immune exclusion. In recent years, there has been renewed interest in the role of IgG in intestinal immunity, driven in part by a genetic association of an affinity-lowering variant of an IgG receptor, FcγRIIA, with protection from ulcerative colitis (UC), a subclass of inflammatory bowel disease (IBD). We recently demonstrated a role for IgG and Fcγ receptor signalling in driving pathogenic IL-1β production by colonic mononuclear phagocytes and the subsequent induction of a local type 17 response in UC. Here, we discuss the potential relevance of our observations to the other major subclass of IBD - Crohn's disease (CD) - where the genetic association with FCGR variants is less robust and consider how this may impact therapeutic interventions in these disease subsets.

Distinct patterns of naive, activated and memory T and B cells in blood of patients with ulcerative colitis or Crohn's disease

Both major subcategories of inflammatory bowel disease (IBD), ulcerative colitis and Crohn’s disease are characterized by infiltration of the gut wall by inflammatory effector cells and elevated biomarkers of inflammation in blood and feces. We investigated the phenotypes of circulating lymphocytes in the two types of IBD in treatment‐naive pediatric patients by analysis of blood samples by flow cytometry. Multivariate analysis was used to compare the phenotypes of the blood lymphocytes of children with ulcerative colitis (n = 17) or Crohn’s disease (n = 8) and non‐IBD control children with gastrointestinal symptoms, but no signs of gut inflammation (n = 23). The two IBD subcategories could be distinguished based on the results from the flow cytometry panel. Ulcerative colitis was characterized by activated T cells, primarily in the CD8⁺ population, as judged by increased expression of human leukocyte antigen D‐related (HLA‐DR) and the β1‐integrins [very late antigen (VLA)] and a reduced proportion of naive (CD62L⁺) T cells, compared with the non‐IBD controls. This T cell activation correlated positively with fecal and blood biomarkers of inflammation. In contrast, the patients with Crohn’s disease were characterized by a reduced proportion of B cells of the memory CD27⁺ phenotype compared to the non‐IBD controls. Both the patients with ulcerative colitis and those with Crohn’s disease showed increased percentages of CD23⁺ B cells, which we demonstrate here as being naive B cells. The results support the notion that the two major forms of IBD may partially have different pathogenic mechanisms.

Anti-food and anti-microbial IgG subclass antibodies in inflammatory bowel disease

OBJECTIVES

Inflammatory bowel disease (IBD), particularly Crohn's disease (CD), is associated with increased microbial-specific IgG and IgA antibodies, whereas alterations of anti-food antibodies are still disputed. The knowledge about IgG subclass antibodies in IBD is limited. In this study we analysed IgG subclass antibodies specific for nutritional and commensal antigens in IBD patients and controls.

METHODS

Serum IgG1, IgG2, IgG3 and IgG4 specific for wheat and milk extracts, purified ovalbumin, Escherichia coli and Bacteroides fragilis lysates and mannan from Saccharomyces cerevisiae were analysed by ELISA in patients with CD (n = 56), ulcerative colitis (UC; n = 29), acute gastroenteritis/colitis (n = 12) as well as non-inflammatory controls (n = 62).

RESULTS

Anti-Saccharomyces cerevisiae antibodies (ASCA) of all IgG subclasses and anti-B. fragilis IgG1 levels were increased in CD patients compared to UC patients and controls. The discriminant validity of ASCA IgG2 and IgG4 was comparable with that of ASCA pan-IgG and IgA, whereas it was inferior for ASCA IgG1/IgG3 and anti-B. fragilis IgG1. Complicated CD defined by the presence of perianal, stricturing or penetrating disease phenotypes was associated with increased ASCA IgG1/IgG3/IgG4, anti-B. fragilis IgG1 and anti-E. coli IgG1 levels. Anti-food IgG subclass levels were not different between IBD patients and controls and did not correlate with food intolerance. In contrast to anti-microbial Abs, food-specific IgG responses were predominately of the IgG4 isotype and all food-specific IgG subclass levels correlated negatively with age.

CONCLUSION

Our study supports the notion that the adaptive immune recognition of food and commensal antigens are differentially regulated.

B1a lymphocytes in ulcerative colitis

BACKGROUND AND AIMS

B1a lymphocytes (CD5+) are the major contributors of natural antibodies (Ab) implicated in the initial protection against several infections. The aim of this study was to assess the expression of these cells in the peripheral blood of ulcerative colitis (UC) patients who underwent restorative proctocolectomy (RPC) and others who were not operated on.

MATERIALS AND METHODS

The blood concentration of CD5+ B cells was analysed by three-colour flow cytometry. Blood was collected from 38 UC patients, 20 of whom had undergone RPC and compared with the results in 18 healthy controls and in 12 familial adenomatous polyposis (FAP) patients who had undergone RPC. We were interested in evaluating if there was any correlation between B1a blood cell concentration and ESR and CRP levels, clinical, endoscopic and histological activity, perinuclear anti-neutrophil cytoplasmic antibody (pANCA) and extra-intestinal symptoms.

RESULTS

B1a cell blood concentration was reduced in non-operated UC patients (20.7 +/- 4.6/microl) with respect to that in healthy controls (71.1 +/- 18.0/microl, p < 0.05). It was also lower in UC patients with RPC (24.9 +/- 1.0/microl) compared to RPC for FAP (48.2 +/- 6.2, p < 0.05). B1a cell rate correlated inversely in UC patients with ESR (R = -0.41, p < 0.05) and CRP levels (R = -0.47, p = 0.01).

CONCLUSION

B1a cell concentration was reduced in the blood of patients with UC even after the diseased organ was surgically removed by proctocolectomy. As these cells play an important role in natural immunity against luminal stimuli, consistently lower levels that are found in UC patients could be responsible for the impaired immunologic response to gut antigens in this disease.

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.

Distal proctocolitis and n-3 polyunsaturated fatty acids (n-3 PUFAs): the mucosal effect in situ

It has been postulated that patients with ulcerative colitis (UC) have altered reactivity of gut-associated lymphoid tissue. In such cases there is intense infiltration of the mucosa with immune competent cells and associated tissue damage. We have shown previously that the dietary supplementation with the n-3 polyunsaturated fatty acids (n-3 PUFAs), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) results in significant systemic immune suppression. The aim of this study, therefore, was to evaluate the in situ effect of n-3 PUFAs on distal proctocolitis. Each patient received either fish oil extract (EPA 3.2 g, DHA 2.4 g) (n = 9) or sunflower oil (n = 9) daily in a double blind manner for six months. Monthly assessment included: (1) disease activity using clinical, sigmoidoscopic, and histological scores and (2) immunohistochemical analysis (immunoglobulins, CD profiles) of rectal biopsy specimens (before and after six months supplementation) using monoclonal antibodies and quantitative computer-assisted video image analysis. Prior to receiving supplementation, patients with proctocolitis (n = 18) showed significantly higher numbers of cells expressing CD3 (pan T cells) and HLA-DR and IgM containing cells compared with non-colitic controls (n = 8). Six months supplementation with n-3 PUFAs resulted in significant reduction in the number of cells expressing CD3 and HLA and the percentage of cells containing IgM. There was no significant change in the CD20 nor the percentage of IgG or IgA containing cells in either group of patients with procto-colitis. In patients receiving n-3 PUFA supplementation, there was improvement in the disease activity and histological scores, compared with pretreatment evaluation. This study has demonstrated both evidence of suppression of in situ immune reactivity and concurrent reduction in disease activity in patients with proctocolitis receiving n-3 PUFA supplementation. This may have important implication for therapy in patients with ulcerative colitis.

Developmental regulation of immunoglobulin mRNA processing and the IgA response: establishing a paradigm

IgA, which is protective at mucosal sites, is derived from memory B cells that develop in the organized lymphoid tissue of the gastrointestinal tract and subsequently mature to plasma cells in the lamina propria. Similarly to B cells expressing other isotypes, the maturation of IgA-expressing B cells is associated with both an increase in the steady-state level of immunoglobulin mRNA and the ratio of secreted to membrane forms of mRNA, which differ in 3' terminus. In contrast to B cells expressing other isotypes, at all stages in the development of an IgA response, the secreted form of alpha mRNA predominates. In this article, studies on the general features of IgA B cell development, mechanisms regulating 3' terminus usage of Ig mRNAs, and isotype-specific regulation of 3' terminus usage particularly in regard to alpha mRNA are discussed.

Antiinflammatory effects of enterically coated amoxicillin-clavulanic acid in active ulcerative colitis

The inflammatory activity of colonic mucosal lesions may be stimulated by intraluminal bacteria. Our aim was to investigate whether administration of broad-spectrum antibiotics decreases inflammatory activity in ulcerative colitis. To this end, we performed a randomized, 5-day study with either oral enterically coated amoxicillin-clavulanic acid (1 g + 250 mg, t.i.d.); i.v. methylprednisolone (40 mg/day) and oral placebo (t.i.d.); or both i.v. methylprednisolone and oral amoxicillin-clavulanic acid as above, in 30 patients with clinically active ulcerative colitis. Before and after 5 days of treatment, intestinal inflammation was assessed by the quantification of mucosal release of eicosanoids and interleukin-8 by rectal dialysis in each patient. Breath H2 excretion after oral lactulose was determined as an index of metabolic activity of colonic flora. The total release of (IL-8) interleukin-8 and eicosanoids significantly decreased in patients treated with antibiotic or steroids and antibiotic. Antibiotic treatment, but not steroids, markedly inhibited breath H2 excretion. In conclusion, short-term treatment with enteric-coated amoxicillin-clavulanic acid decreases the intraluminal release of IL-8 and other inflammatory mediators.

Immunoglobulin G subclass distribution of anti-endothelial cell antibodies (AECA) in patients with ulcerative colitis or Crohn's disease

Anti-endothelial cell antibodies have been described in sera from patients with inflammatory bowel disease. The aim of this study was to determine, by ELISA, the IgG subclass distribution of anti-endothelial cell antibodies, in patients with ulcerative colitis (N = 28) or Crohn's disease (N = 82) as compared with blood donors (N = 95). Thirty-six percent of ulcerative colitis and 23% of Crohn's disease patients were positive for at least one of the IgG anti-endothelial cell subclasses. Interestingly, the pattern of IgG anti-endothelial cell subclass observed in the two inflammatory bowel diseases differs. In Crohn's disease, the IgG1 anti-endothelial cell antibody level was significantly increased (P < 0.05) while IgG2 and IgG4 anti-endothelial cell antibody levels were decreased (P < 0.0001 and P < 0.01, respectively) as compared to ulcerative colitis patients. The immunoglobulin G3 anti-endothelial cell antibody level was decreased in both ulcerative colitis and Crohn's disease patients as compared to healthy blood donors. No relationship was detected between disease activity of ulcerative colitis or Crohn's disease patients and anti-endothelial cell IgG subclasses. Finally, the disparity of IgG anti-endothelial cell subclass distribution in these two inflammatory bowel diseases suggests that the ability to activate effector mechanisms is not identical, and hence, deals with the concept of distinctive pathogenetic mechanisms in these two diseases.

Mucosal antibodies in inflammatory bowel disease are directed against intestinal bacteria

In contrast with normal subjects where IgA is the main immunoglobulin in the intestine, patients with active inflammatory bowel disease (IBD) produce high concentrations of IgG from intestinal lymphocytes, but the antigens at which these antibodies are directed are unknown. To investigate the specificities of these antibodies mucosal immunoglobulins were isolated from washings taken at endoscopy from 21 control patients with irritable bowel syndrome, 10 control patients with intestinal inflammation due to infection or ischaemia, and 51 patients with IBD: 24 Crohn's disease (CD, 15 active, nine quiescent), 27 ulcerative colitis (UC, 20 active, seven inactive). Total mucosal IgG was much higher (p < 0.001) in active UC (median 512 micrograms/ml) and active CD (256 micrograms/ml) than in irritable bowel syndrome controls (1.43 micrograms/ml), but not significantly different from controls with non-IBD intestinal inflammation (224 micrograms/ml). Mucosal IgG bound to proteins of a range of non-pathogenic commensal faecal bacteria in active CD; this was higher than in UC (p < 0.01); and both were significantly greater than controls with non-IBD intestinal inflammation (CD p < 0.001, UC p < 0.01) or IBS (p < 0.001 CD and UC). This mucosal IgG binding was shown on western blots and by enzyme linked immunosorbent assay (ELISA) to be principally directed against the bacterial cytoplasmic rather than the membrane proteins. Total mucosal IgA concentrations did not differ between IBD and controls, but the IgA titres against faecal bacteria were lower in UC than controls (p < 0.01). These experiments show that there is an exaggerated mucosal immune response particularly in active CD but also in UC directed against cytoplasmic proteins of bacteria within the intestinal lumen; this implies that in relapse of IBD there is a breakdown of tolerance to the normal commensal flora of the gut.

Production of immunoglobulin G and G1 antibodies to cytoskeletal protein by lamina propria cells in ulcerative colitis

BACKGROUND & AIMS

Recent studies suggest an autoantigenic role for tropomyosin-related protein(s) in ulcerative colitis (UC). This study examined whether immunoglobulin G and G1 subclass antibodies against tropomyosins are produced spontaneously by the lamina propria mononuclear cells (LPMCs) that infiltrate the inflamed UC tissue.

METHODS

LPMCs were isolated from colonic biopsy specimens from 29 patients with UC, 15 with colonic Crohn's disease (CD), and 13 with non-inflammatory bowel disease (IBD). The autologous peripheral blood mononuclear cells (PBMCs) were obtained. Cells were cultured in vitro and unstimulated for 10 days. Spontaneous production of immunoglobulin G and G1 antibodies against tropomyosins was measured by enzyme-linked immunosorbent assays using highly enriched tropomyosins from skeletal muscle and colonic mucosa.

RESULTS

The total immunoglobulin G produced by LPMCs from both patients with UC and CD was comparable but higher than from patients with non-IBD (P < 0.05). However, immunoglobulin G antibodies to tropomyosins were higher in patients with UC than in patients with CD (P < 0.04) and non-IBD (P < 0.02). LPMCs from patients with symptomatic UC produced higher immunoglobulin G antibodies to tropomyosins than patients with UC in remission (P < 0.03), symptomatic CD (P < 0.04), and non-IBD (P < 0.02). Immunoglobulin G antibodies to tropomyosins predominantly belonged to immunoglobulin G1 subclass. The autologous PBMCs showed comparable results.

CONCLUSIONS

Immunoglobulin G antibodies predominantly belonging to immunoglobulin G1 subclass and reactive against tropomyosin-related protein(s) are spontaneously produced by LPMCs from the colonic mucosa in patients with UC.

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.

Immunoglobulin G subclass distribution of human anticolon antibodies in ulcerative colitis

Immunoglobulin G (IgG) subclasses of anticolon antibodies were studied in patients with ulcerative colitis (UC) using enzyme-linked immunosorbent assay (ELISA). The concentrations of total serum IgG subclasses were also measured by ELISA. The values for total serum IgG subclasses in patients with UC were not significantly different from those in normal controls, while the ratio of IgG1 to IgG2 in the patients was significantly higher than that in normal controls. All four IgG subclasses of autoantibodies were demonstrated in the sera of the patients. IgG4 anticolon antibodies were detected most frequently (15 out of 18 patients, 83%). IgG2 was the next most prevalent (9 of 18 patients, 50%). The activity of anticolon antibodies in each subclass did not correlate with the concentration of the corresponding serum IgG subclass. Seven cell lines producing anticolon antibodies were obtained from the colonic mucosa of the patients by Epstein-Barr virus (EBV) transformation. IgG subclasses of anticolon antibodies secreted by these cell lines were also varied. IgG4 subclass was secreted by three EBV transformed cell lines, all of which produced IgG4 anticolon antibodies. These results suggest that all four different IgG subclasses could respond to the colon antigens and that various antigens in colonic mucosa or lumen may contribute to the induction of those autoantibodies. In addition, the prominence of IgG4 anticolon antibodies may support the pathogenic role of this subclass in UC as in other autoimmune diseases.

Treatment of active distal ulcerative colitis with immunoglobulin G enemas

Seven patients with active distal ulcerative colitis were treated with IgG enemas given as a daily bedtime retention enema for two weeks. Evaluation of effect was assessed by means of sigmoidoscopy with biopsy, measuring acute phase reactants in peripheral blood, and measuring the faecal protein loss. Clinical signs of active disease were registered by the patients on a diary chart. Five patients completed the treatment period, two patients were withdrawn after 7 and 10 days due to deterioration of disease. Four patients did not register any effect, whereas one patient improved clinically. In conclusion, rectally administered IgG did not exert any effect on rectal ulcerative colitis in our study.