Decreased epithelial cytokine responses in the duodenal mucosa of Helicobacter pylori-infected duodenal ulcer patients

The role of Helicobacter Pylori and laryngopharyngeal reflux in recurrent tonsillitis

OBJECTIVES

To detect Helicobacter Pylori [HP] in tonsillar tissue of recurrent tonsillitis cases and assess the possible role of Laryngopharyngeal reflux [LPR] in tonsillar HP infection.

METHODS

A prospective study was done on the cited subject in a sample size of 50 paediatric patients [Age group: 6-18 years] suffering from recurrent tonsillitis. LPR was diagnosed by Reflux Symptom index [RSI] and Reflux Finding score [RFS]. A score of more than 7 and 13 was regarded as significant for RFS and RSI respectively. Patients with both scores significant were regarded to be suffering from LPR. Tonsillar specimen after tonsillectomy were subjected to urease test, histopathology [ Modified Giemsa Staining] and culture to detect HP. A minimum of two positive tests of the mentioned three were taken as gold standard to diagnose colonization of HP. Tabulated data was statistically analysed.

RESULTS

We recorded an incidence of 9% [18 cases] for LPR in recurrent tonsillitis. No case of HP colonization of tonsils was detected in this case series, even in patients of LPR.

CONCLUSION

We conclude that tonsils are not an extra gastric reservoir of HP. In addition, there is no aetiological relationship between recurrent tonsillitis and HP. And lastly, LPR is not a significant factor for colonization of tonsils by HP.

Changes in the severity of gastric mucosal inflammation associated with Helicobacter pylori in humans coinfected with intestinal helminths

BACKGROUND

Though a few studies in animal models suggest that intestinal helminths (IH) favorably affect evolution of gastritis associated with Helicobacter pylori (H. pylori) the studies supporting this concept in humans are only a few and are based on serological data.

METHODS

To evaluate the possible influence of IH on the human gastric mucosa, three groups of Venezuelan adults with gastropathy (endoscopically diagnosed) were studied: H. pylori-/IH- (n = 17), H. pylori+/IH- (n = 18), and H. pylori+/IH+ (n = 11). Histological analysis (hematoxylin-eosin) and immunohistochemical staining (peroxidase) for cytokines interleukin-1beta (IL-1β), tumor necrosis factor alpha (TNF-α), gamma interferon (IFN-γ), and interleukin 4 (IL-4) were undertaken in gastric antral biopsies.

RESULTS

Expression of the four cytokines was detected in all individuals in varying degrees, but proinflammatory cytokines were expressed in a higher degree in the H. pylori+/IH- group, mainly IL-1β (Th1-dominant immune response), associated with a higher degree of both histological inflammation and gastric cancer risk index (GCRI), as compared to the H. pylori-/IH- group. In contrast, an increased expression of IL-4 and a reduced expression of proinflammatory cytokines (Th2-dominant response), plus the tendency to a lower degree of mononuclear infiltration, mucosal atrophy in gastric corpus, and GCRI, were evidenced in the coinfected group.

CONCLUSIONS

The findings of the present study is perhaps the first histological evidence of a possible modulatory effect of IH on the gastric mucosal inflammatory response due to H. pylori infection in humans.

Altered cytokine expression in Helicobacter pylori infected patients with bleeding duodenal ulcer

OBJECTIVE

Peptic ulcer disease is a condition in which an important role has infection with H. pylori. The most common complication of peptic ulcer is bleeding. The presence of H. pylori triggers local and systemic cytokine signaling which may affect processes such as healing, gastric or duodenal rupture, and carcinogenesis. In this study, we examined the concentrations of IL-1β, IL-6, IL-10, TNF, TGF-β and IL-17A in serum by enzyme immunoassay and their mRNA expressions in periulcer biopsies obtained from patients with bleeding peptic ulcer by means of real-time-PCR.

RESULTS

We have shown that pro-inflammatory IL-6 and TNF concentrations in serum were significantly higher in patients who were infected with H. pylori, while the concentrations of TGF-β and IL-17A were significantly lower compared to non-infected subjects. IL-17A expression in periulcer mucosa was significantly higher in patients who were infected with H. pylori, while the expression of other cytokines, there was no significant difference compared to non-infected controls. Considering higher serum concentrations in non-infected subjects and higher IL-17A expression in mucosal tissue of infected patients, our data support the studies that found IL-17A has protective role in eradication of H. pylori infection in infected patients.

Activation of Helicobacter Pylori Causes Either Autoimmune Thyroid Diseases or Carcinogenesis in the Digestive Tract

Helicobacter pylori has been implicated in stimulation of immune system, development of autoimmune endocrinopathies as autoimmune thyroiditis (AT) and on other hand induction of immunosupresion activates gastric and extra-gastric diseases such as gastric ulcer or cancer. It causes persistent lifelong infection despite local and systemic immune response. Our results indicate that Helicobacter pylori might cause inhibition of the specific cellular immune response in Helicobacter pylori-infected patients with or without autoimmune diseases such as AT. We cannot also declare the carcinogenic effect in oropharynx. However the association of any infection agents and cancerogenesis exists. The adherence of Helicobacter pylori expression and enlargement of benign lymphatic tissue and the high incidence of the DNA of Helicobacter pylori in laryngopharyngeal and oropharyngeal cancer is reality. LTT appears to be a good tool for detection of immune memory cellular response in patients with Helicobacter pylori infection and AT. All these complications of Helicobacter pylori infection can be abrogated by successful eradication of Helicobacter pylori.

Exploring alternative treatments for Helicobacter pylori infection

Helicobacter pylori (H. pylori) is a successful pathogen that can persist in the stomach of an infected person for their entire life. It provokes chronic gastric inflammation that leads to the development of serious gastric diseases such as peptic ulcers, gastric cancer and Mucosa associated lymphoid tissue lymphoma. It is known that these ailments can be avoided if the infection by the bacteria can be prevented or eradicated. Currently, numerous antibiotic-based therapies are available. However, these therapies have several inherent problems, including the appearance of resistance to the antibiotics used and associated adverse effects, the risk of re-infection and the high cost of antibiotic therapy. The delay in developing a vaccine to prevent or eradicate the infection has furthered research into new therapeutic approaches. This review summarises the most relevant recent studies on vaccine development and new treatments using natural resources such as plants, probiotics and nutraceuticals. In addition, novel alternatives based on microorganisms, peptides, polysaccharides, and intragastric violet light irradiation are presented. Alternative therapies have not been effective in eradicating the bacteria but have been shown to maintain low bacterial levels. Nevertheless, some of them are useful in preventing the adverse effects of antibiotics, modulating the immune response, gastroprotection, and the general promotion of health. Therefore, those agents can be used as adjuvants of allopathic anti-H. pylori eradication therapy.

Contribution of secretory antibodies to intestinal mucosal immunity against Helicobacter pylori

The natural immune response to Helicobacter pylori neither clears infection nor prevents reinfection. However, the ability of secretory antibodies to influence the course of H. pylori infection has not been determined. We compared the natural progression of H. pylori infection in wild-type C57BL/6 mice with that in mice lacking the polymeric immunoglobulin receptor (pIgR) that is essential for the secretion of polymeric antibody across mucosal surfaces. H. pylori SS1-infected wild-type and pIgR knockout (KO) mice were sampled longitudinally for gastrointestinal bacterial load, antibody response, and histological changes. The gastric bacterial loads of wild-type and pIgR KO mice remained constant and comparable at up to 3 months postinfection (mpi) despite SS1-reactive secretory IgA in the intestinal contents of wild-type mice at that time. Conversely, abundant duodenal colonization of pIgR KO animals contrasted with the near-total eradication of H. pylori from the intestine of wild-type animals by 3 mpi. H. pylori was cultured only from the duodenum of those animals in which colonization in the distal gastric antrum was of sufficient density for immunohistological detection. By 6 mpi, the gastric load of H. pylori in wild-type mice was significantly lower than in pIgR KO animals. While there was no corresponding difference between the two mouse strains in gastric pathology results at 6 mpi, reductions in gastric bacterial load correlated with increased gastric inflammation together with an intestinal secretory antibody response in wild-type mice. Together, these results suggest that naturally produced secretory antibodies can modulate the progress of H. pylori infection, particularly in the duodenum.

Anti-inflammatory and carbonic anhydrase restoring actions of yam powder (Dioscorea spp) contribute to the prevention of cysteamine-induced duodenal ulcer in a rat model

Increased acid output, accompanied with a defective defense system, is considered a fundamental pathogenesis of duodenal ulcer (DU). However, relapse of DU occurs despite proton pump inhibitors and H2 receptor antagonists, hence imposing the enforcement of the defense system. Dried powder of the yam tuber (Dioscorea spp) has been used in traditional folk medicine as a nutritional fortification. We hypothesized that dried-yam powder would prevent DU through improvement of anti-inflammatory actions and carbonic anhydrase (CA) activity. Therefore, we investigated the preventive effects of dried-yam powder against the cysteamine-induced DU and elucidated the underlying mechanisms. Duodenal ulcers were induced in Sprague-Dawley rats by intragastric administration of 500 mg/kg cysteamine-HCl. The dried-yam powder was used as a pretreatment before the cysteamine-HCl. The number and size of DU were measured. The expressions of inflammation mediators were checked in duodenal tissues, and the expressions of CAs and malondialdehyde levels were also examined. Cysteamine provoked perforated DU, whereas dried-yam powder significantly prevented DU as much as pantoprazole and significantly reduced the incidence of perforation. The messenger RNA expressions of cyclooxygenase-2 and inducible nitric oxide synthase were remarkably decreased in the yam group compared with the cysteamine group, and the serum levels of proinflammatory cytokines including interleukin-1β, interleukin-6, and tumor necrosis factor were significantly attenuated in the yam group. Cysteamine significantly decreased the expression of CAs, whereas yam treatment significantly preserved the expressions of CA IX, XII, and XIV. In conclusion, dried-yam powder exerts a significant protective effect against cysteamine-induced DU by lowering the activity of inflammatory cytokines and free radicals and restoring the activity of CAs, except in CA IV.

Detection of Helicobacter pylori in oropharyngeal lymphatic tissue with real-time PCR and assessment of its carcinogenic potential

Helicobacter pylori (HP) is considered a major gastric pathogen with oncogenic potential. The aim of this study was to determine whether HP is present in oropharyngeal lymphoid tissue and whether oropharyngeal HP strains carry virulence factor genes known to be involved in gastric carcinogenesis. The study included 104 subjects (41 patients with tonsillar carcinoma, 38 with chronic tonsillitis and 25 with obstructive sleep apnoea syndrome--OSAS). Detection of specific serum anti-HP antibodies was performed with an ELISA. The presence of HP in tissue was determined by culture and real-time PCR. Detection of virulence factors genes was also performed. Specific antibodies were found in 78.05% of tumour cases, 34.21% of chronic tonsillitis cases, and 72.0% of OSAS cases. The presence of HP in the tissue was detected in 73.91% of tonsillar tumours, 70.0% of tonsillitis cases, and 69.23% of OSAS specimens. The results of the virulence factor gene analysis showed the majority of the s1b (52.4%) and m2 (59.5%) alleles of vacA gene and limited abundance of cagA gene (12.5%). Results confirm that HP may colonise oropharyngeal lymphoid tissue. Oropharyngeal HP colonisation was frequently found in the oropharyngeal cancer group and in patients with benign oropharyngeal diseases. A virulence factor gene analysis showed differences from the predominant strains most commonly found in the stomach. The strains obtained from the oropharynx differed primarily by the lower abundance of the cagA gene and carried the less virulent vacA gene allele combination.

Suppressed Gastric Mucosal TGF-beta1 Increases Susceptibility to H. pylori-Induced Gastric Inflammation and Ulceration: A Stupid Host Defense Response

BACKGROUND/AIMS

Loss of transforming growth factor beta1 (TGF-beta1) exhibits a similar pathology to that seen in a subset of individuals infected with Helicobacter pylori, including propagated gastric inflammation, oxidative stress, and autoimmune features. We thus hypothesized that gastric mucosal TGF-beta1 levels could be used to determine the outcome after H. pylori infection.

METHODS

Northern blot for the TGF-beta1 transcript, staining of TGF-beta1 expression, luciferase reporter assay, and enzyme-linked immunosorbent assay for TGF-beta1 levels were performed at different times after H. pylori infection.

RESULTS

The TGF-beta1 level was markedly lower in patients with H. pylori-induced gastritis than in patients with a similar degree of gastritis induced by nonsteroidal anti-inflammatory drugs. There was a significant negative correlation between the severity of inflammation and gastric mucosal TGF-beta1 levels. SNU-16 cells showing intact TGF-beta signaling exhibited a marked decrease in TGF-beta1 expression, whereas SNU-638 cells defective in TGF-beta signaling exhibited no such decrease after H. pylori infection. The decreased expressions of TGF-beta1 in SNU-16 cells recovered to normal after 24 hr of H. pylori infection, but lasted very spatial times, suggesting that attenuated expression of TGF-beta1 is a host defense mechanism to avoid attachment of H. pylori.

CONCLUSIONS

H. pylori infection was associated with depressed gastric mucosal TGF-beta1 for up to 24 hr, but this apparent strategy for rescuing cells from H. pylori attachment exacerbated the gastric inflammation.

FOXP3-expressing CD4(+) T-cell numbers increase in areas of duodenal gastric metaplasia and are associated to CD4(+) T-cell aggregates in the duodenum of Helicobacter pylori-infected duodenal ulcer patients

BACKGROUND

We have previously demonstrated that Helicobacter pylori infection is associated with an increased number of CD4(+)CD25(high) regulatory T cells in the gastric and duodenal mucosa. In this study, we determined the number and localization of CD4(+) cells expressing the regulatory T-cell-specific transcription factor FOXP3 in the antrum and duodenum of duodenal ulcer patients, asymptomatic carriers, and uninfected individuals. We also determined gene expression levels of FOXP3 as well as anti- and proinflammatory cytokines before and after H. pylori eradication.

METHODS

Cellular FOXP3 expression was studied by immunofluorescence and flow cytometry, and transcription levels of FOXP3, interleukin (IL)-10, transforming growth factor-beta, CD4, and interferon-gamma were analyzed by real-time reverse transcription-polymerase chain reaction.

RESULTS

We found an increased (6-fold) frequency of CD4(+)FOXP3(+) T cells in H. pylori-infected gastric mucosa; interestingly 26% of these cells did not co-express CD25. The increase of FOXP3-expressing T cells in the antrum of infected individuals was dependent on the presence of H. pylori, since eradication therapy resulted in 4-fold lower levels of FOXP3 and IL-10 mRNA in the antrum. Furthermore, higher numbers of CD4(+)FOXP3(+) T cells were found in areas of duodenal gastric metaplasia in the duodenum of duodenal ulcer patients compared to duodenal gastric metaplasia of asymptomatic individuals and healthy mucosa in both patient groups. In duodenal ulcer patients, the CD4(+)FOXP3(+) T cells were more highly associated to aggregates in the duodenal mucosa.

CONCLUSION

The numbers of CD4(+)FOXP3(+) T cells are increased and localized in CD4(+) T-cell aggregates in areas of duodenal gastric metaplasia in duodenal ulcer patients.

Progress in vaccine development against Helicobacter pylori

Based on the very high prevalence of diseases caused by Helicobacter pylori, particularly in the developing world, and the rapid emergence of antibiotic resistance among clinical isolates, there is a strong rationale for an effective vaccine against H. pylori. In this review we describe recent promising candidate vaccines and prophylactic or therapeutic immunization strategies for use against H. pylori, as well as studies to identify immune responses that are related to protection in experimental animals. We also describe identification of different types of immune responses that may be related to protection against symptoms based on comparisons of H. pylori-infected patients with duodenal ulcers or gastric cancer and asymptomatic carriers. We conclude that there is still a strong need to clarify the main protective immune mechanisms against H. pylori as well as to identify a cocktail of strong protective antigens, or recombinant bacterial strains that express such antigens, that could be administered by a regimen that gives rise to effective immune responses in humans.

Analysis of common transforming growth factor beta-1 gene polymorphisms in gastric and duodenal ulcer disease: pilot study

BACKGROUND AND AIM

Transforming growth factor-beta1 (TGF-beta1) has been shown to be an important cytokine that plays a role in cell proliferation, differentiation, tissue injury repair and ulcer healing. The purpose of this pilot study was to investigate if common polymorphisms Leu10Pro, Arg25Pro and C-509T within the TGF-beta1 gene are associated with susceptibility to gastric and duodenal ulcer disease in Russians.

METHOD

Blood samples from 377 unrelated patients with gastric and duodenal ulcer disease and 226 sex- and age-matched healthy controls were used to determine TGF-beta1 gene polymorphisms by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS

Leu10Pro substitution in the signal peptide of TGF-beta1 has been found to be associated with susceptibility to gastric ulcer (odds ratio [OR] 1.76, 95% confidence interval [CI] 1.12-2.77). A genotype combination of 10Leu/Leu x 25Arg/Arg x -509C/C was also associated with susceptibility to gastric ulcer disease (OR 1.81, P = 0.01). In addition, the frequency of a combination of genotypes 10Pro/Pro x 25Arg/Pro x -509C/T was statistically lower in patients with duodenal ulcer than in controls (OR 0.42, P = 0.05). A significant difference (P = 0.04) in the distribution of rare haplotypes of the TGF-beta1 gene between patients with duodenal ulcer and healthy controls has been found. Polymorphism Leu10Pro was in positive linkage disequilibrium with C-509T polymorphism (coefficient D = 0.191; P < 0.0001).

CONCLUSIONS

These findings indicate that the Leu10Pro and C-509T polymorphisms may be involved in the modulation of expression of the TGF-beta1 gene, and therefore a predisposition to peptic ulcer disease could be linked to particular alleles of this gene. In particular, a possible role of TGF-beta1 in the pathogenesis of gastric ulcer disease is discussed.

Differential regulation of gastric tumor growth by cytokines that signal exclusively through the coreceptor gp130

BACKGROUND & AIMS

We have shown that mice with a mutation in gp130 (gp130(757F/F)), the signal transducing receptor for interleukin (IL)-6 family cytokines, have chronic gastric inflammation and develop distal stomach tumors associated with deregulated phosphorylated STAT3 expression. This model recapitulates many characteristics of intestinal-type gastric cancer in humans.

METHODS

To evaluate the role of IL-6 and IL-11 as ligands regulating tumor growth and submucosal invasion, we compared tumor characteristics of gp130(757F/F) mice with gp130(757F/F) mice lacking IL-6 or mature T and B cells.

RESULTS

As a result of the gp130(757F/F) mutation, expression of IL-6 and IL-11 was greatly up-regulated concomitant with activation of STAT3 and development of tumors. However, the lack of IL-6 or T and B cells did not impact on tumor growth. While IL-6 did not regulate tumor growth or tumor vascularization, gp130(757F/F)/IL-6(-/-) mice showed approximately 10-20-fold more submucosal tumor invasion, reduced mononuclear inflammatory cell infiltrate, and greater IL-11 and matrix metalloproteinase (MMP)-13 and MMP-9 synthesis than gp130(757F/F) mice. Expression of MMP-13 was largely restricted to tumor-associated stroma, but MMP-9 was also expressed in polymorphonuclear cells and a subset of epithelial cells. In addition, treatment with recombinant IL-11 stimulated expression of MMP-13 and MMP-9 in stomachs of wild-type mice.

CONCLUSIONS

Increased submucosal invasion in gp130(757F/F)/IL-6(-/-) mice could not be explained by increased vascularization or reduced immunosurveillance but was most likely facilitated by augmented metalloproteinase activity driven by elevated IL-11 levels.

Down-regulation of epithelial IL-8 responses in Helicobacter pylori-infected duodenal ulcer patients depends on host factors, rather than bacterial factors

Helicobacter pylori infection is one of the most common gastrointestinal infections worldwide. Although the majority of the infected individuals remain asymptomatic carriers of the bacteria, approximately 15% develop peptic ulcers, which are most prevalent in the duodenum. H. pylori induce a vigorous immune response which, however, fails to clear the infection. Instead, the chronic inflammation that arises in the infected gastroduodenal mucosa may be involved in the development of H. pylori-associated peptic ulcers. We have previously shown that duodenal ulcer (DU) patients have a significantly lower epithelial cytokine, e.g. IL-8, response in the duodenum than asymptomatic (AS) carriers. In this study we have further investigated the mechanisms behind this finding, i.e. whether it can be explained by bacterial factors, down-regulation of epithelial cytokine production by regulatory T cells, or an impaired ability of the duodenal epithelium in DU patients to produce cytokines. Gastric AGS, and intestinal T84 epithelial cell lines were stimulated with H. pylori strains isolated from DU patients and AS carriers, respectively. All strains were found to induce comparable cytokine and cytokine receptor expression in epithelial cells. Regulatory T cells (CD4+ CD25(high)), isolated from human peripheral blood and cocultured with H. pylori stimulated AGS cells, were found to slightly suppress H. pylori-induced epithelial cytokine production. Furthermore, primary cultures of duodenal epithelial cells from DU patients were found to produce markedly lower amounts of cytokines than epithelial cells isolated from AS carriers. These results suggest that the lower epithelial cytokine responses in the duodenum of DU patients, which may be of importance for the pathogenesis of H. pylori-induced duodenal ulcers, most likely can be explained by host factors, i.e. mainly a decreased ability of the duodenal epithelium to produce cytokines, but possibly partly also down-regulation by regulatory T cells.

CD4+CD25+suppressor T cells regulate pathogen induced inflammation and disease

A key suppressor role has recently been ascribed to the natural CD4+CD25+ regulatory T cells (Treg), the removal of which leads to the development of autoimmune disease and aggravated pathogen-induced inflammation in otherwise normal hosts. The repertoire of antigen specificities of Treg is as broad as that of naive T cells, recognizing both self and non-self antigens, enabling Treg to control a broad range of immune responses. Although widely acknowledged to play a role in the maintenance of self-tolerance, recent studies indicate that Treg can be activated and expanded against bacterial, viral and parasite antigens in vivo. Such pathogen-specific Treg can prevent infection-induced immunopathology but may also increase the load of infection and prolong pathogen persistence by suppressing protective immune responses. This review discusses the role of Treg in the prevention of exaggerated inflammation favoring chronicity in bacterial or fungal infections and latency in viral infections. Special attention is given to the role of Treg in the modulation of gastric inflammation induced by Helicobacter pylori infection. Findings in both experimentally infected mice and humans with natural infection indicate that Treg are important in protecting the H. pylori-infected host against excessive gastric inflammation and disease symptoms but on the negative side promote bacterial colonization at the gastric and duodenal mucosa which may increase the risk in H. pylori-infected individuals to develop duodenal ulcers.

Mucosal FOXP3-expressing CD4+ CD25high regulatory T cells in Helicobacter pylori-infected patients

Helicobacter pylori chronically colonizes the stomach and duodenum and causes peptic ulcers or gastric adenocarcinoma in 10 to 20% of infected individuals. We hypothesize that the inability of patients to clear H. pylori infections is a consequence of active suppression of the immune response. Here we show that H. pylori-infected individuals have increased frequencies of CD4(+) CD25(high) T cells in both the stomach and duodenal mucosa compared to uninfected controls. These cells have the phenotype of regulatory T cells, as they express FOXP3, a key gene for the development and function of regulatory T cells, as well as high levels of the cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) protein. In contrast, mucosal CD4(+) CD25(low) and CD4(+) CD25(-) cells express little FOXP3 mRNA and low levels of the CTLA-4 protein. Mucosal CD4(+) CD25(high) T cells are present in individuals with asymptomatic H. pylori infections as well as in duodenal ulcer patients. The frequencies of CD4(+) CD25(high) cells are also increased in the stomachs of H. pylori-infected patients with gastric adenocarcinoma, particularly in cancer-affected tissues. These findings suggest that regulatory T cells may suppress mucosal immune responses and thereby contribute to the persistence of H. pylori infections.

Do procalcitonin and C-reactive protein levels have a place in the diagnosis and follow-up of Helicobacter pylori infections?

The aims of this study were to determine the levels of procalcitonin (PCT) and C-reactive protein (CRP) in Helicobacter pylori-positive (HP+) patients diagnosed with duodenal and gastric ulcer and to evaluate the correlation of PCT and CRP levels with other invasive and non-invasive diagnostic methods for determination of H. pylori eradication in post-treatment follow-up. Thirty-five HP+ patients with dyspepsia were included in this study. Serum samples (5 ml) were collected at admission and after 24 h. Antimicrobial therapy (omeprazole, amoxycillin and clarithromycin) was given for 1 week to HP+ patients who were positive only by culture or by urease test plus pathology. After 1 month, serum samples (5 ml) were collected again and culture, urease and pathology investigations were performed on endoscopic samples. PCT and CRP levels were measured in the collected blood samples. Thirty-five H. pylori-negative (HP-) cases with dyspepsia, 38 cases with bacteraemia and 35 healthy blood donors were included in this study as control groups. The mean and minimum-maximum levels of PCT were 1.39 (0.25-6.75), 0.35 (0.12-0.71), 7.45 (0.68-51.5) and 0.40 (0.12-0.71) ng ml(-1) for the groups of HP+, HP- and bacteraemia patients and healthy donors, respectively. Mean CRP levels were 1.00 (<0.5-8.11), 0.62 (<0.5-3.2), 11.5 (3.2-43.5) and 0.63 (<0.5-5.46) mg dl(-1) for the same groups. A statistically significant difference was found between HP+ patients and both HP- cases and healthy blood donors for PCT levels, and higher PCT levels were found on admission in cases of bacteraemia than in the other groups (P < 0.05). PCT levels of HP+ cases decreased significantly (from 1.39 to 0.86) between admission and the post-treatment period (30 days); however, PCT levels remained higher than the cut-off value (0.5 ng ml(-1)). Similar ranges of CRP levels were found over the same time-period. The sensitivity of PCT was found to be higher than that of CRP on admission, but the specificity of PCT was found to be lower than that of CRP on the day of admission (65 and 74%, respectively). The sensitivity of PCT was the same as that of CRP for the post-treatment period, but specificity of PCT was higher than that of CRP for the post-treatment period (83 and 76%, respectively). It was concluded that PCT and CRP are not very effective markers for H. pylori infection in primary diagnosis or in eradication follow-up after therapy when used in parallel with conventional diagnostic methods, even if there is a difference in PCT and CRP levels between HP+ and HP- cases on admission.