Increased levels of lipoprotein (a) in Crohn's disease: a relation to thrombosis?

OBJECTIVE: Lipoprotein (a) is recognized as a risk factor for arterial and venous thrombosis, a property that might be related to its structural similarity to plasminogen. Since patients with inflammatory bowel disease frequently suffer from thromboembolic events, we studied the role of lipoprotein (a) in conjunction with lipids and apolipoproteins in Greek patients with ulcerative colitis and Crohn's disease. METHODS: Lipoprotein (a), total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, apolipoprotein A-1 and apolipoprotein B-100 were determined in sera from 129 consecutive fasting Greek patients with inflammatory bowel disease (66 with ulcerative colitis and 63 with Crohn's disease) and from 66 matched healthy controls. RESULTS: In Crohn's disease patients, the mean serum lipoprotein (a) level was significantly higher than in control patients (41.2 mg/dl vs 22.9 mg/dl; P = 0.005). Mean apolipoprotein A-1 and apolipoprotein B-100 levels were significantly lower in Crohn's disease patients than in the controls. In ulcerative colitis patients the mean levels of lipoprotein (a) and apolipoprotein A-1 were not significantly different to the controls, but the levels of apolipoprotein B-100 were significantly lower. Raised levels of lipoprotein (a) of > 30 mg/dl were found in 29 Crohn's disease patients (46%), 15 ulcerative colitis patients (23%) and 11 control patients (17%). Patients with active Crohn's disease had significantly higher mean lipoprotein (a) and lower apolipoprotein A-1 than patients with non-active disease. CONCLUSIONS: Our results suggest that Crohn's disease patients have different lipoprotein (a) and apolipoprotein patterns compared to ulcerative colitis patients and healthy controls. These changes in Crohn's disease patients may possibly expose them to a higher risk of thrombosis.     

Thrombotic vascular risk factors in inflammatory bowel disease.

BACKGROUND--Thrombosis may be an important effector mechanism in the pathogenesis of Crohn's disease. METHODS--This study therefore investigated the prevalence of independent thrombotic risk factors (factor VII coagulant activity, lipoprotein (a), fibrinogen, plasma triglycerides, and smoking) in patients with Crohn's disease, ulcerative colitis, and normal controls. RESULTS--In Crohn's disease (n = 75), the mean plasma VII:C, lipoprotein (a) and fibrinogen concentrations were significantly greater than in the normal population (n = 85). In ulcerative colitis (n = 35), only the mean factor VII:C concentration was significantly higher than normal. Ninety three per cent of patients with Crohn's disease and 86% of those with ulcerative colitis had at least one risk factor for thrombotic vascular disease, compared with 61% of the normal population (p < 0.001). CONCLUSIONS--In many young patients with inflammatory bowel disease, plasma concentrations of these prothrombotic factors were in excess of the limits that are regarded as posing an increased risk for the development of occlusive vascular disease.     

Risk of lymphoma in inflammatory bowel disease

OBJECTIVE: Inflammatory bowel disease with a subsequent diagnosis of non-Hodgkin's lymphoma has been reported. There is concern that the risk of developing lymphoma will rise with increasing use of immune modifier therapy. We determined the risk of non-Hodgkin's lymphoma in an U.S. population-based inception cohort, and evaluated the association between inflammatory bowel disease and lymphoma in our referral practice. METHODS: The records of all incidence cases of inflammatory bowel disease in Olmsted County, Minnesota, between 1950 and 1993 were reviewed for the diagnosis of lymphoma. Standardized incidence ratios (observed/expected) were used to estimate relative risk. In addition, the clinical features and outcomes of all patients with inflammatory bowel disease and lymphoma seen at Mayo Clinic between 1976 and 1997 were reviewed. RESULTS: Among 454 county residents diagnosed with inflammatory bowel disease, a single non-Hodgkin's lymphoma occurred in a patient with Crohn's disease. No cases were seen with ulcerative colitis. The estimated relative risk of lymphoma was 2.4 in Crohn's disease (95% confidence interval, 0.1-13), 0 in ulcerative colitis (0-6), and 1.0 in inflammatory bowel disease overall (0.03-6). Between 1976 and June 1997, 61 patients with inflammatory bowel disease and lymphoma (approximately 0.41%) were seen in the referral practice. In four patients with Crohn's disease (13%), potential neoplastic risk factors were identified-therapeutic radiation in 1, and use of purine analogs in 3 (median length of use, 11 months). CONCLUSIONS: Our population-based cohort study demonstrated that the absolute risk of non-Hodgkin's lymphoma remains quite small (0.01% per person-year). This risk may not exceed that in the general population. In our referral practice, immune modifier therapy could be potentially implicated in only 5% of cases of lymphoma occurring in the setting of inflammatory bowel disease.     

Bone mineral density is reduced in patients with Crohn''s disease but not in patients with ulcerative colitis: a population based study.

BACKGROUND: Patients with inflammatory bowel disease are at risk of developing metabolic bone disease. AIMS: To compare bone mineral density in patients with Crohn's disease with patients with ulcerative colitis and healthy subjects, and to evaluate possible risk factors for bone loss in inflammatory bowel disease. PATIENTS: 60 patients with Crohn's disease, 60 with ulcerative colitis, and 60 healthy subjects were investigated. Each group consisted of 24 men and 36 women. METHODS: Lumbar spine, femoral neck, and total body bone mineral density were measured by dual x ray absorptiometry (DXA), and Z scores were obtained by comparison with age and sex matched normal values. RESULTS: Mean Z scores were significantly lower in patients with Crohn's disease compared with patients with ulcerative colitis and healthy subjects. Patients with ulcerative colitis had bone mineral densities similar to healthy subjects. Use of corticosteroids, body mass index (BMI), and sex were significant predictor variables for bone mineral density in Crohn's disease. In ulcerative colitis only body mass index and sex were of significant importance. Disease localisation and small bowel resections had no influence on bone mineral density in patients with Crohn's disease. CONCLUSIONS: Patients with Crohn's disease have reduced bone mineral density. Several factors are probably involved, but the reduction is associated with corticosteroid therapy. When studying skeletal effects of inflammatory bowel disease, patients with Crohn's disease and those with ulcerative colitis should be evaluated separately.     

Inflammatory bowel disease is not associated with an increased risk of lymphoma.

BACKGROUND & AIMS: Previous studies of the risk of lymphoma in inflammatory bowel disease patients have provided conflicting results. This study examines the risk of Hodgkin's and non-Hodgkin's lymphoma among patients with inflammatory bowel disease. METHODS: The authors performed a retrospective cohort study using the General Practice Research Database. Inflammatory bowel disease patients were matched to randomly selected controls on age, sex, and primary care practice. Lymphoma rates were also compared with published age- and sex-specific rates. RESULTS: The study included 6605 patients with Crohn's disease, 10,391 with ulcerative colitis, and 60,506 controls followed for an average of 3.7, 3.9, and 4.4 years, respectively. The incidence of lymphoma was not increased in patients with inflammatory bowel disease (relative risk = 1.20; 95% CI, 0.67-2.06). In subgroup analyses, an increased risk was not observed among patients with Crohn's disease (relative risk = 1.39; 95% CI, 0.50-3.40) or ulcerative colitis (relative risk = 1.11; 95% CI, 0.51-2.19). Compared with inflammatory bowel disease patients not treated with azathioprine or 6-MP, the relative risk of lymphoma among the 1465 inflammatory bowel disease patients treated with these medications (average, 106 mg/day for 2.0 years) was 1.27 (95% CI 0.03-8.20). CONCLUSIONS: Patients with inflammatory bowel disease do not have an increased risk of lymphoma as compared with the general population. Although we cannot completely rule out a modest increased risk of lymphoma with azathioprine or 6-MP therapy, an increased risk was not observed in this cohort.     

Microsatellite Instability Is Uncommon in Intestinal Mucosa of Patients with Crohn's Disease

Patients with long-standing inflammatory bowel disease have an increased risk for colorectal carcinoma. Microsatellite instability occurs in colonic neoplasms and has been reported in colonic tissues from patients with ulcerative colitis. Patients with Crohn's disease also have an increased risk for colorectal cancer, although it is lower than that associated with ulcerative colitis. This study was designed to determine whether microsatellite instability occurs in Crohn's disease, and whether it occurs with similar frequency to that observed in ulcerative colitis. In all, 177 tissue samples from 33 patients with Crohn's disease were evaluated for microsatellite alterations. Microsatellite instability occurred in five different tissue samples from one of 33 Crohn's disease patients. Four of the five tissue samples showed microsatellite instability at more than one locus. We conclude that microsatellite instability is less common in Crohn's disease than ulcerative colitis and may reflect differences in cancer risk between these two forms of inflammatory bowel disease.     

Influence of environmental factors on the onset and course of inflammatory bowel disease

Numerous environmental factors have been linked with inflammatory bowel disease. These include smoking, diet, hygiene, drugs, geographical and psychosocial factors. These factors may either increase the risk of or protect against developing this condition and can also affect the course of illness in a positive or negative manner. A number of studies have examined the influence of environmental factors on inflammatory bowel diseases as a whole as well as on ulcerative colitis and Crohn's disease separately. As there are differences in the pathogenesis of ulcerative colitis and Crohn's disease, the effect of environmental factors on their onset and course is not always similar. Some factors have shown a consistent association, while reports on others have been conflicting. In this article we discuss the current evidence on the roles of these factors on inflammatory bowel disease, both as causative/protective agents and as modifiers of disease course.     

Inflammatory bowel disease and leukemia

In a review of a large number of patients with inflammatory bowel disease, leukemia was observed in five patients with chronic ulcerative colitis and in two patients with Crohn's disease. In ulcerative colitis patients, there were three cases of acute myelocytic leukemia and one case each of acute lymphoblastic leukemia and chronic granulocytic leukemia. In Crohn's disease patients, there was one case each of chronic granulocytic leukemia and chronic lymphocytic leukemia associated with thrombocythemia. Sixteen other cases of leukemia have been reported to date in inflammatory bowel disease. All types of leukemia, but particularly acute myelocytic leukemia, have been described. There has been no single common feature as to type (whether ulcerative colitis or Crohn's disease), extent and course, or medical and surgical treatment of the bowel disease. The relative risk of leukemia in patients with ulcerative colitis was 5.3 [95% confidence interval 1.7 to 12.3 (P<0.01)] and of acute myelocytic leukemia 11.4 [95% confidence interval 2.3 to 24.9 (P<0.01)]. Our data on patients with Crohn's disease were not sufficient to assess the statistical significance of leukemia in this disease. This study suggests that there may be an increased risk of leukemia, particularly acute myelocytic leukemia, in ulcerative colitis. The causal relationship, if any, remains undetermined.     

Familial empirical risks for inflammatory bowel disease: differences between Jews and non-Jews.

The Jewish population has an increased frequency of inflammatory bowel disease compared with their non-Jewish neighbours. Genetic factors have been implicated in the aetiology of this disorder and may contribute to ethnic differences. This study determined the familial empirical risks for inflammatory bowel disease in the first degree relatives of inflammatory bowel disease probands (for both Jews and non-Jews) for the purpose of accurate genetic counselling and genetic analysis. A total of 527 inflammatory bowel disease patients from Southern California (291 Jews and 236 non-Jews) were questioned about inflammatory bowel disease in their first degree relatives (a total of 2493 individuals). Since inflammatory bowel disease has a variable and late age of onset, age specific incidence data were used to estimate the life time risks and to make valid comparisons between the different groups. In the first degree relatives of non-Jewish probands, the life time risks for inflammatory bowel disease were 5.2% and 1.6% when probands had Crohn's disease and ulcerative colitis respectively. These values were consistently lower than the corresponding risks for relatives of Jewish patients -7.8% and 4.5% for Crohn's disease and ulcerative colitis probands respectively (p value for comparison between Jews and non-Jews: 0.028; between ulcerative colitis and Crohn's disease: 0.005). These data provide the requisite basis for genetic counselling for these disorders in the white American population. In addition, these different empirical risks for relatives of Jewish and non-Jewish probands allow rejection of single Mendelian gene models for inflammatory bowel disease, but are consistent with several alternative genetic models.     

Colorectal cancer risk in Crohn＇s disease

There is recognized increased risk for colorectal cancer in patients with inflammatory bowel disease, particularly in long-standing and extensive ulcerative colitis. There also appears to be an increased rate of intestinal cancer in Crohn＇s disease, including both colon and small bowel sites. In Crohn＇s disease, evidence suggests that detection of colorectal cancer may be delayed with a worse prognosis. Some risk factors for cancer in Crohn＇s disease include the extent of inflammatory change within the colon and the presence of bypassed or excluded segments, inclu- ding rectal ＂stump＂ cancer. In addition, the risk for other types of intestinal neoplasms may be increased in Crohn＇s disease, including lymphoma and carcinoid tumors. Earlier detection of colorectal cancer based on colonoscopy screening and surveillance may be achieved but, to date, this has not translated into a positive survival benefit. Moreover, newer staining methods and evolving micro-endoscopic techniques show promise, but have not significantly altered management. Future research should focus on development of molecular or other bio-markers that might predict future dysplasia or cancer development in Crohn＇s disease.     

Skeletal morbidity in inflammatory bowel disease

Patients with Crohn's disease are at increased risk of developing disturbances in bone and mineral metabolism because of several factors, including the cytokine-mediated nature of the inflammatory bowel disease, the intestinal malabsorption resulting from disease activity or from extensive intestinal resection and the use of glucucorticoids to control disease activity. Inability to achieve peak bone mass when the disease starts in childhood, malnutrition, immobilization, low BMI, smoking and hypogonadism may also play a contributing role in the pathogenesis of bone loss. The relationship between long-term use of glucocorticoids for any disease indication and increased risk for osteoporosis and fractures is well established. However, the relationship between Crohn's disease and ulcerative colitis and bone loss remains controversial. Depending on the population studied the prevalence of osteoporosis has thus been variably reported to range from 12 to 42% in patients with inflammatory bowel disease (IBD). In IBD most studies demonstrate a negative correlation between bone mineral density (BMD) and glucocorticoid use, but not all authors agree on the relationship between long-term glucocorticoid use and continuing bone loss. Whereas prospective studies do suggest sustained bone loss at both trabecular and cortical sites in long-term glucocorticoid users with inflammatory bowel disease, a decrease in bone mass is also observed in patients with active Crohn's disease not using glucocorticoids, and bone loss is not universally observed in patients with Crohn's disease using orally or rectally administered glucocorticoids. Data on vertebral fractures are scarce and there is no agreement about the risk of non-vertebral fractures in patients with Crohn's disease, although it has been suggested that non-vertebral fracture risk may be increased by up to 60% in patients with IBD. A recent publication reports an increased risk of hip fractures in Crohn's disease related to current and cumulative corticosteroid use and use of opiates, although these fractures could not be related to the severity of osteoporosis. The issue of the magnitude of the problem of osteoporosis has become particularly relevant in Crohn's disease, since the ability of therapeutic interventions to beneficially influence skeletal morbidity has been clearly established in patients with osteoporosis, whether post-menopausal women, men or glucocorticoid users. The main question that arises is whether all patients with Crohn's disease should be treated with bone protective agents on the assumption that they all have the potential to develop osteoporosis or whether the use of these agents should be restricted to patients clearly at risk of osteoporosis and fractures, providing these can be identified. We recommend, based on the available literature and our own experience, that all patients with Crohn's disease should be screened for osteoporosis by means of a bone mineral density measurement in addition to full correction of any potential calcium and vitamin D deficiency, to allow timely therapeutic intervention of the patient at risk while sparing the vast majority unnecessary medical treatment.     

Prevalence of hepatitis C in patients with chronic inflammatory bowel disease in the region of Nice and evaluation of risk factors

OBJECTIVES: To estimate the prevalence of viral hepatitis C markers and to determine independent risk factors in a population of patients with inflammatory bowel disease. METHODS: We studied 117 consecutive out-patients (male/female, 53/64; mean age 41 +/- 16 yrs) with ulcerative colitis (43 patients) or Crohn's disease (74 patients). Anti-hepatitis C virus antibodies were tested with a third generation Elisa test. The following risk factors were tested for each patient: duration of inflammatory bowel disease, number of colonoscopies, history of surgical procedures, blood transfusions, intravenous drug abuse and immunosuppressive treatments. RESULTS: The seroprevalence of hepatitis C virus was 5.98% (7/117). The only risk factor independently associated with serological markers for hepatitis C virus was blood transfusion (odds ratio: 7.77; confidence interval: 95% (1.63-49.09); P=0.012). CONCLUSIONS: The prevalence of hepatitis C virus infection was high in patients with inflammatory bowel disease, mainly due to blood transfusions. Colonoscopies and surgical procedures were not found to be additional risk factors for infection with hepatitis C virus.     

Cholelithiasis in inflammatory bowel disease

Cholelithiasis is considered an extraintestinal manifestation of Crohn's ileitis but has not been associated with ulcerative colitis. To evaluate if an increased risk of cholelithiasis exists in patients with ulcerative colitis, biliary ultrasonography was performed on 159 patients with inflammatory bowel disease, 114 patients with ulcerative colitis, and 45 patients with Crohn's disease. A control population of 2453 residents of the town near the authors' institute was also studied. An echographic survey of gallstones was performed on the control subjects, who participated in the Multicentrica Italiana Colelitiasi (MICOL). Seventeen patients with inflammatory bowel disease had gallstones (10.7 percent), 11 patients with ulcerative colitis had gallstones (9.6 percent), and 6 patients with Crohn's disease had gallstones (13.3 percent). In the control population, diagnosis of cholelithiasis was made in 239 subjects (9.7 percent). An estimate of the relative risk (odds ratio) of gallstones in ulcerative colitis and Crohn's disease and also in 4 subgroups formed on the basis of the extent of disease (total ulcerative colitis, partial ulcerative colitis, Crohn's disease with ileitis, Crohn's disease without ileitis) with respect to the general population was calculated using logistic regression with gallstones, sex, age, and body mass index as independent variables and inflammatory bowel disease as a dependent variable. The author's findings show an increased risk of gallstones in both patients with Crohn's disease (odds ratio = 3.6; 95 percent confidence limits = 1.2 - 10.4; P = 0.02) and patients with ulcerative colitis (odds ratio = 2.5; 95 percent confidence limits = 1.2 - 5.2; P = 0.01). The risk was highest in patients with Crohn's disease involving the distal ileum (odds ratio = 4.5; 95 percent confidence limits = 1.5 - 14.1; P = 0.009) and in patients with total ulcerative colitis extending to the cecum (odds ratio = 3.3; 95 percent confidence limits = 1.3 - 8.6; P = 0.01). These results confirm that there is an increased risk of gallstones in Crohn's ileitis but they show that there also exists an increased risk in patients with total ulcerative colitis.     

Increased serum levels of YKL-40 in patients with inflammatory bowel disease

BACKGROUND AND AIMS: Initiation of a fibrotic process has been suggested as part of the intestinal response to chronic inflammation in inflammatory bowel disease. YKL-40 has been proposed as a new serum marker of fibrosis. We studied compared the serum levels of YKL-40 in patients with ulcerative colitis or Crohn's disease with inflammatory and healthy controls. PATIENTS AND METHODS: YKL-40 serum levels were measured in 179 patients with inflammatory bowel disease (94 ulcerative colitis, 85 Crohn's disease), in 23 with intestinal inflammation of other causes, and 70 matched healthy controls using a commercially available enzyme-linked immunosorbent assay. YKL-40 levels were assessed in terms of disease activity, type and localization. RESULTS: Mean serum YKL-40 levels were 102.6+/-82.7 ng/ml in ulcerative colitis patients and 112.2+/-83.7 ng/ml in Crohn's disease patients, significantly higher than in healthy controls (64.1+/-21.4 ng/ml) but not significantly different from inflammatory controls (77.8+/-23.1 ng/ml). Disease activity and C-reactive protein levels were significantly correlated with YKL-40 levels in both ulcerative colitis and Crohn's disease. Crohn's disease patients with ileum localization had significantly higher YKL-40 levels than those with ileocolonic or colonic disease. Patients with stenotic disease had mean YKL-40 levels not significantly different than those with nonstenotic disease. CONCLUSION: Serum levels of YKL-40 are increased in patients with inflammatory bowel disease, and this is associated with the inflammatory process rather than with the degree of fibrosis.     

An increased risk of Crohn's disease in individuals who inherit the HLA class II DRB3*0301 allele.

The role of inflammatory T cells in Crohn's disease suggests that inherited variations in major histocompatibility complex (MHC) class II genes may be of pathogenetic importance in inflammatory bowel disease. The absence of consistent and strong associations with MHC class II genes in Caucasian patients with inflammatory bowel disease probably reflects the use of less precise typing approaches and the failure to type certain loci by any means. A PCR-sequence-specific oligonucleotide-based approach was used to type individual alleles of the HLA class II DRB1, DRB3, DRB4, and DRB5 loci in 40 patients with ulcerative colitis, 42 Crohn's disease patients, and 93 ethnically matched healthy controls. Detailed molecular typing of the above alleles has previously not been reported in patients with inflammatory bowel disease. A highly significant positive association with the HLA-DRB3*0301 allele was observed in patients with Crohn's disease (P = 0.0004) but not in patients with ulcerative colitis. The relative risk for this association was 7.04. Other less significant HLA class II associations were also noted in patients with Crohn's disease. One of these associations involved the HLA-DRB1*1302 allele, which is known to be in linkage disequilibrium with HLA-DRB3*0301. These data suggest that a single allele of an infrequently typed HLA class II locus is strongly associated with Crohn's disease and that MHC class II molecules may be important in its pathogenesis.     

Seasonal variations in onset of symptoms in Crohn''s disease

BACKGROUND: Seasonal variations in onset of symptoms have been reported in ulcerative colitis but not in Crohn's disease. AIM.: To investigate whether our inflammatory bowel diseases patients presented seasonal variations in onset of symptoms. PATIENTS AND METHODS: Patients with a diagnosis of inflammatory bowel diseases established between 1995 and May 2004, and consecutively observed from June 2003 to May 2004, were included in the study. Onset of symptoms (year, season and month) was recorded. Expected onsets with a uniform distribution during the year were calculated and compared to observed onsets. Statistical analysis: chi-square test, odds ratio (95% confidence interval). RESULTS: Overall 425 inflammatory bowel diseases patients were enrolled. Onset of symptoms (year and season) was established in 353/425 patients (83%; 150 Crohn's disease; 203 ulcerative colitis). Onset of symptoms in inflammatory bowel diseases patients as a whole occurred more frequently in spring-summer compared to autumn-winter (odds ratio 1.39; 95% confidence interval 1.03-1.87; p<0.03). This variation was observed in Crohn's disease (odds ratio 1.59; 95% confidence interval 1.00-2.51; p<0.05) and a similar trend, although not significant, was observed in ulcerative colitis (odds ratio 1.27; 95% confidence interval 0.86-1.88; p=0.27). CONCLUSIONS: These data indicate that onset of Crohn's disease symptoms occurred more frequently during spring-summer. A similar trend was observed in ulcerative colitis. Environmental factors, such as associated infections, smoking, use of drugs and seasonal changes in immune function may be responsible for triggering the clinical onset of inflammatory bowel diseases.     

Diagnosis of small bowel Crohn's disease: a prospective comparison of capsule endoscopy with magnetic resonance imaging and fluoroscopic enteroclysis

BACKGROUND AND AIMS: The diagnostic yield of capsule endoscopy (CE) compared with magnetic resonance imaging (MRI) in small bowel Crohn's disease is not well established. We prospectively investigated CE, MRI, and double contrast fluoroscopy in patients with suspected small bowel Crohn's disease. METHODS: Fifty two consecutive patients (39 females, 13 males) were investigated by MRI, fluoroscopy and--if bowel obstruction could be excluded--by CE. In 25, Crohn's disease was newly suspected while the diagnosis of Crohn's disease (non-small bowel) had been previously established in 27. RESULTS: Small bowel Crohn's disease was diagnosed in 41 of 52 patients (79%). CE was not accomplished in 14 patients due to bowel strictures. Of the remaining 27 patients, CE, MRI, and fluoroscopy detected small bowel Crohn's disease in 25 (93%), 21 (78%), and 7 (of 21; 33%) cases, respectively. CE was the only diagnostic tool in four patients. CE was slightly more sensitive than MRI (12 v 10 of 13 in suspected Crohn's disease and 13 v 11 of 14 in established Crohn's disease). MRI detected inflammatory conglomerates and enteric fistulae in three and two cases, respectively. CONCLUSION: CE and MRI are complementary methods for diagnosing small bowel Crohn's disease. CE is capable of detecting limited mucosal lesions that may be missed by MRI, but awareness of bowel obstruction is mandatory. In contrast, MRI is helpful in identifying transmural Crohn's disease and extraluminal lesions, and may exclude strictures.     

Serum and faecal lysozyme in inflammatory bowel disease.

Lysozyme (EC 3.2.1.17) concentrations were measured in the serum and stools of patients with inflammatory bowel disease and compared with the concentrations in similar material from normal controls, patints with non-inflammatory gastrointestinal disease, and patients without gastrointestinal disease. By the turbidometric method, values of lysozyme (microgram/ml +/- SD) are considerably greater in the serum of patients with active Crohn's disease (9.2 +/- 2.7) than in the serum of healthy controls (4.4 +/- 2.0). They do not, however, distinguish individual patients with Crohn's disease from those with ulcerative colitis nor from those with a variety of other gastrointestinal conditions. The lysoplate method gives much higher values for serum lysozyme than the turbidometric method but there is a considerable overlap between the results for patients with Crohn's disease (60.1 +/- 30.7) and normal controls (27.4 +/- 17.5). There is only a moderate correlation between the results given by the two methods (r = 0.56) and it is suggested that factors other than enzyme activity and methodological variation are responsible for the observed differences. This is supported by the finding that, with Crohn's disease in remission, serum lysozyme values (lysoplate) return to normal values but with the turbidometric method remain raised. Mean faecal lysozyme levels, expressed either as a concentration or as total daily excretion, in patients with inflammatory bowel disease are very significantly greater than values in healthy controls and in diseased subjects without diarrhoea but are not significantly different from those subjects with other causes of diarrhoea.     

Increased neutrophil receptors for and response to the proinflammatory bacterial peptide formyl-methionyl-leucyl-phenylalanine in Crohn's disease

Neutrophils have an important role in mediating tissue injury in inflammatory bowel disease. The proinflammatory peptide formyl-methionyl-leucyl-phenylalanine (FMLP), which is produced by intestinal bacteria, is a potent chemotactic factor for human neutrophils and has been used experimentally to induce acute colitis in animal models. Its action involves specific receptors on the surface of the neutrophil. Increased mucosal permeability, which has been described in Crohn's disease, might contribute to the pathogenesis of the intestinal lesions in this disease by means of increased absorption of FMLP and other gut-derived bacterial products. To evaluate the interaction between FMLP and neutrophils in patients with inflammatory bowel disease, we have studied the binding characteristics and responsiveness of circulating neutrophils to this peptide. Neutrophils from patients with Crohn's disease but not those with ulcerative colitis were found to have significantly increased numbers of receptors for FMLP with similar affinity constants. This was associated with a significantly increased functional response to FMLP in chemiluminescence assays. Differences in neutrophils between Crohn's disease and ulcerative colitis are probably not intrinsic to the neutrophil but reflect their conditioning by the different inflammatory milieu of these diseases.