BPI-ANCA is found in reactive arthritis caused by Yersinia and Salmonella infection and recognise exclusively the C-terminal part of the BPI molecule

OBJECTIVE

To examine the prevalence, binding sites and functional interactions of antineutrophil cytoplasmic autoantibodies (ANCA) against the bactericidal/permeability increasing protein (BPI) in reactive arthritis (ReA).

METHODS

Sera were analysed for the occurrence of ANCA by indirect immunofluorescence microscopy (IIF) and ELISA. Binding sites were determined using BPI, lipopolysaccharid binding protein (LBP), and fusion proteins of both proteins in ELISA. In addition, the effect of antibodies on the antibiotic activity of BPI was examined.

RESULTS

BPI-ANCA was found in patients with Yersinia- and Salmonella-triggered ReA and directed against the C-terminal portion of BPI. Goat anti BPI antibodies recognising this part inhibited the antibiotic activity of BPI in vitro.

CONCLUSION

BPI-ANCA was associated with ReA triggered by Salmonella and Yersinia infection. Directed against the C-terminal part of BPI, it can potentially inhibit its antibiotic activity and might be useful to identify patients with infectious bowel disease prone to extraintestinal sequelae.

HLA haplotype analysis in Finnish patients with rheumatoid arthritis

OBJECTIVE

To further characterize the HLA gene products that play an important role in the pathogenesis of rheumatoid arthritis (RA).

METHODS

One hundred thirty-four haplotypes from 67 Finnish RA patients and 77 control haplotypes were analyzed for HLA-DRB1 loci, associated alleles of the HLA-DQB1 locus, alleles of the type 2 transporter-associated antigen processing (TAP2) genes, and HLA-B27. In addition, a panel of microsatellite markers within the HLA class I and class III regions was studied.

RESULTS

The frequency of HLA-DRB1*04 in the haplotypes of RA patients was found to be 34% (45 of 134) compared with 14% (10 of 72) in control haplotypes (P = 0.004). The frequency of HLA-DRB1*13 was decreased in RA haplotypes (4%, or 5 of 134) in contrast to control haplotypes (24%, or 17 of 72) (P = 0.000031). The decrease in DRB1*13 was not secondary to the increase in DRB1*04, since it was also found among DRB1*04-negative haplotypes (P < 0.001). The DRB1*13-associated DQB1*0604 allele was similarly decreased in RA haplotypes (P = 0.025). The TAP2I allele of I/J dimorphism was increased in RA patients (85%, or 114 of 134) as compared with controls (69%, or 49 of 71) (P = 0.011). Of the tumor necrosis factor (TNF) microsatellite alleles, TNFa6 and TNFb5 were found to be increased in RA haplotypes (for a6 27% versus 5% in controls [P = 0.00043], and for b5 43% versus 26% in controls [P = 0.037]).

CONCLUSION

Both protection-associated and susceptibility-associated alleles can be found among HLA class II genes, and the results suggest that loci outside DR/DQ may contribute to the pathogenesis of RA.

Increase in T-cell subsets of oral mucosa: a late immune response in patients with treated coeliac disease?

BACKGROUND AND AIMS

In coeliac disease, the gut involvement is gluten-dependent. Following the introduction of a gluten-free diet, inflammatory cell infiltration decreases in the small intestinal mucosa. Our hypothesis was that the oral mucosa might mirror the changes found in coeliac disease similarly to the mucosa of the small intestine. Thus, the number of inflammatory cells in the oral mucosa would decrease in patients with coeliac disease on a gluten-free diet.

METHODS

The distribution CD45RO+ and CD3(+) T cells, T-cell subpopulations (CD4(+), CD8(+), T-cell receptor (TCR)alpha beta+ and TCR gamma delta+ cells) and HLA DR expression were studied in the buccal mucosa of 15 untreated and 44 gluten-free diet treated coeliac disease patients, and of 19 controls. All 15 patients with untreated coeliac disease were immunglobulin (Ig)A endomysial antibody positive and all 44 patients on gluten-free diet except one were endomysial antibody negative, as were all control subjects.

RESULTS

Untreated coeliac disease patients did not differ from controls in the densities of CD45RO+ cells, CD3(+) cells or of T-cell subsets. In contrast, in treated coeliac disease patients, a significant increase in the numbers of mast cells, CD3(+) and CD4(+) lymphocytes was found in the lamina propria of oral mucosa as compared with patients with untreated coeliac disease and controls. The increase in CD3(+) T cells was in part owing to an increase in lymphocytes expressing no TCR. No differences were found in the expression of human leucocyte antigen (HLA) DR in the epithelium or in the lamina propria in the patient groups studied or in the controls. In treated coeliac disease patients only a few TCR gamma delta+ T cells were found intraepithelially and in the lamina propria, but these cells were not detected in the lamina propria of oral mucosa of patients with untreated coeliac disease or in the controls.

CONCLUSIONS

The infiltration of T cells into oral mucosa was increased in treated coeliac disease patients in spite of adherence to a gluten-free diet. Because the CD3(+) T cell count was higher than those of the TCR alpha beta+ and TCR gamma delta+ T cells, there must be other cells involved, probably natural killer (NK) cells. The increase in T-cell subsets in the treated coeliac disease patients seems not to result from poor dietary compliance, but might occur as a late immune response in coeliac disease and reflect chronic immunologic stimulation followed by regeneration of memory T cells.

Prolonged arthritis associated with sindbis-related (Pogosta) virus infection

OBJECTIVE

A follow-up study of musculoskeletal symptoms after Pogosta virus infection.

METHODS

Twenty-six patients with earlier serologically confirmed Pogosta disease were examined. Ultrasonography of affected joints was performed in patients who had chronic musculoskeletal symptoms. Serum antibodies against Sindbis virus were determined. The patients were typed for HLA-DR and B27. Efforts were made using the polymerase chain reaction to demonstrate the virus.

RESULTS

Only 50% of the patients were symptomless 2.5 yr after onset of Pogosta disease. Three patients had fibromyalgia, six had occasional arthralgia and two had chronic arthritis.

CONCLUSIONS

The epidemiology of Pogosta disease is changing and practitioners should be better aware of it. Pogosta virus infection may lead to chronic musculoskeletal discomfort and arthritis.

Local challenge on oral mucosa with an alpha-gliadin related synthetic peptide in patients with celiac disease

OBJECTIVE

Gluten-derived peptides (e.g., amino-acids 31-49 of alpha-gliadin) have been shown to cause changes typical of celiac disease in the gut. Gluten-derived peptides have mostly been used in in vitro studies. The easiest access to the gastrointestinal system may be the mouth. In the present study we were interested to see whether a synthetic peptide corresponding to amino-acids 31-49 of alpha-gliadin could induce inflammatory changes in the oral mucosa after a local challenge in celiac disease patients.

METHODS

The challenge was made by injecting the peptide solution at a concentration of 10 microg/ml submucosally into the oral mucosa of 10 celiac disease patients after a gluten-free diet (GFD) and 12 healthy control subjects. B and CD45RO+ T cells, mast cells, CD3+, CD4+, CD8+ lymphocytes, and alphabeta and gammadelta T-cell receptor-bearing (TcR alphabeta, TcR gammadelta) lymphocytes were counted and HLA DR expression was determined. The expression of CD25 and Ki-67 antigen was also examined.

RESULTS

The peptide significantly increased the total number of T cells in the lamina propria of the celiac disease patients. The expression of T-cell activation marker CD25 (IL-2 receptor), but not that of cell proliferation marker Ki-67, was also significantly increased in the lamina propria after peptide challenge. Such a reaction was not observed in the controls. The numbers of CD3+ and CD4+ T cells in the lamina propria were also increased in celiac disease patients after the challenge. The count of TcR gammadelta+ cells was very small in the oral mucosa in celiac disease and showed no increase when the oral mucosa was challenged with the peptide. The expression of HLA DR staining was enhanced after the submucosal peptide challenge in celiac disease; however, the difference was not statistically significant.

CONCLUSIONS

The results show that in the celiac disease patients after the peptide challenge the oral mucosal lamina propria responds with a nonproliferative increase of lymphocytes. Thus, submucosal challenge with the peptide 31-49 can be used as an aid in the diagnosis of celiac disease. However, further studies with optimized methodology, including various concentrations of the peptide, adjuvants, other peptides, etc., are warranted, especially because the oral mucosa provides the easiest access to an in vivo peptide challenge in celiac disease.

Reactive arthritis

During the past year, no big advances were reported in understanding the pathogenesis or treatment of reactive arthritis (ReA). The need for generally accepted diagnostic criteria has become a central issue. Regarding pathogenesis, attention has been drawn to a similarity between ReA and the experimental antigen-induced arthritis. Molecular mechanisms of the HLA-B27-associated pathogenesis have remained, in spite of intensive research, so far a mystery. It is apparent that antibiotics have no effect on the fully developed reactive arthritis, with the exception of patients with Chlamydia-triggered ReA, who might benefit from a course of antibiotics.

Effect of a three month course of ciprofloxacin on the outcome of reactive arthritis

BACKGROUND

Treatment of reactive arthritis (ReA) with antibiotics has so far remained controversial. Eradication of the causative microbe appears logical, but short term antibiotic treatment has no beneficial effect on the outcome of ReA.

OBJECTIVE

To evaluate the effect of a three month course of ciprofloxacin on ReA.

METHODS

In a randomised, double blind, placebo controlled trial, between December 1992 and February 1996, 71 patients with acute ReA triggered by a gastrointestinal or a urogenital infection were randomly assigned to receive ciprofloxacin 500 mg or placebo twice daily for three months. Patients were assessed at study entry, at 6 weeks, 3 months, 6 months, and 12 months. Sixty two patients were valid for the efficacy analysis. The primary outcome measures were erythrocyte sedimentation rate, number of swollen joints, patients self assessment, and complete recovery.

RESULTS

Adverse events were mostly mild and occurred in both treatment groups. There were no statistically significant differences in any of the primary or secondary efficacy variables between the study groups at baseline or during the 12 month follow up. All primary outcome measures indicated that the condition of the patients improved during the study.

CONCLUSION

Both groups tended to recover. Ciprofloxacin, given as a three month course, had no advantage over placebo treatment.

Local challenge of oral mucosa with gliadin in patients with coeliac disease

In coeliac disease, gluten-containing diet challenges over many years are sometimes required for diagnosis, especially if the initial diagnosis was equivocal. The rectal gluten challenge has been proposed to simplify coeliac disease diagnosis. We were interested in studying whether the oral mucosa could be used for local challenge with gliadin as an aid in finalizing the diagnosis of coeliac disease. The study groups consisted of 37 treated coeliac disease patients and 10 controls. The challenges on the oral mucosa were performed either supramucosally with gliadin powder (coeliac disease patients) or by submucosal injection of dissolved gliadin (10 microg/ml) (coeliac disease patients and controls). A control challenge with submucosal gliadin solvent was made in the coeliac disease patients. B and T cells, mast cells and T cell subsets were counted and HLA-DR expression was determined. Biopsies were taken from each provoked area 24 h post-challenge. A significant increase in the number of CD4+ lymphocytes in the lamina propria (observed in 27/37 patients), but a decrease in the number of mast cells was observed in treated coeliac disease patients after submucosal challenge with gliadin. Following supramucosal challenge with gliadin the counts of intraepithelial CD4+ (in 25/37 patients) and CD8+ T cells (in 27/37 patients) increased significantly and the number of CD4+ T cells in the lamina propria was also significantly increased. Control subjects were tested by submucosal gliadin challenge and no significant changes in the number of cells were observed. HLA-DR expression did not show increased positivity in coeliac disease patients on submucosal challenge. For the first time the oral mucosa has been used for immunological testing and shown to react to gliadin challenge in coeliac disease patients. Recruitment of T cells upon submucosal gliadin challenge occurred towards the lamina propria, whereas it occurred towards the epithelium in supramucosal gliadin challenge. The numbers of T cells increased in the lamina propria after submucosal challenge. The results suggest that local oral challenge with gliadin may be used as a diagnostic method in coeliac disease; however, further studies in untreated coeliac disease patients are needed to evaluate the usefulness of this method.

Immunogenetic differences between patients with familial and non-familial rheumatoid arthritis

OBJECTIVE

To search for possible immunogenetic differencies between the patients with familial and non-familial rheumatoid arthritis (RA).

METHODS

The study compared 129 familial RA patients with 217 non-familial patients for the frequencies of HLA-DR antigens including DR4 subtypes, DR4-DQB1*0301 and DR4-DQB1*0302 haplotypes and HLA-B27 antigen as well as the age of disease onset and existence of rheumatoid factor or joint erosions.

RESULTS

Two major differences between familial and non-familial groups were found: firstly, familial RA patients had increased frequency of HLA-DR4 as compared with the non-familial RA group (68.2 v. 54.8%; p = 0.019). Secondly, the mean age at onset of RA was significantly lower in the familial than in the sporadic RA patients (42.0 v. 46.5 years; p = 0.0020) and the difference still remained when the DR4 positive and negative subgroups were compared separately.

CONCLUSION

These results confirm the more prominent association with HLA-DR4 in familial than in the non-familial cases and suggest that accumulation of HLA risk genes may, at least partly, explain the familial occurrence of the disease. Other susceptibility genes may also be concentrated in multiplex case families as suggested by an earlier age at the onset of RA in both HLA-DR4 positive and negative familial patients.

Bone mineral density of the lumbar spine in patients with advanced rheumatoid arthritis. Influence of functional capacity and corticosteroid use

We investigated factors that are related to generalized osteoporosis in advanced rheumatoid arthritis (RA). In this cross-sectional study we measured trabecular bone mineral density (BMD), by quantitative computerized tomography (QCT), in the lumbar spine of 57 patients with RA, most of whom were premenopausal women. In our material, 27 out of 57 patients (47%) had BMD <-1 SD expressed as Z-score and five patients had suffered from fractures. Our study shows that a cumulative corticosteroid dose (r = -0.41, p<0.010) and functional impairment (r = -0.37, p<0.050) were negatively related to spinal BMD, while daily intake of calcium correlated positively on BMD (r = 0.37, p<0.010). Our results indicate that low BMD is common in patients with advanced RA and it is associated with long-term corticosteroid use. Thus, in clinical practice we have to consider the benefits and harms of corticosteroid treatment and preventive therapy to osteoporosis.

Two forms of reactive arthritis?

Inflammatory arthritides developing after a distant infection have so far been called reactive or postinfectious, quite often depending on the microbial trigger and/or HLA-B27 status of the patient. For clarity, it is proposed that they all should be called reactive arthritis, which, according to the trigger, occurs as an HLA-B27 associated or non-associated form. In addition to the causative agents and HLA-B27, these two categories are also distinguished by other characteristics. Most important, HLA-B27 associated arthritis may occur identical to the Reiter's syndrome with accompanying ureteritis and/or conjunctivitis, whereas in the B27 non-associated form this has not been clearly described. Likewise, only the B27 associated form belongs to the group of spondyloarthropathies.

Salivary antigliadin and antiendomysium antibodies in coeliac disease

The definitive diagnosis of coeliac disease is based on typical changes in the small intestine biopsy specimens. To screen individuals for coeliac disease serum IgA and IgG antigliadin (AGA), IgA antireticulin (ARA) and IgA antiendomysium (EmA) antibodies are used. The aim of this study was to investigate whether these antibodies can also be detected in saliva as diagnostic markers of coeliac disease. The study population comprised 30 patients with coeliac disease treated with a gluten-free diet, 14 patients with untreated coeliac disease and 13 healthy control subjects. Sera and saliva were tested simultaneously for the presence of IgA and IgG AGA and IgA EmA. None of patients studied had a selective IgA deficiency. There was no significant difference in salivary IgA AGA levels between the three groups tested and there was no correlation between the individual serum and salivary values of IgA AGA. Salivary IgG AGA levels were very low or undetectable. Serum IgA AGA showed a low sensitivity (36.4%) to detect an untreated patient with coeliac disease. All salivary samples, regardless of the study group were negative for IgA EmA. Serum IgA EmAs were universally detected in the sera of patients with newly diagnosed coeliac disease and also in the sera of five of 30 patients with treated coeliac disease. No IgA EmA was detected in the sera of controls. None of the patients studied had a selective IgA deficiency either. Serum IgA EmA is the most sensitive, and IgA and IgG AGA are good indicators for coeliac disease, but salivary IgA or IgG AGA and salivary IgA EmA are not helpful for the diagnosis or follow-up of coeliac disease patients.

Sustaining and improving working capacity--programme description and two years follow-up

In 1991 the Social Insurance Institution Rehabilitation Act introduced a working capacity sustaining and improving training programme (TYK). The goal of this programme is to sustain the physio-psycho-social competences of older workers and employees by creating a chain of in-house rehabilitation phases and training phases at the workplace. We describe the programme in its early state of implementation. Two years after entering the programme 17 patients were working, six were on sick leave, three were out of work, 16 were on pension, and six patients could not be retrieved.

Tumour necrosis factor microsatellites in reactive arthritis

The purpose was to study tumour necrosis factor (TNF)-a, -b and -c microsatellites as potential new susceptibility markers for reactive arthritis (ReA). Fifty-nine patients typed for HLA-B27 were studied for frequencies of TNF microsatellite alleles and compared with allele frequencies determined from 285 random haplotypes and 46 healthy HLA-B27-positive controls. TNFa, -b and -c microsatellite sequences were amplified by the polymerase chain reaction, and the size of the product was defined by an automated sequencer. The frequencies of TNFa6 and -c1 alleles were found to be increased in patients with ReA, whereas TNFa11 and -c2 frequencies were decreased as compared to control haplotypes. The increase in the c1 allele in patients with ReA independently from HLA-B27 suggests that it might be a new susceptibility marker for the disease. The association of ReA with other alleles was due to a linkage disequilibrium with HLA-B27.

Pogosta disease: clinical observations during an outbreak in the province of North Karelia, Finland

OBJECTIVE

To characterize the clinical picture of Pogosta disease.

METHOD

The data of 73 patients who had had Pogosta disease in 1981 and who then had been seen by a local physician in North Karelia were analysed.

RESULTS

The main manifestations were fever (23%), rash (88%) and joint symptoms (93%). The joint symptoms in some patients lasted for several months and were severe enough to cause immobilization. The clinical picture was identical in those patients who had a definite serological diagnosis and those who did not have a detectable antibody response.

CONCLUSION

The symptoms of Sindbis virus-induced Pogosta discase consist of fever, rash and joint symptoms, whic may be severe and prolonged.

Oral mucosal changes in coeliac patients on a gluten-free diet

Oral mucosal lesions or dental enamel defects may be the only presenting features of coeliac disease. A series of 128 patients with coeliac disease (CD) on a gluten-free diet (GFD), 8 patients with a newly diagnosed CD, and 30 healthy controls participated in a clinical and histopathological study of their oral mucosa. Oral mucosal lesions occurred in 71/128 GFD-treated CD patients. in 4/8 untreated and in 10/30 controls, and oral symptoms in 85/128, in 6/8 and in 10/30, respectively. Five CD patients had aphthous ulcers. Moderate to severe lymphocytic inflammation occurred in 36/117 and in 14/117 of the biopsy specimens of GFD-treated CD patients, in 1/8 and 2/8 of untreated CD patients, and in 3/30 and in 1/30 of controls, respectively. Intraepithelial T-cells were significantly more frequent in GFD-treated CD patients than in controls. There was no difference between untreated CD patients and controls. In the lamina propria of the GFD-treated CD patients, T-cells were more frequent than in the other groups. Mast cells were significantly more frequent in patients with GFD-treated CD. Nine GFD-treated CD patients had raised serum endomysium IgA antibody titres, although five of them reported to follow a strict GFD. A lack of strict compliance with a GFD may be related to the high prevalence of oral changes and symptoms. In addition, T-cell infiltration in the oral mucosa tends to increase with a longer duration of CD, independent of GFD-treatment. Clinically, it is important to study the oral cavity of patients suspected of having CD where the only clue to the disease may reside, since no less than 66% of the patients in this study had oral symptoms.

TAP2 alleles in inflammatory arthritis

Sixty patients with reactive arthritis (ReA) and 40 with rheumatoid arthritis (RA), were typed for H LA-B27 and class II antigens DR and DQ, and studied for TAP2 gene polymorphism in comparison with 60 healthy controls. TAP2 polymorphisms at positions 379, 565, 665, and 687 were analyzed using amplification refractory system-based PCR and polymorphisms at positions 386 and 651 using oligonucleotide hybridization. The frequency of the TAP2A/A genotype was 30%(12/40) in RA, in contrast to 13% (8/60) in the controls. This genotype was further associated with DRB1*04 positive RA (10/24, 42%, P=0.01), as well as the TAP2A allele (31/48, 65%, P =0.012). Thr/Thr dimorphism at TAP2 position 665 (24/40, 60%, P=0.024) and Stop/Stop dimorphism at TAP2 position 687 (24/40, 60%, P=0.024) were found to be increased in RA patients as compared to controls. When TAP2I/J polymorphism was studied, TAP2J positivity was found associated with the HLA-B27DR4-DQB1*0301-haplotype in ReA patients. 9/12 of these were positive as compared to 20/60 in random controls (P=0.010). Polymorphisms of the TAP2 gene were found to be associated with subgroups of RA and ReA patients with disease associated markers (e.g. TAP2A in DRB1*04 positive RA, or TAP2J in HLA-B27-DRB1*04-DQB1*0301 positive ReA). These may thus serve as additional markers of specific haplotypes associated with susceptibility to inflammatory arthritis.

Out-of-hours utilization in primary and secondary care. A favourable experience in a Finnish health centre

OBJECTIVE

To clarify whether out-of-hours health centre visits and referrals to hospital are equally distributed in the three different duty models being used for health care in southwestern Finland.

DESIGN

A medical audit of 2926 health centre visits and 223 referrals to hospitals by general practitioners (GPs) on duty. The duty models were formed on the basis of a possibility to utilize a local health centre during nights and weekends. Two-month follow-up period.

SETTING

Primary health care. Population 46438.

MAIN OUTCOME MEASURES

Out-of-hours visits to health centres and referrals to hospital, and the effect of age and duty model on referrals and visits.

RESULTS

Patients over 64 years of age received most of the referrals although they visited the health care centre less frequently than the 0-14 year-olds (p < 0.001). The people who had an opportunity to utilize their local health centres visited more during out-of-hours than those who did not have this opportunity (p < 0.001).

CONCLUSIONS

The health centre visits were not equally distributed in the three examined duty models. The over 64 year-olds in particular had the least visits and the most referrals.

Salivary carbonic anhydrase VI concentration and its relation to basic characteristics of saliva in young men

Two successive saliva samples were collected under strictly standardized conditions from 209 healthy, selected male soldiers prior to and after breakfast in the morning and were assayed for carbonic anhydrase (CA) VI concentrations using a specific time-resolved immunofluorometric assay. Salivary secretion rates, pH and buffer capacity pH values, and amylase activity levels were also determined. CA VI concentrations correlated positively to salivary secretion rates and amylase activity levels. By contrast, no significant correlation was seen between CA VI concentrations and pH or buffer capacity pH values, nor between amylase activity levels and salivary secretion rates, pH or buffer capacity pH values. The smokers had unaltered salivary secretion rates, CA VI and amylase activity levels, but lower salivary pH and buffer capacity pH values than the non-smokers. Present results suggest that salivary CA VI is not directly involved in the regulation of pH in saliva.

Different course of reactive arthritis in two HLA-B27 positive brothers with fatal outcome in one

During an outbreak of Yersinia pseudotuberculosis III, one of two HLA-B27 positive brothers developed reactive arthritis (ReA), mild at first, but later severely destructive and ultimately fatal. The reactivation of ReA was possibly triggered by an oral polio vaccine. The cause of death was severe secondary amyloidosis. The other brother was exposed to the same Y. pseudotuberculosis strain but did not develop any disease during or after the outbreak. However, he later developed ReA due to a Salmonella infection, with a benign course.

Reactive arthritis

The complex interactions between the triggering microbe and the defense mechanisms of the host in reactive arthritis have been studied in several laboratories around the world, and interesting observations have been made. Research has also focused on the mediators in the inflammatory process in joints, and these results are helping to slowly build a comprehensive picture about the pathogenetic process in reactive arthritis. For the practicing clinician, some important new findings have emerged. It is known that asymptomatic urogenital infections are quite common as a trigger of reactive arthritis. More aggressive treatment, including disease-modifying drugs as used in the therapy of rheumatoid arthritis, is becoming accepted. The value of antibiotic treatment is being studied, but final conclusions will not be made for perhaps a few years.

Experimental Yersinia-triggered reactive arthritis: effect of a 3-week course of ciprofloxacin

Lewis rats were injected i.v. with live Yersinia enterocolitica, resulting in 1-2 weeks in an arthritis greatly resembling human reactive arthritis. Starting on day 3, 5, 10 or 13 after the bacterial inoculation, the rats were treated for 3 weeks with 20 mg/kg/day of ciprofloxacin. The development of arthritis was completely prevented if the antibiotic treatment was started on day 3. In a group of rats treated with ciprofloxacin from day 5 onwards, 2/14 rats already showed mild arthritis at the time when the treatment was started. Antibiotic treatment cured the arthritis of these rats as well as that of one additional individual in this group which developed arthritis. No later exacerbations occurred. If the antibiotic treatment was started on day 10 or 13, i.e. at the time of well-developed arthritis, no effect on arthritis was observed; rather, increased faecal excretion of Yersinia occurred following the antibiotic treatment. We conclude that experimental Yersinia reactive arthritis can be cured by antibiotics introduced at an early phase of arthritic development. Regarding acute human enterogenic arthritis, the decision on antibiotic treatment is not a straightforward matter. Our experimental results indicate that the earlier the treatment is started, the better the result, whereas late treatments seem to favour bacterial persistence.