Reactive arthritis following an outbreak of Salmonella typhimurium phage type 193 infection

OBJECTIVES: To determine the occurrence and the clinical picture of reactive arthritis (ReA) following an outbreak of Salmonella typhimurium. METHODS: An outbreak of S typhimurium phage type DT 193 occurred in several municipalities in Finland in 1999. A questionnaire which had a specific emphasis on musculoskeletal symptoms was mailed to all 78 subjects with a positive stool culture. Based on the answers, all subjects with recent joint complaints were clinically examined or interviewed by telephone. RESULTS: Sixty three of 78 subjects (81%) returned the questionnaire. Of these 63 subjects, five (8%) fulfilled the criteria for ReA. All the five subjects with ReA were adults with oligo- or polyarthritis. The antigen HLA-B27 was positive in two of the four subjects tested. In two of five subjects with ReA, the duration of acute arthritis was over six months. Subjects who had received antimicrobial drugs developed acute musculoskeletal symptoms significantly (p=0.013) less often than those without such treatment. None of the subjects with ReA had received antimicrobial drugs before the onset of joint symptoms. CONCLUSIONS: The occurrence of ReA following an outbreak of S typhimurium was at the same level as in outbreaks due to other salmonella serotypes reported previously by us, indicating that the frequency of ReA after various outbreaks is approximately 10%. Early use of antimicrobial drugs may prevent the development of musculoskeletal symptoms.     

Modification of disease outcome in Salmonella-infected patients by HLA-B27

OBJECTIVE: To study whether HLA-B27 modifies the outcome of Salmonella infection in vivo. METHODS: The frequency of HLA-B27 was determined in 198 Salmonella-infected patients and 100 healthy controls by immunofluorescence and polymerase chain reaction. The excretion of Salmonella was monitored at monthly intervals. The symptoms of acute infection and possible joint involvement were evaluated using questionnaires. RESULTS: Thirty-eight of 198 Salmonella-infected patients (19.2%) and 13 of 100 healthy controls (13.0%) were HLA-B27 positive. The excretion of Salmonella did not differ significantly between HLA-B27-positive and -negative patients, or for patients with versus those without joint symptoms. As many as 35 patients (17.7%) reported Salmonella-triggered joint symptoms. Three of 14 patients (21.4%) with arthralgia, 5 of 13 patients (38.5%) with probable reactive arthritis (ReA), and 6 of 8 patients (75%) with confirmed ReA were HLA-B27 positive. The duration and severity of joint symptoms directly correlated with HLA-B27 positivity. Women reported Salmonella-induced pain and swelling of joints more frequently than men (P = 0.07 and P = 0.03, respectively). Patients with Salmonella-triggered joint symptoms reported abdominal pain and headache more frequently than patients without joint symptoms (P = 0.05 and P = 0.004, respectively). CONCLUSION: HLA-B27 did not (at least, not strongly) confer susceptibility to Salmonella infection. Salmonella excretion correlated neither with HLA-B27 positivity nor with the occurrence of joint symptoms. Joint symptoms were surprisingly common during or after Salmonella infection. HLA-B27-positive patients had a significantly increased risk of developing joint and tendon symptoms. Moreover, HLA-B27 positivity correlated with the development of more severe and prolonged joint symptoms.     

Low incidence of reactive arthritis in children following a salmonella outbreak

OBJECTIVES: To assess the incidence of reactive arthritis (ReA) in an outbreak of salmonella infection in a large cohort of children in Germany. METHODS: A few days after the salmonella outbreak all parents of affected children and all paediatricians and general practitioners in the region were provided with detailed information about the possibility of ReA. Six weeks after the outbreak a telephone call was made to all general practitioners and paediatricians to identify patients with ReA. Ten weeks after the outbreak a questionnaire assessing symptoms of ReA was mailed to all parents, and after a period of 4 months paediatricians and general practitioners were contacted again to search for additional unreported cases of ReA. RESULTS: Of the 286 children (age range 11 months to 9 years) with diarrhoea and stool cultures positive for Salmonella enteritidis lysotype 8/7, not a single case of arthritis was reported over the 4 month period. However, six children (2%) had arthralgia of various duration (1 day to 6 weeks) with a single recurrence in one child. The joint pattern was oligoarticular and lower limb joints (knee/ankle) were affected exclusively. CONCLUSION: The incidence of ReA after salmonella infection in children appears to be very low which may be related to differences in the immune response between children and adults.     

Reactive arthritis and other sequelae following sporadic Salmonella typhimurium infection in British Columbia,Canada: a case control study

OBJECTIVE: To describe sequelae occurring in the 3 months after sporadic Salmonella typhimurium (ST) infection in British Columbia (BC), Canada. METHODS: We compared the incidence of sequelae to similar symptoms in controls; identified risk factors for developing sequelae; identified the incidence of reactive arthritis (ReA) as diagnosed by a rheumatologist, and assessed primary care physician diagnosis of ReA. A questionnaire was administered by telephone to cases of ST occurring in BC between December 1, 1999, and November 30, 2000; and to controls obtained from the BC provincial client registry. Cases reporting symptoms were followed up by a rheumatologist. RESULTS: Thirty-five of 66 (53%) cases reported any symptom, 17 (26%) reported joint symptoms. The Mantel-Haenszel odds ratio (weighted by sex and pediatric/adult) of a salmonella case reporting "any symptom" compared to controls was 5.42; 95% confidence interval (CI) 2.18-16.27; and reporting joint symptoms was 4.40; 95% CI: 1.25-19.53. The sex distribution of cases reporting joint symptoms was not significantly different. No medication taken during the salmonella infection was significantly different between the cases who had joint symptoms and those who did not. Four cases (2 adults, 2 children) were considered by the rheumatologist to have symptoms consistent with ReA, 2 of these had been told by a physician that their symptoms were related to their ST infection. CONCLUSION: Cases were more than 4 times more likely to report joint symptoms than controls; and despite the loss of many cases to followup, 6% of all cases were considered to have ReA.     

Reactive arthritis after an outbreak of Yersinia pseudotuberculosis serotype O:3 infection

OBJECTIVE: To determine the occurrence and clinical characteristics of reactive arthritis (ReA) after an outbreak of Yersinia pseudotuberculosis serotype O:3 infection. METHODS: From 15 October to 6 November 1998, a widespread outbreak of Y pseudotuberculosis serotype O:3 occurred in Finland. A questionnaire on musculoskeletal symptoms was mailed to 38 patients with infection confirmed by culture. All patients who reported joint symptoms were interviewed by phone and their medical records of outpatient visits or hospital admission because of recent joint symptoms were reviewed. RESULTS: Thirty three of 38 (87%) patients returned the questionnaire. Reactive musculoskeletal symptoms were reported by 5/33 (15%): four patients (12%) fulfilled the criteria for ReA and one additional patient had reactive enthesopathy. The patients with ReA were adults (age range 40-47 years), whereas the patient with reactive enthesopathy was a 14 year old boy. In all patients with ReA, the arthritis was polyarticular. In addition to peripheral arthritis, other musculoskeletal symptoms included sacroiliitis (one patient), pain in Achilles tendon (one patient), and heel pain (two patients). HLA-B27 was positive in all the three patients tested. In three of four patients with ReA, the duration of acute arthritis was over six months. CONCLUSION: Y pseudotuberculosis serotype O:3 infection is frequently associated with ReA and the clinical picture is severe.     

Campylobacter-triggered reactive arthritis: a population-based study

OBJECTIVE: To study the incidence and clinical picture of Campylobacter-associated reactive arthritis (ReA) and other reactive musculoskeletal symptoms in the population. METHODS: A questionnaire on enteric and extraintestinal, including specifically musculoskeletal, symptoms was sent to 870 consecutive patients with Campylobacter-positive stool culture and 1440 matched controls. Analysis of self-reported musculoskeletal symptoms with clinical examination was performed. RESULTS: Forty-five of the patients (7%) had ReA and eight (1%) had reactive tendinitis, enthesopathy or bursitis. No child had ReA. The arthritis was oligo- or polyarticular, and, in most cases, mild. HLA-B27 was positive in 14% of ReA patients. Of the 45 ReA patients, 37 had C. jejuni and 8 had C. coli infection. No controls had ReA. CONCLUSION: ReA is common following Campylobacter infection, with an annual incidence of 4.3 per 100000. At the population level, acute ReA is mild, more frequent in adults, and not associated with HLA-B27. Besides C. jejuni, C. coli can trigger ReA.     

Reactive arthritis following an outbreak of Campylobacter jejuni infection

OBJECTIVE: To study the occurrence and the clinical picture of musculoskeletal (MSK) complications including reactive arthritis (ReA) following an outbreak of Campylobacter jejuni. METHODS: An outbreak of C. jejuni infection occurred in 2000 in Asikkala, Finland, during which 350 exposed subjects contacted the Municipal Health Centre (MHC). All primary care physicians in the MHC were advised to refer patients with acute MSK complications to the Rheumatism Foundation Hospital (RFH) for a specialist clinical examination, which was performed 相似文献   

Postdysenteric reactive arthritis. A clinical and immunogenetic study following an outbreak of salmonellosis

Following an outbreak of foodborne gastroenteritis caused by Salmonella typhimurium, questionnaires were sent to affected individuals and then to the family physicians of any who experienced extra-enteric complications. Of 260 individuals infected with S typhimurium for whom adequate data were obtained, 19 patients developed joint disease (7.3%). All were men; the mean age +/- SD was 39.3 +/- 1.6 years. Among the 16 patients for whom this information was available, the interval from the onset of diarrhea to the onset of joint pain was less than 7 days in 7, 8-21 days in 2, and greater than 21 days in 7. There was a significantly longer duration of diarrhea in those patients with joint disease (mean +/- SEM 15.2 +/- 2.6 days) than in those without complications (10.0 +/- 1.1 days) (P less than 0.01). The joint disease was monarticular in 3 patients and polyarticular in 16. The joints most commonly affected were the elbow (47%), wrist (47%), knee (42%), low back (32%), and shoulder (32%). Six of the 19 patients had at least 1 extraarticular feature: ocular (5 patients), mucosal (1 patient), urethral (2 patients), or cutaneous (1 patient). Of these 19 patients, 11 were located and agreed to HLA typing. Four were positive for HLA-B27, 6 were HLA-B7 positive, and 1 had HLA-Bw60. Of the 4 B27 positive patients, 3 were DR1 positive; of the 6 B7 positive patients, 5 were DR2 positive.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reactive arthritis attributable to Shigella infection: a clinical and epidemiological nationwide study

OBJECTIVES: To study the incidence and clinical picture of Shigella associated reactive arthritis (ReA) and the arthritogenicity of various Shigella species in the population. METHODS: A questionnaire on enteric and extraintestinal, especially musculoskeletal, symptoms was sent to 278 consecutive patients with Shigella positive stool culture and to 597 controls. Analysis of self reported musculoskeletal symptoms was supplemented with clinical examination of those subjects with recent symptoms. RESULTS: Of the patients, 14/211 (7%) had ReA, and a further 4/211 (2%) other reactive musculoskeletal symptoms (tendonitis, enthesopathy, or bursitis). Of the 14 patients with ReA, all adults, 10 had S sonnei, three S flexneri, and one S dysenteriae infection. HLA-B27 was positive in 36% of the patients with ReA. One control subject had ReA. In the patients with Shigella infection, the odds ratio for developing ReA was 16.2 (95% confidence interval 2.1 to 123.9), p = 0.001. CONCLUSIONS: ReA occurred in 7% of patients after Shigella infection, with an annual incidence of 1.3/1 000 000 in Finland. Besides S flexneri, S sonnei and S dysenteriae can also trigger ReA.     

A comparison of self-reported joint symptoms following infection with different enteric pathogens: effect of HLA-B27

OBJECTIVE: We conducted a case-case comparison study to estimate the attack-rate of reactive joint pain (JPrea) following intestinal infections, and evaluated whether the susceptibility and severity of joint symptoms was associated with the tissue-type HLA-B27. METHODS: Consecutive patients with positive fecal culture for Salmonella, Campylobacter, Yersinia, Shigella, and E. coli were addressed by questionnaires inquiring about gastrointestinal (GI) symptoms and the occurrence of joint pain in a previously healthy joint within 4 weeks after onset of infection. A blood sample was requested for HLA-B27 typing. RESULTS: Of 3146 patients invited, 2105 (67%) responded to the survey questionnaire. The triggering infections were Campylobacter, 1003; Salmonella, 619; E. coli, 290; Shigella, 102; and Yersinia, 91. JPrea was reported by 294 subjects: Campylobacter, 131 (13.1%); Salmonella, 104 (16.8%); Yersinia, 21 (23.1%); Shigella, 10 (9.8%); and E. coli, 28 (9.7%). There was a significant association between severity of gastroenteritis and development of arthralgia (p = 0.001). The odds ratio (OR) for JPrea in an HLA-B27-positive individual was 2.62 (95% CI 1.67-3.93) for the entire group. A significant association between JPrea and HLA-B27 was found for Salmonella, Shigella, and Yersinia; not, however, for Campylobacter and E. coli. HLA-B27-positive patients had a significantly increased risk for severe joint symptoms. CONCLUSION: Our study shows that JPrea after GI infection is positively correlated to severity of GI symptoms. HLA-B27 is not associated with joint pain after Campylobacter. Intestinal E. coli seems to be an arthritogenic pathogen. A significant association between HLA-B27 and severity of joint pain was observed.     

Pathogenesis of reactive arthritis

There is good evidence that bacteria persist in vivo in patients with reactive arthritis (ReA). While Chlamydia seem to hide inside the joint, other areas such as gut mucosa or lymph nodes seem to be more likely places for Salmonella and Yersinia. T-helper (Th) 1 cells secreting cytokines such as IFN gamma and TNF alpha are crucial for an effective elimination of these bacteria. An inhibited Th1-response could be demonstrated in ReA, probably contributing to bacterial persistence. While HLA-B27 is found in only approximately 50% of patients with acute ReA, HLA-B27 seems to be crucial for the development of features typical with chronic spondyloarthropathy, such as sacroiliitis. Among several hypotheses to explain the interaction of bacteria with HLA-B27, the most likely seems to be that until now unknown bacterial or self- antigens were presented by HLA-B27 to CD8(+) T-cells. An important site where the immunopathology takes place seems to be at the insertion of tendons and ligaments at bone. Because antibiotics have failed so far in the treatment of ReA immunomodulatory therapies, based on a better understanding of the pathogenesis, alone or in combination with antibiotics might be an option for the future.     

Reaktive Arthritis

Reactive arthritis (ReA) was first described 100 years ago. It is defined as a sterile joint inflammation following a primary, extra-articular infection often in the form of urethritis or enteritis and less frequently respiratory infection and is characterized by the presence of bacterial antigens or non-culturable bacteria in the joint,. The prevalence is estimated to be 40/100,000 adults, while the incidence is 4-5/100,000. The classic HLA-B27-associated form with asymmetric involvement of the lower extremities and/or the spine is part of the spondyloarthritis concept. The phenomenon of persistence, which will be discussed in detail herein, plays an important role in the pathogenesis of ReA. Up to 30% of patients develop chronic symptoms posing a therapeutic challenge. Combination antibiotic treatment showing a response in up to 63% of patients has recently been proposed. Biologics could represent an alternative therapeutic option for patients showing a severe and highly active disease course.     

High frequency of reactive joint symptoms after an outbreak of Salmonella enteritidis

OBJECTIVE: To study reactive symptoms following an outbreak of Salmonella enteritidis that occurred after a dinner party held January 15, 1999, in Copenhagen, Denmark. An epidemiological study pointed toward a dish of minced raw salmon, in which one of the constituents was unboiled eggs as the likely cause of the outbreak. Remnants of this dish were not available for bacteriological exam. METHOD: All 94 guests and kitchen staff members were mailed a questionnaire about gastrointestinal, joint, and eye symptoms. Nonrespondents were contacted by telephone. Thirty-five individuals delivered blood samples for serological analysis mean 90 days (range 60-186) after the exposure. RESULTS: Answers were obtained from all participants and 91 were regarded as Salmonella exposed. Male/female ratio was 40/51, mean age 49 years. Fifty-two reported diarrhea (57%), 49 abdominal pain (54%), 33 fever (36%), and 12 vomiting (13%). Eight (9%) delivered stool samples, and all were positive for S. enteritidis. Seventeen fulfilled predefined criteria of reactive arthritis/arthralgia (ReA), and of these 13 had had enterocolitis. Joint pain from knees and ankles was most frequently reported. The mean duration of diarrhea among the patients reporting joint symptoms was 7.5 days, while in the group of patients with enterocolitis without joint symptoms it was 4.1 days (p = 0.00047). Three participants, all from the ReA group, reported ocular redness and irritation compatible with conjunctivitis. Although there was a trend to higher IgG anti-Salmonella antibody levels among the patients with ReA the difference was not significant. CONCLUSION: Reactive joint symptoms after food-borne Salmonella infection may be more frequent than previously thought. The duration of diarrhea is strongly correlated with the occurrence of joint symptoms.     

Human immunodeficiency virus related reactive arthritis in Zambia

OBJECTIVE: To characterize the clinical, radiological, and diagnostic features of reactive arthritis (ReA) in indigenous Black Zambians with human immunodeficiency virus (HIV) infection. METHODS: Consecutive patients attending an arthritis clinic over a 5-year period were studied prospectively. Those who satisfied diagnostic criteria for ReA were analyzed. RESULTS: In total, 170 patients satisfied the ESSG criteria for ReA; 71 (45 men, 26 women) had one or more extraarticular manifestations; 30% had enteroreactive and 14% uroreactive disease. Only 59% of patients had the diagnostic features of ReA at presentation. The initial diagnosis was undifferentiated spondyloarthropathy (uSpa) in 20%, other ReA in 14%, and "arthritis alone" in 7%. Of 65 (42 men, 23 women) patients tested, 94% were HIV-positive (91% men, 100% women). In those with HIV, the arthritis was predominantly polyarticular, lower limb-predominant, and progressive; 58% of 33 with persistent disease had erosions of foot and/or hand joints (average disease duration, 24.4 mo); 6 of 10 showed early radiological spine or sacroiliac joint changes (average duration 47.7 mo). Anterior uveitis occurred in 33% of patients, while keratoderma blenorrhagicum and stomatitis occurred in 14.3% and 9.5%, respectively, of patients with enteroreactive ReA. Uroreactive ReA was more common in women. There were no significant differences in the clinical, diagnostic, or radiographic features between men and women or between those with or without a known preceding trigger. CONCLUSION: HIV associated ReA in Black Zambians frequently follows an accelerated course with a strong tendency to relapse, develop early erosions and joint deformity, and become chronic. The clinical, diagnostic, and radiographic features are indistinguishable from those described in the conventional (HLA-B27 related) disease, although our HIV-positive patients have a high overall frequency of uveitis, keratoderma, and onycholysis.     

Determinants of synoviocyte clearance of arthritogenic bacteria

OBJECTIVE: Persistence of intracellular organisms may play a critical role in the initiation and perpetuation of synovitis in reactive arthritis (ReA). We investigated factors that may influence local clearance of arthritogenic pathogens in ReA. METHODS: We studied 11 HLA-B27 positive patients with spondyloarthropathies and contrasted these patients with 6 HLA-B27 negative control patients with rheumatoid arthritis or osteoarthritis. We employed an ex vivo system in which human synoviocytes derived from patients with ReA are cocultured with arthritogenic pathogens, and intracellular clearance is measured by quantitating colony-forming units over time. RESULTS: The clearance kinetics of the organisms bore no relationship to the HLA-B27 status of the patient. Clearance of S. typhimurium over a 10 day period was accompanied by a progressive rise in nitric oxide (NO) production, but this appeared not to be rate-limiting, since (1) clearance kinetics were comparable between high versus low NO-producing synoviocytes; and (2) L-NMMA inhibition of NO production did not alter clearance kinetics of S. typhimurium. Interferon-g (IFN-g) was observed to have a small but measurable effect on bacterial clearance. In certain patients with ReA there was a paradoxical stimulatory response to IFN-g, in which the addition of IFN-g was accompanied by an increase in intracellular bacteria. This effect was found to be attributable to IFN-g mediated suppression of NO production in these cells. This pattern was not observed in B27 negative synoviocytes. CONCLUSION: Intracellular persistence of arthritogenic organisms may contribute to the cellular basis of ReA, but the molecular basis of the bacteriocidal pathways in synoviocytes has not been fully resolved. Our findings indicate that a direct effect of HLA-B27 on these events is unlikely, but that alterations in cytokine response profiles may play a contributory role. Characterizing these mechanisms holds the promise of more specific therapeutic interventions in this disease.     

Invasion of Salmonella into human intestinal epithelial cells is modulated by HLA-B27

OBJECTIVE: To investigate the influence of the major histocompatibility complex (MHC) class I molecule HLA-B27 on (i) the invasion of Salmonella and Yersinia into human intestinal epithelial cells, (ii) the survival of intracellular Salmonella in these cells, and (iii) the production of certain inflammatory cytokines by the cells after Salmonella infection. METHODS: The human intestinal epithelial cell line Henle-407 was transfected with HLA-B27 DNA. These cells and HLA-B27-negative control cells were infected with Salmonella or Yersinia, and viable intracellular bacteria were determined as colony-forming units. Cytokine production was assayed with ELISA. RESULTS: Salmonella invaded HLA-B27-positive Henle cells in higher numbers than HLA-B27-negative control cells. However, HLA-B27 did not affect the invasion of Yersinia or the survival of the intracellular bacteria in these intestinal epithelial cells. Salmonella infection induced production of interleukin-8 (IL-8), IL-6 and monocyte chemotactic protein 1 (MCP-1) by Henle cells that was not affected by HLA-B27 in a specific way. CONCLUSIONS: These findings suggest that HLA-B27 enhances the invasion of Salmonella into intestinal epithelial cells. The interaction between bacteria and intestinal epithelial cells plays an important role during the early phases of ReA. HLA-B27-linked modulation of Salmonella invasion may lead to an increased load of Salmonella in intestinal tissue and thus increased susceptibility to reactive arthritis.     

Distribution of HLA-B27 and its alleles in patients with reactive arthritis and with ankylosing spondylitis in Tunisia

The purpose of the present study is to investigate the frequency of HLA-B27 and its alleles in reactive arthritis (ReA) and in ankylosing spondylitis (AS) in Tunisia. HLA-B27 alleles were typed by PCR amplification with sequence-specific primers. We studied 17 patients with ReA associated with urethritis or with gastrointestinal infection; 42 HLA-B27-positive patients with AS and 100 healthy controls. Eleven ReA patients (67.7%) were HLA-B27 positive. There was an increased frequencies of HLA-B27 (P = 7.76 × 10⁻¹², OR = 59.30) and a moderate increase of HLA-B51 (P = 0.015; OR = 4.91) alleles in ReA patients when compared with healthy controls. Four B27 subtypes were identified: B*2702, 05, 09 and B*2712. The distribution of these alleles in the ReA patients was 37.5% for B*2702 and B*2705. Only these two subtypes were detected in 18 (42.8%) and 24 (57.1%), respectively, of the AS patients. B*2709 and B*2712 were relatively rare in ReA patients and were identified in one case each. Our results showed a restricted number of HLA-B27 subtypes associated with ReA and AS. B*2702 and 2705 were common in ReA and AS patients.     

Human lymphocyte response to selected infectious agents in Reiter's syndrome and ankylosing spondylitis

Summary Reiter's syndrome (RS) and idiopathic ankylosing spondylitis (AS) have been associated with certain infections and the histocompatibility antigen HLA-B27. The proliferative responses of peripheral mononuclear cell preparations from 18 patients with RS, 6 with AS, and 22 unaffected subjects were studied toward Shigella flexneri, Salmonella typhimurium, Yersinia enterocolitica, Klebsiella pneumoniae, and Chlamydia trachomatis. Although RS, AS, and HLA-B27-positive normal subjects had generally higher mean responses than HLA-B27-negative controls, no significant differences were demonstrated. Using a chromium release assay, the cytotoxicity of an HLA-B27 antiserum was not altered by preincubation of lymphocytes with these organisms for several individual subjects in each study group.     

Outer membrane protein of salmonella is the major antigenic target in patients with salmonella induced reactive arthritis

OBJECTIVE: We previously reported that Salmonella typhimurium was the triggering agent in one-third of our patients with sporadic enteric reactive arthritis (ReA) and undifferentiated spondyloarthropathy (uSpA). The antigens recognized by the synovial T cells in Salmonella induced ReA are not known. We investigated the immunodominant antigens in Salmonella ReA. METHODS: Synovial fluid mononuclear cells (SFMC) from 53 patients with ReA/uSpA were cultured with crude lysate of S. typhimurium. In 20 patients, the triggering agent was found to be Salmonella (stimulation index, SI, > 2.5). For cell fractionation of S. typhimurium, the sonicated crude lysate was separated by ultracentrifugation into a cytoplasmic supernatant (CYT) and membrane pellet (OMP). The CYT was further separated on SDS-PAGE and blotted onto nitrocellulose membrane for proliferation assays. SFMC from 20 patients with Salmonella ReA/uSpA were stimulated with OMP, CYT, and cytosolic fractions of S. typhimurium, and proliferation was measured by thymidine incorporation. Quantitation of antigen-specific cells in SF was by intracellular interferon-g staining in 7 patients and paired peripheral blood (PB) in 5 patients after stimulation with crude Salmonella lysate, CYT, and OMP. RESULTS: Out of 20 patients with Salmonella ReA/uSpA, the SFMC showed a significant proliferation to OMP in 19 patients and CYT in 17 patients. The median SI of OMP (8.2, range 2.8-52.5) was significantly higher (p < 0.0005) than for the CYT (4.9, 2.7-18.8). Fifty percent of the patients showed proliferative response to cytosolic fractions of < 60 kDa. The mean antigen-specific T cell frequency was also higher with OMP (0.68% +/- 0.59%) than CYT (0.53% +/- 0.62%) but this was not statistically significant. Compared to PB, the OMP-specific cells were 7.5 times more numerous in the SF (p < 0.05). CONCLUSION: The cellular immune response in Salmonella ReA/uSpA is directed predominantly against the OMP and low molecular weight proteins in the cytosolic fraction.