Crohn disease lymph node homogenates produce murine lymphoma in athymic mice

A tale of two diseases: the history of inflammatory bowel disease

'Inflammatory bowel disease' (IBD) sounds like a straightforward term - a disease of inflammation in the bowel. However, the history of IBD reveals a story of a nefariously complex set of idiopathic conditions. IBD defies definition, in part because its pathophysiology is not completely understood. For the same reason and despite substantial advances in research, IBD also defies cure. At best, IBD can be defined as a disease of disruption - disrupted physiology, microbiology, immunology and genetics. The term 'IBD' is most often used to describe two separate conditions: ulcerative colitis (UC) and Crohn's disease (CD). This paper reviews the history of IBD, considering the ever-evolving understanding of both UC and CD. Beyond its intrinsic interest, the history of IBD exemplifies a pattern that is becoming increasingly familiar in the 21st century - the story of a chronic, incurable disease that defies the best efforts to treat it.

Primary intestinal lymphoma complicating Crohn's disease

A 32-year-old man with a 12-year history of Crohn's disease of the colon was found to have a 5-cm cecal mass on colonoscopy. Histology examination of the lesion revealed high-grade B-cell lymphoma of Burkitt's type. He was treated with chemotherapy and has done well in the past 12 months. Review of the literature reveals 30 cases of lymphoma in patients with a history of Crohn's disease.

Review article: the risk of lymphoma associated with inflammatory bowel disease and immunosuppressive treatment

Lymphoma complicating inflammatory bowel disease is well described. Whether the risk of lymphoma is increased by immunosuppressive treatment with azathioprine, 6-mercaptopurine or infliximab is a common concern among patients and physicians considering using these agents. This review aims to quantify the lymphoma risk in inflammatory bowel disease and the added risk attributable to these treatments. The evidence from published cases is that lymphomas occur at sites of active inflammatory bowel disease more often than expected for this to be a chance association. Studies on inflammatory bowel disease populations are conflicting, with some follow-up studies from large inflammatory bowel disease clinics showing an increase in lymphoma incidence, while other population-based studies show little or no increase in risk of lymphoma. A small increase in lymphoma risk in inflammatory bowel disease, perhaps 2-3-fold, may be compatible with both sets of data. Studies of the risks associated with immuno- suppression are less satisfactory, with smaller numbers of patients and relatively short follow-up. The available evidence would support a further increase in lymphoma risk associated with immunosuppressive treatment in inflammatory bowel disease of around fivefold compared to no immunosuppressive use, and tenfold compared to the general population. The risks appear to be less than that associated with renal and hepatic transplant-related immunosuppression. Infliximab treatment is still too new to make a full assessment of its long-term safety, but post-marketing surveillance currently suggests that lymphoma risk may not be any greater than that associated with azathioprine and 6-mercaptopurine. Population-wide surveillance for lymphoma in inflammatory bowel disease would be required to narrow the confidence intervals on these estimates of lymphoma risk in inflammatory bowel disease and immunosuppressive treatment.

Rectal lymphoma in ulcerative colitis treated with azathioprine

Primary malignant lymphoma of the bowel is a rare complication of inflammatory bowel disease. The association of gastrointestinal lymphoma, inflammatory bowel disease and prior immunosuppression remains unclear. We report the first case of azathioprine-treated ulcerative colitis developing rectal lymphoma.

Ulcerative Colitis and Colonic Lymphoma: A Theoretical Link

Ulcerative colitis (UC) is an inflammatory disease of the colon and rectum. Although colonic adenocarcinoma is a recognized complication of UC there have been few reported cases of gastrointestinal lymphoma arising in this setting. We describe our experience with such a case and review the literature that attempts to explain possible genetic etiologies for the malignant transformation of gastrointestinal lymphoid tissue to lymphoma as well as a link between UC and lymphoma.

Increased incidence of non-Hodgkin's lymphoma in inflammatory bowel disease patients on immunosuppressive therapy but overall risk is low

BACKGROUND

There is concern that the incidence of non-Hodgkin's lymphoma (NHL) will rise with increasing use of immunosuppressive therapy.

AIMS

Our aim was to determine the risk of NHL in a large cohort of patients with inflammatory bowel disease (IBD), and to study the association between IBD, NHL, and immunosuppressive therapy.

METHODS

We studied 782 IBD patients (238 of whom received immunosuppressive therapy) who attended our medical centre between 1990 and 1999 (median follow up 8.0 years). Standardised incidence ratios (SIRs) and 95% confidence intervals (CI) were calculated. Expected cases were derived from 1995 age and sex specific incidence rates recorded by the National Cancer Registry of Ireland.

RESULTS

There were four cases of NHL in our IBD cohort (SIR 31.2; 95% CI 2.0-85; p=0.0001), all of whom had received immunosuppressive therapy: azathioprine (n=2), methotrexate (n=1), and methotrexate and cyclosporin (n=1). Our immunosuppressive group had a significantly (59 times) higher risk of NHL compared with that expected in the general population (p=0.0001). Three cases were intestinal NHL and one was mesenteric. Mean age at NHL diagnosis was 49 years, mean duration of IBD at the time of NHL diagnosis was 3.1 years, and mean duration between initiation of immunosuppressive therapy and diagnosis of NHL was 20 months.

CONCLUSIONS

Although underlying IBD may be a causal factor in the development of intestinal NHL, our experience suggests that immunosuppressive drugs can significantly increase the risk of NHL in IBD. This must be weighed against the improved quality of life and clinical benefit immunosuppressive therapy provides for IBD patients.

Extraintestinal non-Hodgkin's lymphoma presenting as obstructive jaundice in a patient with Crohn's disease

We report the case of a 58-yr-old woman, previously diagnosed with Crohn's disease of the duodenum, who presented with jaundice and an epigastric mass. Diagnostic studies revealed an extraintestinal non-Hodgkin's lymphoma located near the head of the pancreas and causing obstructive jaundice. A review of the literature indicates the rarity of this association. We discuss the etiology, pathogenesis, and management of extraintestinal lymphomas in patients with Crohn's disease.

Colitis ulcerosa complicated by malignant lymphoma: case report and analysis of published works

A 51 year old woman with a two year history of ulcerative colitis developed a wide spread gastrointestinal non-Hodgkin's lymphoma of low grade malignancy (MALT-lymphoma) involving upper and lower gastrointestinal tract, spleen, and bone marrow. After chemotherapy, clinical symptoms improved and lymphocytic infiltrates disappeared. Thirty nine cases of ulcerative colitis and 22 cases of Crohn's disease complicated by gastrointestinal lymphomas reported in published works are reviewed. In inflammatory bowel diseases any dense lymphocytic infiltrates seen in biopsy specimens obtained from ulcerative colitis or Crohn's disease should be assessed to exclude gastrointestinal lymphoma.

Mycobacterium paratuberculosis monoassociated nude mice as a paratuberculosis model

In this study, a paratuberculosis (Johne's disease) model was developed by intragastrically dosing gnotobiotic athymic nude mice with Mycobacterium paratuberculosis. The mice infrequently shed bacilli from their intestinal tracts during the first 4 months after inoculation. Following this time, increasing numbers of M. paratuberculosis (greater than 4.0 log10 bacilli per fecal pellet by 40 weeks) were recovered from the feces of the 12 mice that remained in the isolator. A similar pattern of recovery of M. paratuberculosis was obtained from the ileum, cecum, colon, and liver. Histopathologic lesions and acid-fast bacilli were rare during the first 4 months of infection and then, with time, increased in prevalence and severity. Mice maintained for 7 months or longer exhibited severe granulomatous inflammation and large numbers of acid-fast bacilli in the gastrointestinal tract and liver (up to 10(8) log10 colony forming units per gram wet weight). Five mice maintained for 7 months or more developed clinical signs consistent with those seen in paratuberculosis (weight loss, chronic diarrhea); three of these mice eventually died or became moribund and were euthanatized. M. paratuberculosis monoassociated mice released increased levels of tumor necrosis factor activity into their sera, as compared to uninfected control mice, when they were injected with bacterial lipopolysaccharide. The clinical signs, fecal shedding of M. paratuberculosis, granuloma formation, and progressive bacillary multiplication observed with these mice are consistent with naturally occurring M. paratuberculosis infection of ruminants (Johne's disease). This model will be useful for future studies of immunoregulation and antimicrobial therapy of paratuberculosis.

Hybridomas using athymic nude mouse injected with Crohn's disease (CD) tissue filtrate. Immunoreactivity of the hybridomas with CD sera

Injections of Crohn's disease (CD) tissue filtrates produce lymphoma and hyperplastic lymph nodes from plasma cell hyperplasia (PCH) in athymic nude (nu/nu) mice; these lymphoid tissue contain an antigen(s) recognized by CD serum/gamma G immunoglobulin (IgG). To immortalize the "CD-reactive antigen(s)," the authors fused the lymphoid cells from a CD tissue filtrate primed nu/nu mouse with nonsecretory mouse myeloma cells. Hybrids were screened and selected based on their reactivity with CD serum IgG, but not with control serum IgG in an indirect immunofluorescence assay (IF). Two CD-positive hybridomas were examined by IF with sera from 47 CD, 38 ulcerative colitis (UC), 13 controls with other gastrointestinal diseases, 19 with autoimmune diseases, and 21 normal subjects. Sera from 16 CD patients (34%) reacted with the two hybridomas, but only one of 38 UC sera and none of the 53 other disease or normal control sera reacted. The immunoreactivity of CD sera was significantly higher than UC sera (P less than 0.01) and each of the other groups (P less than 0.007). Using immunoperoxidase techniques at light and electron microscopic levels, the authors localized CD-associated antigen(s) in the plasma membrane of the two hybridomas. Further characterization of these hybridomas and the immunoreactive protein(s) may provide an important probe(s) for the diagnosis and the understanding of the pathogenesis of CD.

Primary malignant lymphoma of the large intestine complicating chronic inflammatory bowel disease

Ten cases of malignant lymphoma of the colon and rectum complicating chronic inflammatory bowel disease are presented. Seven patients had chronic ulcerative colitis with a history varying from 6 to 20 years. There was extensive colitis in six of these patients and left-sided colitis in one. All seven lymphomas showed the pathological and immunohistological features of primary B-cell tumours of the gastrointestinal tract with a predominance of high-grade tumours. Three patients had Crohn's disease of the large intestine complicated by malignant lymphoma of the sigmoid colon or rectum. The history of Crohn's disease varied from 30 months to 20 years and in each case there was fissuring and fistulae. There was extensive anal involvement in two cases. Histologically the three lymphomas were heterogeneous: one was of 'granulomatous' T-cell type and the other two were markedly polymorphic and of equivocal phenotype. They were also characterized by numerous multinucleate tumour giant cells. Primary colorectal malignant lymphoma should be regarded as a rare, but significant, complication of ulcerative colitis. Immunosuppression may be an additional factor in the genesis of intestinal lymphoma in Crohn's disease. The prognosis appears to be dependent on factors already known to be of prognostic significance in primary gut lymphomas: a predominance of high-grade tumours suggests that the outlook is generally worse than that for idiopathic primary large intestinal lymphoma.

Intestinal multiplication of Mycobacterium paratuberculosis in athymic nude gnotobiotic mice

In this study gnotobiotic mice were inoculated with a human isolate of Mycobacterium paratuberculosis (strain Linda; ATCC 43015) in an attempt to investigate the pathogenesis of intestinal paratuberculosis. Mycobacterium paratuberculosis-monoassociated nu/+ mice developed a persistent low-level intestinal infection but did not support progressive bacillary multiplication. In contrast, monoassociated nu/nu mice eventually harbored approximately 10(7) M. paratuberculosis per g of intestinal tissue. Acid-fast bacilli and granulomas were observed in the intestinal mucosa and livers of nu/nu but not nu/+ mice. Similar results were obtained after intragastric inoculation of M. paratuberculosis into nu/+ and nu/nu flora-defined mice. These observations suggest that the presence of an intact cellular immune system is important for limiting intestinal multiplication of M. paratuberculosis. The results of this study may be relevant to our understanding of the pathogenesis of Johne's disease in ruminants and of human inflammatory bowel diseases that have a mycobacterial etiology (e.g., some cases of Crohn's disease and Mycobacterium avium-Mycobacterium intracellulare enteritis in patients with acquired immunodeficiency syndrome).

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

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

Application of an immunofluorescence assay for Crohn's disease using primed nude mouse lymph nodes to a United States/Mexican border population

Previous studies using an indirect immunofluorescence (IF) technique found that sera from patients with Crohn's disease (CD) frequently contained antibody that recognized an antigen(s) in CD tissue filtrate-primed lymphoid tissue from athymic nude (nu/nu) mice. The present study examined the reproducibility of this IF assay in a different laboratory setting and used patients with infectious diarrhea. We examined the immunoreactivity of 113 sera from eight patients with Crohn's disease, 11 with ulcerative colitis, 62 patients with infectious diarrhea, 22 nondiarrheal disease controls, and ten normal adults. Sera were absorbed with nu/+BALB/c mouse serum proteins coupled to Sepharose 4B to remove nonspecific binding. All sera were coded and tested against at least 2 of 4 lymph nodes from nu/nu mice that were previously inoculated with either CD tissue filtrate or with a passaged CD-induced nu/nu lymphoma. Reference positive CD sera and negative control sera were run in parallel during each assay. Sera from three CD patients consistently showed positive IF. None of the sera from patients with infectious diarrhea, other disease controls, or normals were positive. These results demonstrate the reproducibility of the IF assay using CD tissue-primed nude mouse lymph nodes and the preferential immunoreactivity of CD sera.

Histological response and antigen transmission in the lymph nodes of athymic nu/nu mice inoculated with Crohn's disease tissue filtrates

Lymph node histology and antigen transmission in the nu/nu mouse in response to animal inoculation with Crohn's disease tissue filtrates were re-evaluated. We found that a hyperplastic lymph node response in nu/nu mice occurred with Crohn's disease (CD), ulcerative colitis (UC), or other intestinal disease (OID) tissue inoculations. In addition, antigen transmission to lymph nodes as detected by indirect immunofluorescence using CD sera was observed in all inoculation groups. The immunofluorescent reaction also occurred independently of lymph node histology. Thus, we confirm that CD sera recognize an antigen(s) expressed in lymph nodes of athymic mice inoculated with CD tissue filtrates. The antibody (or antibodies) in CD sera was not specific for this 'CD antigen or antigens', however, as tested in the nu/nu mouse system, because the CD sera antibodies also recognised antigens in UC inoculated and OID inoculated animals.

Demonstration of Crohn's disease tissue-specific proteins by enzyme-linked immunosorbent assay (ELISA)

Theories on the etiology of Crohn's disease have included extrinsic agents and intrinsic bowel wall defects. We sought to determine the presence of immunoreactive antigens specific to Crohn's disease tissue by modifying the enzyme-linked immunosorbent assay. Tissue proteins were extracted from four patients with Crohn's disease and from four normal segments of colon from patients with colonic cancer. These tissue extracts were further purified on Con A Sepharose 4B affinity column. The glycoproteins eluted from this column were adsorbed by polystyrene plates as antigen and tested against 85 sera from patients with Crohn's disease, ulcerative colitis, other diarrheal diseases, and normal subjects. Sera from 48 patients with Crohn's disease showed significantly greater recognition of Crohn's disease tissue glycoproteins than sera from 27 disease controls (P less than 0.0125) and 10 normal subjects. These Crohn's disease sera also showed preferential recognition of glycoproteins extracted from Crohn's disease tissue compared to glycoproteins from normal colonic tissue (P less than 0.0005). The nature of these immunoreactive proteins, whether extrinsic or intrinsic, is not yet known. The ELISA may help in further characterization of Crohn's disease tissue-specific glycoprotein(s) and to develop a clinically useful serological test.

Seropositivity in Dutch Crohn's disease patients against primed nude mouse lymph nodes, and the difference with lymphocytotoxic antibodies

Sera from patients with Crohn's disease have been reported to show positive immunofluorescence with lymph nodes of nude mice primed with a filtrate of intestinal tissue affected with Crohn's disease. An indirect immunofluorescence assay was used to test sera of 63 unrelated patients with Crohn's disease, 21 with ulcerative colitis and 36 control subjects against lymph nodes of athymic nude (nu/nu) mice which had been injected with Crohn's disease and ulcerative colitis intestinal tissue filtrates. Forty nine per cent of Crohn's disease patients, 10% of ulcerative colitis patients and 3% of control sera reacted against lymph nodes of mice injected injected with ulcerative colitis intestinal tissue filtrates, 18% of Crohn's disease sera were with intestinal tissue homogenate from Dutch Crohn's patients. With the lymph nodes of mice injected with ulcerative colitis intestinal tissue filtrates, 18% of Crohn's disease sera were positive, whereas all ulcerative colitis and control sera were negative. Lymph nodes from 18 of the 19 mice injected with Crohn's disease tissue filtrates reacted with Crohn's disease sera, whereas only three of these 19 mice reacted with ulcerative colitis sera. A comparative study, carried out in parallel with Crohn's disease filtrate induced hyperplastic lymph nodes from the Bilthoven colony (W2) and from the New York colony (E671) using sera from 54 Crohn's disease patients from Leiden, showed immunoreactivity with 44 and 57% of the Crohn's disease sera against the two hyperplastic lymph nodes. Thirty six of the 54 Crohn's disease sera (67%) reacted with either or both lymph nodes. Only 11% of the Crohn's disease sera which were examined for immunofluorescence and lymphocytotoxic antibodies had lymphocytotoxic antibodies, whereas 40% and 46% of the same sera showed positive immunofluorescence against E671 and W2, respectively. Absorption studies indicated that lymphocytotoxic antibodies activity and the immunofluorescence against the primed nude mouse lymph node are mediated by different serum antibodies in Crohn's disease. The reproducibility of the nude mouse immunofluorescence test system for a preferential immunoreactivity of Crohn's disease sera against Crohn's disease tissue primed murine lymph nodes has been confirmed by the present study. Further studies are necessary to find out whether crossreactive antigen(s) as recognised by some of the Crohn's disease sera in mice injected with ulcerative colitis tissue filtrate is similar to the antigen(s) detected by Crohn's disease sera in mice injected with Crohn's disease tissue filtrates.

Experimental disease in infant goats induced by a Mycobacterium isolated from a patient with Crohn's disease. A preliminary report

Pilot studies were done to assess the pathogenicity of a Mycobacterium which had been recovered from the diseased ileum of a patient with Crohn's disease. In four separate studies, pairs of infant goats served as subjects. One of each pair received an oral inoculum of freshly harvested Mycobacterium species strain Linda suspended in cream. A littermate or stablemate which received only cream served as control. Necropsies were done at three, five, six, and 10 months postinoculation. Each of the four inoculated animals developed segmental granulomatous disease of the ileum or ileum and more proximal segments of small intestine, and regional lymph nodes. The earliest lesion occurred in Peyer's patches of the ileum and consisted of granulomatous clusters of epithelioid cells and giant cells, without caseation, which often occurred in a mantle of lymphocytes between the germinal centers and the muscularis mucosae. Nine of 10 such granulomas were free of acid-fast bacilli. In more advanced lesions, there was confluence of granulomas and ulceration of the mucosal surface. Two of the four inoculated animals also had lymphocytic lymphangitis in affected segments. Although the Mycobacterium Linda was recovered from intestinal segments of all four animals, acid-fast bacteria were not demonstrable in the intestines in two of them. Control animals remained free of lesions and acid-fast bacilli and were negative by bacteriologic culture. The Mycobacterium species strain Linda represents an enteric pathogen capable of inducing granulomas of the distal small intestine of susceptible species. The lesions produced have distinct similarities to those occurring in Crohn's disease.

Animal models of inflammatory bowel disease--an overview

It is obvious from the above discussion that, whereas no really clear-cut animal model of IBD has been established, a number of specific insights into the nature of the human illness can be derived from the study of naturally occurring and induced gastrointestinal inflammations occurring in animals. One of the most important emerges from the finding that both immune complex deposition in the gastrointestinal tract as well as stimulation of the mucosal T-cell system results in an ulcerative colitis-like gastrointestinal inflammation. The simplest explanation of the fact that vastly different methods of inducing immune-mediated injury in the gastrointestinal tract can lead to a similar kind of gastrointestinal inflammation is that the inflammatory response in the gastrointestinal tract is rather restricted in its overall pathologic appearance and that the histologic lesions characteristic of ulcerative colitis and Crohn's disease can arise from primary disturbance of the B-cell system, the T-cell system, or both. Another explanation of this fact, however, is that no matter what the initial immunological disorder may be, the mechanism underlying the gastrointestinal inflammation ultimately comes to involve a response to materials in the mucosal environment so that pathologic events are inevitably channeled into an inflammatory pathway that is either ulcerative colitis-like or Crohn's disease-like in its final configuration. This second explanation is buttressed by other findings derived from the study of animal models which, in general, suggest that no matter what the initial result, an immunologic interaction against a constituent of the bowel flora determines the ultimate course of the gastrointestinal inflammation.(ABSTRACT TRUNCATED AT 250 WORDS)

Survival and tissue localization of xenogeneic human lymphocytes in hypothymic nude mice: observations in normal subjects and multiple sclerosis

The feasibility of using the hypothymic nude mouse as a transfer system for the study of cellular autoimmunity, by injection and tracing of 51chromium (Cr) or fluorescein labelled lymphocytes from humans, allogeneic or syngeneic mice was investigated. The localization of the injected cells was studied by radioisotopic counting or microscopy. For mouse cells there was better survival of syngeneic than allogeneic cells, and the pattern of distribution of injected mouse lymphocytes differed markedly from that of xenogeneic human lymphocytes. Thus, the lymph nodes and spleen were the predominant sites of localization of transferred syngeneic (BALB/c) lymphocytes, indicative of long recirculation of these cells, whereas the liver was the predominant site of localization of transferred human lymphocytes, and there was no evidence for recirculation of these cells. In studies on patients with multiple sclerosis, lymphocytes did not localize in neural tissue. The data indicate that the nude mouse is unlikely to be useful for the study of the tissue distribution of dispersed xenogeneic (human) lymphocytes.

Detection and partial characterization of Crohn's disease tissue specific proteins recognized by Crohn's disease sera

To identify immunoreactive proteins in Crohn's disease (CD) tissue, we examined intestinal tissues from eight patients with CD, seven patients with ulcerative colitis (UC) and four normal colon specimens from patients with colon carcinoma. Tissues were homogenized in 0.05 M Tris-buffered saline containing 2 mM phenyl-methyl-sulphonyl fluoride, and the cell free supernatants were incubated with sera from eight patients with CD, five with UC and five normal volunteers. Immune complexes formed in vitro were precipitated with pansorbin, washed with several detergents and analysed by SDS-polyacrylamide gel electrophoresis. When CD tissue was immunoprecipitated with CD sera, three major proteins of 160,000, 120,000 and 110,000 daltons were detected. Partial enrichment of these proteins were achieved when immune complexes formed in vitro were precipitated with polyethylene glycol followed by protein A-Sepharose 4B chromatography. Affinity gel chromatography and autoradiographic studies with purified serum IgG from CD patients further confirmed the presence of these immunoreactive proteins in CD tissue extracts. When similarly examined, these proteins were absent from UC and control tissue extracts after incubation with CD, UC or control sera. These studies suggest that CD tissue contains several proteins which are specifically recognized by CD patients' sera. Characterization of these immunoreactive proteins may provide an important lead in understanding the pathogenesis of CD.

Antiviral activity in sera of patients with Crohn's disease

Sera from patients with Crohn's disease were tested for antiviral activity using a microtiter assay with end points showing 50% reduction of cytopathic effects. Patients were significantly more likely to have serum antiviral activity equivalent to interferon levels of 20 or more units/ml than were control subjects. The mean antiviral activity in the patients' sera (34 +/- 20 (s.d.) units/ml) was significantly greater than that in the control subjects' sera (0.6 +/- 1.7 (s.d.) units/ml). Following acidification the mean antiviral activity of the patients' sera (28 +/- 17 (s.d.) units/ml) had not changed significantly while heat inactivation resulted in significant loss of activity (7.5 +/- 2.7 (s.d.) units/ml). These findings are suggestive of the presence of circulating leucocyte interferon in the sera of patients with Crohn's disease.

Cytopathic effects in cultures inoculated with material from Crohn's disease

Rectal biopsy homogenates, faecal samples, and leucocyte rich plasma obtained from 39 patients were inoculated into tissue cultures. A non-transmissible cytopathic effect was observed in cultures inoculated with material from patients with Crohn's disease. In a blind study this cytopathic effect was observed in three specimens from three patients with Crohn's disease, in six specimens from four patients with ulcerative colitis, and six specimens from five patients with upper gastrointestinal disease. The cytopathic effect is unlikely to be associated with the bowel diseases tested. These results are also consistent with the failure of others to isolate a virus by the techniques used. With the limited range of techniques used no evidence was obtained to implicate conventional viruses in the pathogenesis of Crohn's disease.

Induction of lymphoma in athymic mice: a model for study of the human disease

A murine lymphoma, designated L1, was produced in immunologically deficient nude mice after chronic antigenic stimulation by infection with the pinworms Aspiculuris tetraptera and Syphacia obvelata. In vivo, L1 involves primarily the spleen and lymph nodes, with infiltration of liver, kidney, and bone marrow also observed. It is characterized by large clusters of B cells and null cells, and by rare T cells. The lymphoma cells express murine leukemia virus antigens (gp70 and p30) on the surface. L1 can be passaged successfully both in vivo and in vitro. The lymphoblasts that proliferate in vitro are null, but injecton back into the mouse produces a similar pattern of B cells, null cells, and occasional T cells as seen in the mouse-to-mouse transfers. Infectious viruses have been isolated from L1 cells and from tissue culture supernates and have been identified as a B-tropic murine leukemia virus and a xenotropic virus. The possibilities of this model for studying the etiology of human lymphoma are discussed.