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Background: Patients with Crohn's disease (CD) are at risk of complications. Performance characteristics of a decision support tool assessing the risk of CD complications were evaluated., Methods: CDPATH (formerly called the Personalized Risk and Outcome Prediction Tool [PROSPECT]) was calibrated and validated in 2 cohorts. Tool prediction of disease characteristics was assessed using Cox regression and Harrell's C -statistic., Results: All associations of CD complications and CDPATH components were significant except perianal location. There was a significant association between individualized risk assessment scores and CD complications in both cohorts., Conclusion: CDPATH is validated as a clinical decision support tool for assessing the risk of CD complications., (© The Author(s) 2021. Published by Oxford University Press on behalf of Crohn\'s & Colitis Foundation.)

Background: Crohn disease (CD) affects the small bowel in 80% of patients. Double balloon endoscopy (DBE) provides the potential for direct and extensive mucosal visualization with the potential for diagnostic monitoring and therapeutic intervention. This study aimed to investigate the safety and effectiveness of DBE in small-bowel CD., Methods: From our DBE database, patients with CD at the time of index DBE (January 2004-January 2013) were identified. Data collection included demographics, CD phenotype (age at diagnosis, disease location, disease activity), procedural information, adverse events (perforation, pancreatitis, death), therapeutic intervention (stricture dilation), and outcome (escalation or maintenance of existing therapy, referral to surgery)., Results: A total of 184 DBEs were performed in patients with inflammatory bowel disease over 162 endoscopic sessions. In this cohort, 115 patients had previously diagnosed CD. A diagnosis of CD was made in 22 patients. Of those with known CD, 140 DBEs were performed in 82 patients; DBE findings led to escalation of medical therapy in 26% of patients, maintenance of therapy in 26% of patients, and surgery in 18% of patients. We considered DBE to have failed in 11% (n = 18) of patients. During 46 endoscopic sessions, in 29 patients, 103 strictures were dilated via balloon dilation. Of patients undergoing dilation with clinical follow-up, 19 of 24 (79%) patients were surgery-free during the study period. Overall, there were 2 perforations., Conclusions: We found that DBE is a safe and effective procedure in patients with suspected or established CD. Furthermore, patients undergoing dilation of strictures via DBE had an 80% surgery-free rate within the follow-up period., (© 2020 Crohn’s & Colitis Foundation. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: This study reports on the logistics and feasibility of a novel multidisciplinary approach to biopsychosocial care at a tertiary adult inflammatory bowel disease (IBD) center., Methods: Consecutive patients referred for a new IBD consultation completed the following self-assessments: the Short Form-12, the Patient Reported Outcome Measurement Information System (PROMIS) Global Health Scale, the World Health Organization Disability Assessment Schedule 2.0, and the PROMIS-29. These measures were scored at the time of appointment check-in by a trained licensed clinical social worker (SW), and those scoring 1.5 standard deviations below the population mean were targeted for SW assessment and intervention at the point of care; patients or providers could also request a SW evaluation even if cutoffs were not met. In this stepped-care model, the SW could refer to same-day on-site psychiatry services or outside interventions and services. In addition, we implemented a 12-month curriculum with a monthly didactic and case-based education seminar for health care providers who interact with patients with IBD., Results: Between February 2014 and May 2015, 110 patients (53% male; mean age, 42 years) completed a self-assessment. All patients completed their self-assessment within 10 minutes. Of these, 36.4% (40/110) were targeted for SW assessment and intervention. The SW interventions were grouped into 4 categories: psychological education and coping tools for symptom management and emotional wellness (n = 30); psychotherapy referrals (n = 30); financial/governmental programs (n = 11); and psychiatry referrals for consultation and/or medication prescription (n = 21). The educational seminars were highly rated by participating providers., Conclusions: A multidisciplinary biopsychosocial approach to adult IBD care is feasible. Education for providers and close coordination across specialties are critical to the success of a multidisciplinary biopsychosocial program.

Background and Aims: We assessed the effect of ustekinumab on health-related quality of life [HRQOL] in adults with Crohn's disease [CD]., Methods: Patients with moderately to severely active CD and inadequate response or intolerance to tumour necrosis factor antagonists [UNITI-1, n = 741], or conventional therapy [UNITI-2, n = 627] were randomised to placebo, ustekinumab 130 mg, or 6 mg/kg intravenous induction therapy. At Week 8, ustekinumab-treated responders (Crohn's Disease Activity Index [CDAI] reduction ≥100 or CDAI <150 points) were re-randomised to subcutaneous maintenance therapy [IM-UNITI, n = 388] with placebo, ustekinumab 90 mg every 12 weeks [q12w], or ustekinumab 90 mg every 8 weeks [q8w], for 44 additional weeks. Inflammatory Bowel Disease Questionnaire [IBDQ] and 36-item Short Form Health Survey [SF-36] physical component summary [PCS] and mental component summary [MCS] scores were completed at induction baseline and Week 8, and at maintenance Weeks 20 and 44. Clinically meaningful improvement in IBDQ and PCS and MCS scores were evaluated. For all HRQOL outcomes, each ustekinumab dose and placebo were compared., Results: Induction baseline mean values of IBDQ, PCS, and MCS were similar across groups, but impaired relative to general population norms. At Week 8, ustekinumab induced greater improvement than placebo in both HRQOL scores. Significantly greater proportions of patients receiving ustekinumab 6 mg/kg or 130 mg had clinically meaningful IBDQ improvement [UNITI-1: 54.8%, 46.9% versus 36.5%, respectively; UNITI-2: 68.1%, 58.7% versus 41.1%, respectively; p <0.05, all comparisons]. Similarly, greater proportions of ustekinumab-treated patients in both studies had clinically meaningful improvements in PCS and MCS as compared with placebo. At Week 44, improvements in IBDQ, PCS, and MCS scores were maintained with ustekinumab., Conclusions: Ustekinumab improved HRQOL in patients with moderately to severely active CD.

Background and Aims: A subset of patients who undergo ileal pouch-anal anastomosis [IPAA] for ulcerative colitis [UC] will later be diagnosed with denovo Crohn's disease [CD]. These patients have a higher risk of pouch failure. In this study we evaluated inflammatory bowel disease [IBD] serology in patients with denovo CD and examined the success of anti-tumour necrosis factor-alpha [anti-TNFα] therapy in preventing ileostomy in denovo CD patients who failed anti-TNFα therapy before IPAA., Methods: A prospectively maintained database of patients undergoing IPAA was reviewed to identify patients who developed denovo CD [defined as small bowel inflammation above the pouch inlet or pouch fistula/perianal disease appearing more than 3 months after stoma closure]. Clinical characteristics and IBD serology were analysed. Treatment failure was defined as pouch failure requiring ileostomy or pouchectomy., Results: Of 350 patients included in the study, 92 [26%] patients developed denovo CD. Significantly more denovo CD patients had anti-I2 positivity postoperatively versus preoperatively [p = 0.007]. Anti-TNFα therapy successfully treated denovo CD in 28 out of 38 [74%] patients. Out of 17 patients with denovo CD who had failed to respond to anti-TNFα agents before surgery and were treated with anti-TNFα therapy after surgery, 12 [71%] patients responded to treatment., Conclusions: I2 serology may possibly help identify patients who have developed or are at risk for developing denovo CD. Anti-TNFα therapy for denovo CD after IPAA can help prevent permanent ileostomy in almost 75% of cases, even in patients who previously failed anti-TNFα treatment before surgery., (Copyright © 2016 European Crohn’s and Colitis Organisation (ECCO). Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: Denovo Crohn's disease (CD) develops in 5% to 10% of patients after ileal pouch-anal anastomosis (IPAA) for ulcerative colitis (UC) leading to increased morbidity and rates of pouch failure. Initial nonbloody diarrhea and weight loss at diagnosis are independent risk factors for a change in diagnosis from UC to CD in nonsurgical patients. We investigated whether these features were risk factors for denovo CD in a longitudinal cohort of patients with UC undergoing IPAA., Methods: Prospective profiles of patients with UC undergoing IPAA followed over a 22-year period by 1 surgeon were analyzed. Denovo CD was diagnosed when mucosal inflammation (5 or more ulcers) involved the small bowel mucosa proximal to the ileal pouch any time after surgery and/or when a pouch fistula or other perianal complication developed more than 3 months after ileostomy closure. Patients with inflammatory bowel disease unclassified, acute pouchitis, chronic pouchitis, and those lost to follow-up were excluded from analysis. Cox regression analysis was performed for statistical significance., Results: Of the 199 study patients included in the analysis, denovo CD developed in 42 patients (21%). Patients who developed denovo CD had an increased incidence of nonbloody diarrhea (n = 12; 29%) compared with patients who had no evidence of pouch inflammation (n = 25; 16%) (P = 0.03). In contrast, the incidence of weight loss was not significantly increased in patients with denovo CD (n = 7; 17%) compared with patients who never had pouch inflammation (n = 16; 10%) (P = 0.12)., Conclusions: Initial nonbloody diarrhea is associated with denovo CD after IPAA. This association warrants close consideration before surgery.

Background: PDA-001 (cenplacel-L), a preparation of placenta-derived mesenchymal-like adherent cells with immunomodulatory effects, previously demonstrated safety and tolerability in an open-label Crohn's disease (CD) study. The current phase 1b/2a study evaluated the safety and efficacy of PDA-001 in subjects with moderate-to-severe CD., Methods: Subjects had active inflammation on colonoscopy or elevated fecal calprotectin and inadequate response to conventional therapy. Concomitant therapy with stable doses of immunomodulators and/or biologics was permitted. Subjects received 8 units of PDA-001 (1.5 × 10 cells per unit) in the phase 1b open-label study. In the phase 2a double-blind study, subjects were randomly assigned placebo, 1 unit, or 4 units of PDA-001 (2 infusions 1 wk apart). The primary endpoint was induction of clinical response (≥100 points and/or 25% decrease in Crohn's Disease Activity Index) at 4 and 6 weeks., Results: Fifty subjects were enrolled (safety analysis, 50 subjects; efficacy analysis, 48 subjects). Four subjects received 8 units of PDA-001 (phase 1b study); 46 subjects were subsequently randomized to 1 or 4 units of PDA-001 or placebo (phase 2a study). The primary endpoint was achieved in 10/28 (36%) of PDA-001 subjects compared with placebo (0%, P = 0.026). Clinical remission was achieved in 4/28 (14%) of PDA-001 subjects compared with placebo (0%, P = 0.3). One treatment-related serious adverse event occurred (systemic hypersensitivity reaction at 8 units). In the phase 2a study, serious adverse events occurred in 9/28 (32%) of PDA-001 subjects and 1/16 (7%) of placebo subjects., Conclusions: A 2-infusion regimen of PDA-001 induced clinical response in subjects with moderate-to-severe CD. Additional studies are warranted.

Background: As a T cell-mediated disease of the colonic epithelium, ulcerative colitis (UC) is likely to share pathogenic elements with other T cell-mediated inflammatory diseases. Recently, microarray analysis revealed large-scale molecular changes in T cell-mediated rejection of kidney and heart transplants. We hypothesized that similar disturbances might be operating in UC and could provide insights into responsiveness to therapy., Methods: We studied 56 colon biopsies from patients with colitis characterizing the clinical and histological features and using microarrays to define the messenger RNA phenotype. We expressed the microarray results using previously defined pathogenesis-based transcript sets. We also studied 48 published microarray files from human colon biopsies downloaded from the Gene Expression Omnibus database, classified by response to infliximab therapy, to examine whether the molecular measurements derived from our studies correlated with nonresponsiveness to treatment., Results: UC biopsies manifested coordinate transcript changes resembling rejecting transplants, with effector T cell, IFNG-induced, macrophage, and injury transcripts increasing while parenchymal transcripts decreased. The disturbance in gene expression, summarized as principal component 1 (PC1), correlated with conventional clinical and histologic assessments. When assessed in microarray results from published studies, the disturbance (PC1) predicted response to infliximab: patients with intense disturbance did not achieve clinical response, although quantitative improvement was seen even in many clinical nonresponders. Similar changes were seen in Crohn's colitis., Conclusions: The molecular phenotype of UC manifests a large-scale coordinate disturbance reflecting changes in inflammatory cells and parenchymal elements that correlates with conventional features and predicts response to infliximab.

Background: Crohn's disease (CD) is considered a contraindication to ileal pouch--anal anastomosis (IPAA). In this study, we compare outcomes of CD and ulcerative colitis (UC) patients undergoing IPAA., Methods: Patients were considered to have CD before surgery based on a history of small bowel disease, perianal disease, noncrypt-associated granuloma, or pretreatment skip colonic lesions. Patients were prospectively assessed for pouchitis or CD. Postoperative CD (pouch inflammation into the afferent limb or pouch fistula) or pouch failure (need for permanent diversion) were assessed. Preoperative serum was assayed for IBD-associated antibodies using enzyme-linked immunosorbent assay (ELISA)., Results: Seventeen patients with preoperative CD were identified. Seven (41%) patients developed postoperative recurrent CD in the afferent limb (n = 3) or pouch fistulizing disease (n = 4). One patient (6%) required pouch excision. The incidence of postoperative CD was higher (P = 0.002) in preoperative CD patients (41%) than UC patients (11%). There was no significant difference in pouchitis or pouch failure. There was also no significant difference in any preoperative clinical feature between patients with or without postoperative CD. Afferent limb inflammation developed in three (50%) of the six patients with pANCA+/OmpC- expression compared to none of the 11 patients without this serologic profile (P = 0.03)., Conclusions: Although the intentional use of IPAA in CD has a higher incidence of postoperative disease vs. UC patients, there was no significant difference in pouch failure. Demographics, clinical features, and serologic factors do not predict outcome of CD patients undergoing IPAA. IBD serology may identify the phenotype manifestation of postoperative recurrent CD.

Background: Crohn's disease (CD) is often associated with antibodies to microbial antigens. Differences in immune response may offer clues to the pathogenesis of the disease. The aim was to examine the influence of age at diagnosis on the serologic response in children with CD., Methods: Data were drawn from 3 North American multicenter pediatric inflammatory bowel disease (IBD) research consortia. At or shortly after diagnosis, pANCA, ASCA IgA, ASCA IgG, anti-ompC, and anti-CBir1 were assayed. The results were compared as a function of age at CD diagnosis (0-7 years versus 8-15 years)., Results: In all, 705 children (79 <8 years of age at diagnosis, 626 >or=8 years) were studied. Small bowel CD was less frequent in the younger group (48.7% versus 72.6%; P < 0.0001), while colonic involvement was comparable (91.0% versus 86.5%). ASCA IgA and IgG were seen in <20% of those 0-7 years old compared to nearly 40% of those 8-15 years old (P < 0.001), while anti-CBir1 was more frequent in the younger children (66% versus 54%, P < 0.05). Anti-CBir1 detected a significant number of children in both age groups who otherwise were serologically negative. Both age at diagnosis and site of CD involvement were independently associated with expression of ASCA and anti-CBir1., Conclusions: Compared to children 8-15 years of age at diagnosis, those 0-7 years are more likely to express anti-CBir1 but only half as likely to express ASCA. These age-associated differences in antimicrobial seropositivity suggest that there may be different, and as yet unrecognized, genetic, immunologic, and/or microbial factors leading to CD in the youngest children.

The inflammatory bowel diseases (IBD) are comprised of two major phenotypes, Crohn's disease (CD) and ulcerative colitis (UC). Research over the last couple of years has led to great advances in understanding the inflammatory bowel diseases and their underlying pathophysiologic mechanisms. From the current understanding, it is likely that chronic inflammation in IBD is due to aggressive cellular immune responses to a subset of luminal bacteria. Susceptibility to disease is thereby determined by genes encoding immune responses which are triggered by environmental stimuli. Based on extensive research over the last decade, there are several new and novel pathways and specific targets on which to focus new therapeutics. The following review summarizes the current view on the four basic tenets of the pathophysiological basis of IBD and its implications for therapies of IBD: genetics, immune dysregulation, barrier dysfunction and the role of the microbial flora.

Background: The sensitivity of assays for antineutrophil cytoplasmic antibody (ANCA), anti-Saccharomyces cerevisiae antibody (ASCA), and antipancreatic antibody (PAB) in different laboratories is unknown. Likewise, the sensitivity and diagnostic usefulness of these assays in patients with inflammatory bowel disease (IBD) in the community is unknown., Methods: An incidence cohort of 290 patients with IBD were offered participation in the study. Blood was obtained from 162 patients (56%) (83 with ulcerative colitis, 79 with Crohn's disease) who agreed to participate. ANCA was determined in five laboratories. ASCA in two laboratories, and PAB in one laboratory., Results: In ulcerative colitis, the sensitivity of ANCA determined in five laboratories varied widely, ranging from 0-63%. In Crohn's disease, the sensitivity of ASCA determined in two laboratories did not vary significantly, ranging from 39-44%; and the sensitivity of PAB determined in one laboratory was 15%. The optimal diagnostic usefulness was obtained from one laboratory where the positive predictive values of a positive ANCA assay combined with a negative ASCA assay for ulcerative colitis, and a negative ANCA combined with a positive ASCA for Crohn's disease, were 75% and 86%, respectively., Conclusions: In patients with IBD, the sensitivity of ANCA varied widely in different laboratories, whereas the prevalence of ASCA was similar. The positive predictive values of the ANCA assay combined with the ASCA assay for ulcerative colitis and Crohn's disease are high enough to be clinically useful.

Background and Aims: A substantial number of patients with inflammatory bowel disease (IBD) fail to achieve a complete clinical response with 6-mercaptopurine (6-MP) and azathioprine (AZA). Inability to achieve therapeutic 6-thioguanine nucleotide (6-TGN) levels due to the preferential overproduction of 6-methylmercaptopurine ribonucleotides (6-MMPR) upon dose escalation characterizes a newly described subgroup of IBD patients resistant to 6-MP/AZA therapy. Treatment with 6-thioguanine (6-TG), a related thiopurine, which forms 6-TGNs more directly may be beneficial in such patients. This pilot study evaluated the safety, tolerance, and efficacy of 6-TG in the subgroup of Crohn's disease (CD) patients failing to attain adequate disease control with traditional 6-MP/AZA therapy., Methods: Ten CD patients with preferential 6-MMPR production upon 6-MP/AZA dose escalation were enrolled in an open-label pilot study. Seven of 10 patients had experienced dose-related 6-MP toxicities., Results: Seventy percent of the patients (7 of 10) responded or were in remission at week 16. Clinical response was evident by week 4 in most. 6-TGN levels were nine-fold higher with 6-TG treatment than with 6-MP, whereas 6-MMPR levels were undetectable. No patient developed a recurrence of hepatic or hematological toxicity., Conclusions: 6-TG was a safer and more efficacious thiopurine in this subgroup of IBD patients resistant to 6-MP therapy. Larger controlled trials are warranted to further evaluate both the short- and long-term safety and efficacy in this subgroup of patients as well as a broader spectrum of IBD patients.

We report the experience of 11 patients (of 60 planned patients) enrolled in a double-blind, placebo-controlled clinical trial of infliximab in patients with severe, active steroid-refractory ulcerative colitis. The study was terminated prematurely because of slow enrollment. Patients having active disease for at least 2 weeks and receiving at least 5 days of intravenous corticosteroids were eligible to receive a single intravenous infusion of infliximab at 5, 10, or 20 mg/kg body weight. The primary endpoint used in this study was treatment failure at 2 weeks after infusion. Treatment failure was defined as 1) unachieved clinical response as defined by a modified Truelove and Witts severity score, 2) increase in corticosteroid dosage, 3) addition of immunosuppressants, 4) colectomy, or 5) death. Safety evaluations included physical examination, clinical chemistry and hematology laboratory tests, and occurrence of adverse experiences. Four of 8 patients (50%) who received infliximab were considered treatment successes at 2 weeks, compared with none of 3 patients who received placebo. Improvement in erythrocyte sedimentation rates and serum concentrations of C-reactive protein and interleukin-6 correlated with the clinical response observed in patients receiving infliximab. Infusion with infliximab produced no significant adverse events. Infliximab was well tolerated and may provide clinical benefit for some patients with steroid-refractory ulcerative colitis.

Chemokines represent a large family of small cytokines, the main function of which is the attraction of leukocytes to different tissues. Several chemokines and their receptors have been shown to play a critical role in lymphoid development, mucosal immunity, and inflammation. In this article we review recent advances in chemokine physiology and their potential role in the pathogenesis of mucosal inflammation. We also discuss the potential for the use of chemokine or chemokine receptor antagonists as novel therapies for inflammatory bowel disease.

Mycophenolate mofetil (MMF) is a novel immunomodulator that may be effective in the treatment of chronic active and perianal Crohn's disease (CD). The aim of this study is to assess the efficacy of MMF in CD patients who failed or were intolerant of 6-mercaptopurine (6-MP) or azathioprine (AZA). Eleven CD patients were treated with MMF after a failed course of 6-MP/AZA, and their records reviewed retrospectively. Reasons for 6-MP/AZA intolerance or failure were recorded. Response to MMF was determined by calculation of the Harvey-Bradshaw index and ability to taper steroids. Adverse reactions to MMF were recorded. Eleven patients were identified who failed a previous trial of 6-MP/AZA and other immunomodulators and required immunomodulator therapy. Of 11 patients who started MMF, four had early adverse reactions within 8 weeks and stopped the medication. Of the remaining seven patients who took MMF for at least 8 weeks, one had a complete response, two had a partial response, and four had no response to the medication. In patients who failed 6-MP/AZA, MMF was of benefit in 3 of 11 patients with only one complete responder. This lower-than-expected response rate may indicate that patients who are resistant to 6-MP or AZA may also be resistant to MMF.

Chronic inflammatory bowel disease (IBD) presents as two major clinical forms, Crohn's disease (CD) and ulcerative colitis (UC). Genetic epidemiological studies and animal models suggest that inherited factors play significant roles in the susceptibility to both forms of IBD. From four genome-wide scans, putative susceptibility loci on chromosome 16 (IBD1 for CD), and on chromosomes 1, 3, 4, 6, 7, 10, and 12 for IBD, have been identified. Several other groups, including ours, have confirmed linkage to the loci on chromosomes 12 and 16. The aim of this study is to identify other potential susceptibility loci for CD with a genome-wide search approach. In our sample of 222 individuals from 46 families (20 Jewish and 26 non-Jewish), with a total of 65 sibpairs diagnosed with CD, we observed a novel locus with suggestive linkage [multipoint logarithm of the odds score (Mlod) > 2] at chromosome 14q11.2 (Mlod = 2.8, p = 0.0002). In addition, suggestive linkage was observed in our Jewish families at chromosome 17q21-q23 (Mlod = 2.1, p = 0.01) and chromosome 5q33-q35 (Mlod = 2.2, p = 0.0003). The syntenic regions of the latter locus are mapped within two putative loci on mouse chromosomes 11 and 18, which were identified in a mouse IBD model induced by dextran sulfate sodium (29). Our preliminary results provide potential evidence for several susceptibility loci contributing to the risk of CD. The observation of man-mouse synteny may accelerate the identification of CD susceptibility gene(s) on human chromosome 5.

A detailed investigation of the relationship between anti-neutrophil cytoplasmic antibodies (ANCA) status, HLA genotype, and clinical patterns of inflammatory bowel disease was carried out, involving 236 European patients resident in the United Kingdom [120 had ulcerative colitis (UC), 116 had Crohn's disease (CD)]. ANCA status was determined on coded plasma samples in Los Angeles using a two-stage assay [fixed neutrophil enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence], and HLA genotyping was carried out by polymerase chain reaction. The results provide evidence that ANCA reflect clinical and genetic heterogeneity within the inflammatory bowel diseases. In the UC patients, 78.3% were ANCA positive [64.2 perinuclear (pANCA)], but only 46.5% CD patients were ANCA positive (19.3% pANCA). Furthermore, mean ELISA binding was significantly lower in CD (14.5% +/- 18.8% versus 40.5% +/- 41.0% in UC, p = 2.31 x 10(-9)). Only 15 CD samples, all from patients with colonic disease, displayed ELISA > 20%; and the six CD patients with highest ELISA binding had clinical features very similar to ulcerative colitis. Moreover, in UC, significant relationships between ANCA status and genotype were noted. Thus, 92.7% of patients with the DR3 DQ2 TNF2 haplotype were ANCA positive [p = 0.03 versus DR3 DQ2 TNF2-negative patients (73.9%)]. ELISA binding was increased in DR3 DQ2 TNF2-positive patients (56.0 versus 35.7%, p = 0.02). In this population of UC, ANCA was not associated with DR2, DR4, or clinical pattern. These data emphasize the many factors that need to be considered in genetic marker studies in inflammatory bowel disease. Extensive disease heterogeneity, ethnicity, and methodological differences in ANCA detection are all pertinent.

T cell activation can lead to local tissue injury in organ culture studies of human fetal jejunum, either directly through cytotoxicity or indirectly by the release of cytotoxic cytokines. The goal of this study was to establish in vitro whether cytotoxic cytokines can be released by isolated colonic T cells and what cytokine interactions are required for killing of human colonic epithelial cells. Cytokine-containing supernatants were induced by incubating unseparated lamina propria lymphocytes (LPL) or mucosal T cell subpopulations (separated by indirect panning) with anti-CD3 and/or K562 target cells for 18 h at 37 degrees C. Cytokines were measured by cytotoxicity assays using L929 (murine fibroblast) and HT-29 (human colonic tumour) lines as target cells in combination with blocking anti-cytokine antibodies. Supernatants derived from unseparated, CD4+ (greater than 95% pure) and CD8+ (greater than 90% pure) LPL were cytotoxic to L929 targets (350 U/ml, 230 U/ml and 100 U/ml tumour necrosis factor-alpha, respectively). All or nearly all of the cytotoxicity was due to the presence of tumour necrosis factor-alpha (little or no tumour necrosis factor-beta was detected). These same supernatants were cytotoxic (up to 32% lysis at 1/4 dilution) to HT-29 targets in a 48-h 111In release assay. Recombinant tumour necrosis factor-alpha and interferon-gamma alone produced minimal killing of HT-29, but together killed the HT-29 target cells. Anti-tumour necrosis factor-alpha or anti-interferon-gamma alone blocked killing of HT-29 target cells by LPL-derived supernatants, although anti-tumour necrosis factor-beta had no effect upon killing of HT-29. These results demonstrate that human LPL T cells, triggered by addition of anti-CD3 and target cells, produce tumour necrosis factor-alpha and interferon-gamma, both of which are required for optimal killing of HT-29. Simultaneous release of these cytokines in the vicinity of epithelial cells during immune responses could play an important role in the mucosal damage in chronic inflammatory states such as inflammatory bowel disease.

An expanded T cell subpopulation (CD8+ Leu-7+) has previously been reported in the peripheral blood of patients with Crohn's disease. This subpopulation of T cells was associated with a 'covert suppressor' function, particularly in patients with mild/early Crohn's disease, suppressing immunoglobulin production in vitro when cultured in the presence of pokeweed mitogen. T cells with the same CD8+ Leu-7+ phenotype have also been shown to exhibit non-major histocompatability complex-restricted cytotoxicity when triggered by anti-CD3 antibodies, and this cytotoxic activity has also been shown to be elevated in patients with Crohn's disease. Because cytotoxic cells can have immunoregulatory properties, we investigated the possible relationship between the cytotoxic and 'covert suppressor' functions of the CD8+ Leu-7+ subset of T lymphocytes in patients with mildly active Crohn's disease. Although the correlation between T cell cytotoxic activity and the CD8+ Leu-7+ cells was confirmed, no evidence for covert suppressor activity was found; there were no significant differences between the amount of IgM secreted by B cells from normal subjects and patients with Crohn's disease when cultured with T cells at increasing T:B ratios. In addition, IgM production by peripheral blood B cells did not correlate with either the number of CD8+ Leu-7+ cells or with the level of cytotoxic T cell activity. Furthermore, when B cells and CD4+ T cells were co-cultured with increasing numbers of CD8+ T cells, there was no evidence for excessive suppressor T cell activity in Crohn's disease. Although some patients exhibited low levels of IgM production, this was due to diminished B cell function, rather than excessive T suppressor activity or defective T helper activity. We conclude that the CD8+ Leu-7+ T cell subset is associated with cytotoxic but not with enhanced or covert suppressor activity in Crohn's disease. The previously described covert suppressor function attributed to cells with this phenotype in Crohn's disease was not found to account for diminished B cell responsiveness in vitro and is unlikely to be of major pathophysiologic significance in the majority of patients.

Viable mononuclear and epithelial cells were dispersed from human colonic tissue by treatment with collagenase and ethylene diamino-tetra acetate (EDTA) and separated by centrifugal elutriation. Using a single cell cytotoxic assay, functional endogenous and interferon responsive mononuclear cytotoxic cells were detected. Compared to peripheral blood lymphocyte associated killer cells that had been exposed to similar treatment, these colonic killer cells demonstrated lower efficiency cytotoxicity of Molt-4 target cells. Furthermore, inefficient, but interferon responsive cytotoxic cells were present which bound and lysed freshly isolated autologous epithelial cells. The cytotoxicity of these colonic mononuclear natural killer (NK) like cells appeared specific in that cells bound but did not lyse NK resistant Raji cells, even after interferon activation.

In the present study we examined the mechanism of human natural killer cellular cytotoxicity (NKCC) augmentation by 5 min of moderate exercise and its interrelationship to in vitro interferon (IFN) activation. Cytotoxicity was measured by employing both a single-cell cytotoxic assay and a standard 3-hr chromium-51 (51Cr) release assay. The former was used to assess changes at the single NK cell--target cell level and the latter to assess changes in overall lytic capacity of a given population of NK cells. Several findings were obtained: (1) moderate exercise augmented NKCC in vivo by recruiting a 'new' population of active cytotoxic NK cells. (2) This 'new' population of active cells probably was derived from cells which can bind targets but are non-cytotoxic. (3) In a standard 51Cr-release assay, additional augmentation of these exercise-activated cells occurred in vitro following exposure to interferon. (4) This additional increase in cytotoxicity produced no alteration in the frequency of killer cells as viewed at the single cell level. (5) Thus interferon's capacity to increase further the overall lytic ability of exercise-activated NK cells was not due to its activation of an additional subset of pre-NK cells, but due to its increasing the capacity of effector--target lytic interactions (recycling) of the same set of NK and pre-NK cells.

In the present study we have investigated whether cell lines, which are resistant to spontaneous cytotoxicity, can be killed by lectin-dependent cellular cytotoxicity (LDCC), the expression of EAC (7S) receptors on LDCC effector cells, and the relationship between spontaneous cytotoxicity and LDCC when EAC (7S) receptor-positive or -negative subpopulations are tested against different target cell lines. We found that target cells which are resistant to spontaneous cytotoxicity can, indeed, be killed by LDCC, and that there is an inverse relationship between spontaneous cytotoxicity and LDCC, both when unfractionated lymphocytes were tested against different target cells and when fractionated cells were tested against cell lines highly susceptible to spontaneous cytotoxicity. The implications of these findings, in relation to the relative specificity of the spontaneous cytotoxicity system, are discussed.