Synthesis, Structure and Antimicrobial Properties of Novel Benzalkonium Chloride Analogues with Pyridine Rings.

Quaternary ammonium compounds (QACs) are a group of compounds of great economic significance. They are widely used as emulsifiers, detergents, solubilizers and corrosion inhibitors in household and industrial products. Due to their excellent antimicrobial activity QACs have also gained a special meaning as antimicrobials in hospitals, agriculture and the food industry. The main representatives of the microbiocidal QACs are the benzalkonium chlorides (BACs), which exhibit biocidal activity against most bacteria, fungi, algae and some viruses. However, the misuses of QACs, mainly at sublethal concentrations, can lead to an increasing resistance of microorganisms. One of the ways to avoid this serious problem is the introduction and use of new biocides with modified structures instead of the biocides applied so far. Therefore new BAC analogues P13-P18 with pyridine rings were synthesized. The new compounds were characterized by NMR, FT-IR and ESI-MS methods. PM3 semiempirical calculations of molecular structures and the heats of formation of compounds P13-P18 were also performed. Critical micellization concentrations (CMCs) were determined to characterize the aggregation behavior of the new BAC analogues. The antimicrobial properties of novel QACs were examined by determining their minimal inhibitory concentration (MIC) values against the fungi Aspergillus niger, Candida albicans, Penicillium chrysogenum and bacteria Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa. The MIC values of N,N-dimethyl-N-(4-methylpyridyl)-N-alkylammonium chlorides for fungi range from 0.1 to 12 mM and for bacteria, they range from 0.02 to 6 mM.

[Intensification of Helicobacter pylori colonization and serological markers of Helicobacter pylori infection and cytotoxicity in blood]. / Nasilenie kolonizacji bakterii Helicobacter pylori, a serologiczne markery zakazenia i cytotoksycznosci Helicobacter pylori we krwi.

UNLABELLED: Colonization of H. pylori bacteria on the surface of gastric epithelium is the first stage of infection in alimentary tract. Despite the local cell-mediated reaction, in the majority of patients there does not come to the elimination of bacteria: there develops an acute and then chronic inflammatory process. B lymphocytes begin the production of all classes of specific antibodies against H. pylori proteins presented to them. The number of anti-H. pylori antibodies increases both in gastric mucosa and in peripheral blood. According to some researchers the intensification of colonization influences the severity of inflammatory process. AIM OF THE STUDY: To assess whether on the basis of examination of anti-H. pylori and anti-CagA H. pylori surface antibodies in blood it may be concluded that there is an intensification of H. pylori colonization in the stomach. MATERIAL AND METHODS: The study comprised 154 children aged 5-18 years (mean 13.6 +/- 3.6 years) with alimentary tract ailments: 99 children with active H. pylori infection (Hp+) and 55 children without current H. pylori infection (Hp_). In blood there were examined anti-H. pylori surface antigens IgG class (with ELISA), anti-CagA H. pylori antibodies IgG class (with ELISA), and in gastric mucosa specimens the intensification of H. pylori colonization was tested with the use of semi quantitative method. Statistic analyses were performed. RESULTS: Anti-H. pylori antibodies IgG class were present in the serum of 88.3% of the examined children, including in 96% of children from Hp+ group and 75% from Hp_ group. Anti-CagA H. pylori specific antibodies were found in 56.7% of children from Hp+ group and were not detected in Hp_ children. Spiral H. pylori forms were more frequently revealed in the prepyloric part of the stomach (of medium or small intensification) than in the corpus (of small intensification) (77.8% vs. 56.5%, p < 0.001). Positive correlation was demonstrated between the number of bacteria in tissue and index value of antibodies against anti-H. pylori surface antigens in serum (R = 0.45, p < 0.001) (particularly in the prepyloric part of the stomach) and high positive correlation was shown between density of spiral H. pylori bacteria in gastric mucosa bioptates and the occurrence of anti-CagA antibodies in serum (R = 0.59, p < 0.001) and index value of anti-CagA H. pylori antibodies in serum (R = 0.58, p < 0.001). CONCLUSIONS: High concentrations of anti- H. pylori IgG class surface antibodies and occurrence of anti-CagA antibodies in blood correlate with high intensification of H. pylori colonization in the prepyloric part of the stomach.

Anti-phagocytic activity of Helicobacter pylori lipopolysaccharide (LPS)--possible modulation of the innate immune response to these bacteria.

The Helicobacter pylori infections are followed by an infiltration of the gastric mucosa by neutrophils and macrophages. Accumulation of phagocytes enables them to interact with H. pylori, but a great number of infected subjects cannot eradicate these bacteria. The H. pylori inhibits its own uptake by blocking the function of phagocytes. The anti-phagocytic mechanism depends on bacterial surface structures and the presence of the cag pathogenicity island (PAI). The role of H. pylori lipopolysaccharide (LPS), during phagocytosis of these bacteria is not clear. LPS may mediate direct bacteria/phagocyte interactions and it may also regulate antibacterial activity of the phagocytes. In this study we investigated the influence of H. pylori LPS on phagocytosis of these bacteria. The H. pylori LPS inhibited an ingestion of these microbes by human peripheral blood granulocytes. This was correlated with a diminished ability of phagocytes to reduce MTT-tetrazolium salt. The anti-phagocytic effect of H. pylori LPS was reduced by recombinant lipopolysaccharide binding protein (rLBP). It is possible that in vivo H. pylori LPS may diminish elimination of these bacteria from the gastric mucosa promoting an infection persistence. However, LBP may modulate the uptake of H. pylori due to neutralization of anti-phagocytic effect of its LPS.

[Comparable evaluation of usefulness of traditional methods and polymerase chain reaction technique in detection of Helicobacter pylori infection]. / Porównawcza ocena przydatnosci tradycyjnych metod i techniki lancuchowej reakcji polimerazy w wykrywaniu zakaienia Helicobacter pylori.

UNLABELLED: H. pylori is a well recognized pathogenic factor of chronic gastritis and class I carcinogen. Specimens are collected on gastroscopy performed due to clinical symptoms suggesting upper alimentary tract organic disease for pathomorphological examinations and for the estimation of the presence of H. pylori infection in urease test, histological examination in Giemsa staining method or in a culture. The aim of the project was to compare the detection of H. pylori in gastric mucosa in children by conventional method and polymerase chain reaction technique (PCR). MATERIAL AND METHODS: The study comprised 137 children and adolescents, aged 5-18 years (mean 13.2 years), in whom basing on the evaluation of the level of serum anti-H.pylori antibodies (ELISA), urease test and histological examination (HE), H. pylori infection was diagnosed or excluded. H. pylori genes: ureA, vacA, cagA were identified in gastric mucosa specimens with PCR method. RESULTS: On the grounds of standard methods H. pylori was detected in 86 (62.8%) and excluded in 51 (37.2%) children. UreA gene was detected in gastric mucosa in 82 (95.3%) children with H. pylori (Hp+) and in 8 (15.7%) without H. pylori (Hp-) infection (p < 0.001). CagA H. pylori gene was identified in 21 (24.4%) children from Hp+ group and in 1 (2%) from Hp- group (p < 0.001), and vacA gene in 23 (26.7%) and 6 (11.8%) (NS), respectively. H. pylori strains type I (cagA+/vacA+) were found in gastric mucosa of 15 (17.4%) Hp+ patients. CONCLUSIONS. Testing of H. pylori genes (particularly ureA gene) with PCR technique in mucosa bioptates enables to diagnose H. pylori infection even in patients with the infection not detected with standard methods.

Potential role of LPS in the outcome of Helicobacter pylori related diseases.

In this study we asked a question whether H. pylori LPS with or without LewisXY (Le) determinants as well as LBP (lipopolysaccharide binding protein) and sCD 14 molecules recognizing bacterial LPS may be involved in atherogenesis. Sera from 57 patients with coronary heart disease (CHD), 27 H. pylori infected dyspeptic patients-H.p.(+) and 49 healthy controls (HC) were tested for IgM and IgG to H. pylori LPS expressing LeX (LPS LeX) or LeXY (LPS LeXY) determinants and to a glycine acid extract (GE). Immune complexes (ICs) of Lewis antigens and specific IgM or IgG were also determined. The prevalence of anti-GE IgG and IgA was significantly higher in CHD as compared to HC and the same as in the H.p.(+) group. The highest levels of anti-GE IgG were detected only for CHD group. CHD patients showed upregulation of IgG to LPS LeX and LeXY. In contrast, an upregulation of IgM to such LPSs was found for healthy subjects. The levels ofLeY-anti-LeY IgG ICs were higher in CHD patients than in healthy controls similarly to the levels of LBP. There was no difference in sCD14 concentration between CHD and HC groups. The results obtained in this study indicate that H. pylori infections may be the risk factors of atherosclerosis due to: 1) an enhanced humoral response to H. pylori surface antigens, 2) a host predisposition to respond to Lewis determinants present in H. pylori LPS by IgG, 3) increased levels of serum LBP.

[Detrusor pseudohyperactivity syndrome in children with constipation]. / Zespól rzekomej nadreaktywnosci wypieracza u dzieci z zapaciami.

THE AIM OF THE STUDY: was the evaluation of dependencies occurring between constipation and observed nocturia, pressing tenesmus and daytime urinary incontinence. MATERIAL AND METHODS: the studies were conducted in 51 children aged between 3 and 17 years including 25 girls and 26 boys hospitalized in the Clinical Department because of nocturia, pressing tenesmus and daytime urinary incontinence. In all children a complex diagnostic work up of the urinary system and the lower segment of alimentary tract was performed. Results of the examinations were compared to the control group. RESULTS: analysis of the results of the conducted examinations indicates that the overblown rectal ampulla, through the pressure exerted on the urinary bladder, seemingly decreases its volume causing the occurrence of pressing tenesmus, nocturia and daytime urinary incontinence. This process leads to the formation of detrusor hyperactivity syndrome characterized by: chronic constipation, increase of miction frequency and simultaneous decrease of volume of each portion of urine, nocturia and/or daytime urinary incontinence. CONCLUSIONS: chronic constipation disturbs the functional-morphological equilibrium between the end segment of alimentary tract and the urinary bladder. By influencing the process of filling and accumulation of urine in the bladder they lead to the formation of detrusor hyperactivity syndrome.

Natural mannose-binding lectin (MBL) down-regulates phagocytosis of Helicobacter pylori.

Considering the role of lectin-carbohydrate interactions between Helicobacter pylori bacteria and the host cells we addressed the question on how mannose binding lectin - MBL, present in human plasma, may influence the phagocytosis of H. pylori by peripheral blood granulocytes. For phagocytosis assay the granulocytes separated from peripheral blood of healthy H. pylori-seronegative donors were used. Phagocytosis was estimated by fluorescence assay using FITC-labelled H. pylori cells. The MBL level in the serum samples as well as MBL-binding to H. pylori bacteria were estimated by ELISA. In this study all H. pylori isolates bound recombinant mannose binding lectin-MBL as shown by ELISA. The ingestion of H. pylori bacteria in the medium with human serum depleted in natural MBL (nMBL) was more intensive than in the medium with complete serum containing nMBL. Moreover, the ingestion of H. pylori bacteria in the medium with complete serum was increased by an addition of anti-rMBL IgG. The results indicate that interaction of bacterial and host lectins may regulate the phagocytosis of H. pylori bacteria and in this way influence an outcome of the infection caused by these microbes.

[Assessment of postvaccinal response in children past pertussis]. / Ocena odpowiedzi poszczepiennej u dzieci, które przebyly krztusiec.

In the nineties, despite high percentage of vaccination of children, from 86% to 99% dependently on the region, there came to the increase of whooping cough cases. Until then infants and children to the age of 5 years suffered from this disease, whereas in the last decade the number of cases increased mainly among children over 5 years of age, who were subjected to full cycle of vaccination against whooping cough. Searching for the causes of such epidemiologic situation the following suggestions have been given: change of the bacteria antigenicity, the phenomenon of postvaccinal immunity extinction, immune system mechanisms disorders and groundless excuse from vaccination. The study estimates parameters of postvaccinal response to immunization with selected vaccines in children post whooping cough.

[Neutrophils and selected cytokines in ulcerative colitis pathomechanism]. / Udzial neutrofilów i wybranych cytokin w patomechanizmie wrzodziejacego zapalenia jelita grubego.

The aim of the study was to assess receptor CD11b and CD62L expression on neutrophils and IL-1beta, IL-6 and IL-8 level in children with ulcerative colitis. Thirty children aged 8-17 years were included in the study. The investigations were performed in the acute phase, prior to the treatment and during remission, 2 months after clinical improvement was obtained. The control group consisted of 12 children with chronic obstipation. IL-1beta, IL-6 and IL-8 serum level and receptor CD11b expression, especially on resting neutrophils, in children with severe and moderate course of the disease were statistically significantly higher; whereas CD62L expression was significantly lower in comparison with the controls and got back to normal during remission. Increased IL-1beta level was observed only in children with severe disease course. In children with mild process the results of the investigations were similar to the control group. In children with severe disease activity the proinflammatory cytokines levels in serum were elevated. The neutrophils in children with severe course of the disease manifested priming in peripheral blood before leaving the circulation.

[Mucus physicochemical properties in children with ulcerative colitis]. / Wlasciwosci fizykochemiczne sluzu u dzieci z wrzodziejacym zapaleniem jelita grubego.

The aim of the study was to estimate colonic mucus physicochemical state in children with ulcerative colitis. Investigations were performed in 36 children, aged 10-17 years, allotted into three groups dependently on the severity of the disease. The severity of the disease was estimated basing on Truelove-Witts criteria. Mucus analysis was performed with polyacrylamide gel electrophoresis (SDS-PAGE), electron paramagnetic resonance (EPR) and spectrophotometric method. Mucus fraction dissolved in normal saline was subject of investigations. Protein content was determined in this fraction with Lowry's method. The obtained results demonstrated different mucus solubility dependent on the severity of the disease. Mucus protein concentration increased whereas mucus viscosity decreased with the severity of the disease. Colonic mucus physicochemical properties change dependently on the disease severity. Determination of soluble protein fraction in mucus may be a useful marker in the estimation of the disease severity.

[Irritable bowel syndrome--pathogenesis, management]. / Zespól jelita drazliwego--patogeneza, postepowanie.

Irritable bowel syndrome creates many diagnostic and treatment difficulties in a general practitioner practice as well as in a specialist practice. Etiopathogenesis of this illness still elicit some controversy. In a diagnostic process, apart from an organic basis excluding, the most important is a medical history of a patient because of the fact that a right symptoms interpretation usually allows a correct diagnosis establishment. A treatment is in its premise a symptomatic treatment, is long-lasting and based on a mutual trust between a doctor and a patient. Basic information concerning this illness is presented in this article.

[Peptic ulcer disease etiology, diagnosis and treatment]. / Choroba wrzodowa--etiopatogeneza, rozpoznawanie i leczenie.

Authors in this article present etiology, clinical manifestations, diagnostic procedures and treatment of peptic ulcer disease in children and adults. Increased gastric acid output, Helicobacter pylori, NSAIDs and stress are the basic risk factors in peptic ulcer disease. H. pylori infection is a widely known risk factor in peptic ulcer disease and influences diagnostic and treatment procedures. Primary ulcer disease concerns mainly duodenum and is accompanied by H. pylori infection. Gastroscopy and Helicobacter tests are the only reliable procedures to diagnose peptic ulcer disease. Nowadays the most important aim in peptic ulcer treatment is the H. pylori eradication. Therapy with two antibiotics and a protein pomp inhibitor eradicates the bacteria, treats the ulceration and lowers the number of ulcer recurrence. In non-infected H. pylori ulcers or in a long-term treatment protein pomp inhibitors and H2-inhibitors are effective as well in gastroprotective therapy.

[The role of Candida sp. in etiopathogenesis of esophageal, gastric and duodenal mucosa inflammation in children]. / Rola grzybów z rodzaju Candida w etiopatogenezie przewleklego zapalenia blony sluzowej przelyku, zoladka i dwunastnicy u dzieci.

UNLABELLED: The aim of the study was to demonstrate morphological traits of Candida-induced upper alimentary tract mucosa inflammation. The material for the study comprised 18 children aged 4 to 18 years treated at the I Department of Paediatrics and Gastroenterology, Institute Polish Mother Health Centre. In these children positive mycologic cultures were obtained from alimentary tract inflammed mucosa sections. Upper alimentary tract endoscopy was performed and macroscopic and microscopic evaluation was made. Children with excluded H. pylori infection, reflux disease, lambliosis and allergy were included into the investigated group. Savara-Muller's classification was used for oesophageal mucosa inflammation evaluation, whereas gastric and duodenal mucosa inflammation were assessed according to Tytgat. RESULTS: the most frequent macro lesions concerned simultaneously gastric and duodenal mucosa (44.46%). 27.77% of patients demonstrated oesophagitis, gastritis and duodenitis. In histopathological examination inflammatory lesions in oesophageal mucosa were observed in 38.88% (most frequently I degree). Chronic gastritis was found in all children, non-active in 11 and active in 7. Duodenal mucosa demonstrated traits of chronic active inflammation in 8 children and chronic in 5 of them. CONCLUSIONS: Candida fungi may be an etiopathogenetic factor of oesophageal, gastric and duodenal mucosa inflammation, Candida-induced mucosa inflammation is most frequently of chronic nature.

[Clinical course of toxocarosis in children]. / Przebieg kliniczny toksokarozy u dzieci.

The aim of the study was to monitor the clinical course of T. canis infection in children with particular consideration of the estimation of infected children's immune system. The study comprised 52 children, aged 3 to 18 years, diagnosed and treated at the I Department of Paediatrics and Gastroenterology, Institute Polish Mother Health Centre, in whom infection with Toxocara canis larva was confirmed with serologic test. The control group included 38 children, aged 3 to 16 years in whom no infection with this parasite was detected in serologic test. In the investigated children subjective and physical examinations were performed, clinical symptoms, changes in organs, haematological, biochemical investigations and selected parameters of humoral and cellular immunity were analysed. In children with toxocarosis most frequently not localized abdominal pain, subfebrile body temperature and generalized lymphadenitis were observed. Significantly higher percentage of eosinophil cells and immunoglobulin E serum concentration with decreased percentage of lymphocytes CD3+, CD4+ and CD4/CD8 ratio were found in the investigated children. Toxocarosis diagnosis is difficult because its clinical symptoms are differentiated and not characteristic, what requires broadening of differential diagnosis concerning numerous entities.

[Assessment of the response of peripheral blood mononuclear leukocytes on Helicobacter pylori infection in children]. / Ocena odpowiedzi swoistej limfocytów z krwi obwodowej na zakazenie Helicobacter pylori u dzieci.

In the study the proliferative response of peripheral blood mononuclear leukocytes (PBML) from children with chronic dyspepsia (chr. d) to H.p. antigens was investigated. From 38 children aged 7-18, with chr. d., blood was collected just before upper GI endoscopy. Twenty one patients were found to be H.p. (+). PBML were used for the cultures and were stimulated with heat-killed H.p. G27 bacteria, heated and unheated glycine extract (GE) of H.p. G27 or with H.p. LPS containing Lewis X and Lewis Y determinants, in the presence or absence IL-2. The cell proliferation was estimated on the basis of [3H] - thymidine incorporation. In the cultures, the phenotype of responding cells was determined by an EIA with monoclonal antibody to human CD3, CD4 and CD8. PBML from patients H.p. (-), responded to killed H.p. bacteria and to heated GE more frequently and more intensively than PBML from the H.p.(+). IL-2 enhanced PBML response to these antigens. Unheated GE did not induce PBML proliferation even in the cultures with IL-2. LPS alone induced proliferation of PBML from 3 patients (2 H.p. - and 1 H.p.+). However, in the presence of IL-2, LPS induced proliferation of PBML from 15 patients. In the cultures of PBML stimulated with whole bacteria or heated EG, T cells dominated. In the cultures of PBML from H.p. (+) we found a higher percentage of CD8 cells in comparison with the cultures of PBML from H.p. (-). Data demonstrate a significant variation in the response of PBML from dyspeptic children to H.p. antigens.

[Drug sensitivity of Helicobacter pylori strains in children and young people from the region of Lódz]. / Lekowrazliwosc szczepów Helicobacter pylori u dzieci i mlodziezy regionu lódzkiego.

Combined therapy with a proton pump inhibitor and two antibiotics (metronidazole, clarithromycin and amoxicillin or tetracycline) is applied in the treatment of H. pylori infection. The effects of the treatment depend on drug sensitivity of H. pylori. Growing resistance to some of the applied antibiotics has been observed. The aim of the study was to assess drug sensitivity of Helicobacter pylori strains which were isolated from the gastric mucosa of children and young people living in the macroregion of Lódz. The study comprised 45 children aged between 5 and 18 years. Biopsy specimens were put on transport medium, incubated in microaerophilic environment, then identified. Drug sensitivity to metronidazole, clarithromycin, amoxicillin and tetracycline was assessed. We found resistance to metronidazole in 18% (8/45) children, resistance to clarithromycin in 16% (7/45) children and resistance to both antibiotics in 4% (2/45) children. No resistance to amoxicillin or tetracycline was noted.

Serological differentiation of Helicobacter pylori CagA(+) and CagA(-) infections.

Many Helicobacterpylori strains causing gastroduodenal diseases have a cagA gene encoding CagA protein, a virulence factor of these bacteria. Anti-CagA antibodies produced by the majority of people infected with CagA(+) strains can indicate such an infection. In this study, the efficacy of three immunoenzymatic tests for detecting CagA(+) and CagA(-) infections were compared: immunoblot (Milenia ID Blot H. pylori IgG; MB) and ELISA conducted either with a recombinant immunodominant fragment of CagA (rCagA) or the full-length CagA molecule (flCagA). The 13C-urea breath test (13C-UBT) was used for establishing H. pylori status. The serum samples from 157 individuals were used for serodiagnosis. H. pylori CagA(+) infection was detected in H. pylori-infected individuals with similar frequencies by MB (64%) and flCagA-ELISA (60%) and a little less frequently by rCagA-ELISA (53%). There was a high coincidence between the negative results of these three tests for H. pylori-uninfected individuals with no anti-CagA IgG in the serum (96-100%). The results show that rCagA-ELISA and, especially, flCagA-ELISA are easy, inexpensive and useful noninvasive assays for the discrimination of CagA(+) and CagA(-) H. pylori infections in subjects examined by urea breath test.

Helicobacter pylori lipopolysaccharide in the IL-2 milieu activates lymphocytes from dyspeptic children.

In this study, we assessed the proliferative response of peripheral blood mononuclear leukocytes (PBML) from 33 children/young adolescents with chronic dyspepsia, to H. pylori LPS in the presence and absence of IL-2 as a T cell growth factor. A rapid urease test (RUT) and a presence of Helicobacter-like organisms (HLO) in the biopsy specimens allowed us to distinguish RUT/HLO-positive (17/33) and -negative (16/33) patients. H. pylori LPS alone induced a proliferation of PBML from 4 out of 33 dyspeptic patients. IL-2 increased the prevalence of the response to LPS to 59% and 74% of RUT/HLO-positive and -negative patients, respectively. PBML from RUT/HLO-positive patients responded significantly less intensively to H. pylori LPS in the presence of IL-2, to IL-2 alone and to H. pylori LPS+IL-2. However, there was no difference in PHA-driven proliferation of PBML from the patients of those two groups. A negative correlation between the responsiveness to H. pylori LPS of PBML and occurrence of type B inflammation in gastric mucosa was demonstrated. The results suggest a contribution of H. pylori LPS to an outcome of H. pylori infection. It is speculated that H. pylori LPS by an activation of immunocompetent cells may reduce gastric inflammation, decrease bacterial load and prolong H. pylori infection.

Detection of specific Helicobacter pylori DNA and antigens in stool samples in dyspeptic patients and healthy subjects.

In this study stool samples from dyspeptic patients and healthy subjects were used for detection of specific Helicobacter pylori antigens and DNA by immunoenzymatic test (PPHpSA) and semi-nested PCR (ureA-PCR), respectively. The H. pylori status was estimated by invasive endoscopy-based rapid urease test and histology or noninvasive urea breath test (UBT), and by serology (ELISA, Western blot). The coincidence of H. pylori-negative invasive tests or UBT and negative antigen or DNA stool tests was very high (mean 95%). The PPHpSA results were found positive for 56% and ureA-PCR for 26% of individuals with H. pylori infection confirmed by invasive tests or UBT. The detection of specific H. pylori antigens and especially DNA in feces is not sufficient as a one-step diagnosis of H. pylori infection.

[Intrahepatic and peripheral blood NK cells in patients with chronic hepatitis C]. / Analiza wspólzaleznosci pomiedzy komórkami nk watroby i krwi obwodowej u dzieci z przewleklym zapaleniem watroby typu c.

UNLABELLED: The aim of this study was to evaluate the correlation between NK (natural killers) cells in an inflammatory infiltration of the liver and in peripheral blood in children with chronic hepatitis type C. MATERIAL AND METHODS: The study comprised 25 children with chronic hepatitis type C. The control group comprised 10 children with no liver disease in past medical history and normal activity of aminotransferases. In the study group, liver biopsy specimens were evaluated by histopathology and immunomorphology - the presence of NK cells present in the inflammatory infiltrate was determined. In all children the percentage and absolute count of NK cells in peripheral blood was evaluated by flow cytometry, as well as the activity of NK cells in relation to leukaemic cells of erythroleukemia K-562 without stimulation and after the stimulation with IL-2 (in vitro). RESULTS: In the studied group of children NK cells constituted 6.07 +/- 3.92 % of cells present in liver infiltrate. In peripheral blood NK cells constituted 11.68 +/- 6.73 % of white blood cells, and their absolute number was 241.08 +/- 128.56 /ml. The cytotoxic activity of NK cells in dilution E:T 25:1 was - 91.8 +/- 1.07 % and in dilution E:T 12.5:1 - 6.72 +/- 3.68 %. After stimulation with IL-2 it was 92.8 +/-1.01 % and 7.58 +/- 3.95 %, respectively. The number of NK cells in peripheral blood and cytotoxic activity of NK cells in the studied group did not differ from that of the control group. There was a positive correlation between the percentage of NK cells in the liver infiltrate and the absolute number of NK cells in the peripheral blood and between percentage of NK cells in the inflammatory infiltrate and cytotoxic activity of NK cells in peripheral blood, stimulated and non-stimulated with IL-2 in proportion E:T 12.5:1. CONCLUSIONS: Positive correlation between the number of NK cells in peripheral blood and liver infiltrate suggests the possibility of evaluating NK cells involvement in the pathogenesis of chronic hepatitis type C in children on the basis of peripheral blood tests.