Serological markers of pulmonary tuberculosis and of response to anti-tuberculosis treatment in a patient population in Guinea.

The aim of the study was to evaluate serological correlates of active tuberculosis and of response to antituberculosis treatment in a cohort of HIV-negative patients with pulmonary tuberculosis studied at diagnosis and during treatment at the Service de Pneumo-Phtisiologie, Centre Hospitalier-Universitaire Ignace Deen, Conakry, Republic of Guinea. Two similar cohorts of HIV-negative healthy households of patients and healthy community controls were included in the study. Plasma samples were obtained from 168 untreated tuberculosis patients, 167 healthy household controls, and 168 healthy community controls. Serial plasma samples were also obtained from the tuberculosis patients at 2 and 8 months after initiation of chemotherapy. IgG antibody levels were measured by an enzyme-linked immunosorbent assay (ELISA) using ten purified M. tuberculosis antigens. ELISA results were analysed by comparing geometric means of data. Of the ten antigens tested, five (14kDa Ag, 19kDa Ag, AlaDH, MS, and MPT83) elicited similar antibody responses in untreated TB patients and controls. In contrast, levels of three antibodies (ESAT-6, LAM, and 38kDa Ag) were higher in untreated TB patients than in household or community controls (p<0.0001). Levels were higher in untreated patients than in community controls also for the anti-Rv2626c antibody (p = 0.0001) and, at a lower significance level, for the anti-FdxA antibody (p<0.025). Antibody levels against ESAT-6 and Rv2626c decreased during therapy, while antibody levels to the 38 kDa antigen and LAM increased during therapy; FdxA antibody levels did not vary with treatment. Neither severity of presentation nor chest X-ray patterns affected levels of these antibodies before treatment. In contrast, after the 8-month therapeutic course, patients who presented with moderate/severe disease had higher levels of anti-ESAT-6, anti-FdxA, and anti-38kDa antibodies than those of patients with mild disease onset. Patients with bilateral lung lesions had significantly higher anti-38kDa and anti-LAM levels, both at diagnosis and after 8-month treatment, than patients with lesions involving only one lung. Antibodies to alanine dehydrogenase and malate synthetase measured at initiation of treatment were higher in tuberculosis patients who subsequently failed therapy than in those who were cured. The main conclusions of the study are: a) plasma levels of antibodies to a number of M. tuberculosis represent serological correlates of active disease; b) these correlates are affected in an antigen-specific fashion by anti-tuberculosis treatment; c) particular serological markers may be predictive of treatment outcome.

Preferential Th1 profile of T helper cell responses in X-linked (Bruton's) agammaglobulinemia.

X-linked agammaglobulinemia (XLA) is a primary immunodeficiency of the B-cell compartment caused by a defective gene encoding for the tyrosine kinase (btk) essential for B cell differentiation. Affected males undergo recurrent pyogenic infections and deficient immunoglobulin production. Peripheral blood T cells from 6 XLA patients and 6 matched healthy controls were stimulated with either PHA or tetanus toxoid (TT) and T cell clones obtained were compared for their cytokine profile. In the series of PHA-induced or TT-specific CD4(+) T cell clones derived from XLA patients, the Th1 profile was predominant (63 and 65 %, respectively). Upon stimulation with TT, the proportion of activated T cells from XLA that expressed the IFN-gamma -associated LAG-3 activation molecule was higher than in control T cells (51 vs. 25 %), whereas the expression of the IL-4-associated CD30 molecule was lower (5 vs. 21 %). In a cohort of 31 XLA patients, plasma levels of soluble (s)LAG-3 and sCD30, chosen as indirect indicators of the Th1 / Th2 activity in vivo, were significantly higher and lower, respectively, than those measured in 31 healthy controls. Likewise, plasma levels of interferon-inducible protein 10 and of macrophage-derived chemokine in XLA patients were significantly higher and lower, respectively, than in healthy controls.

Polarization of PPD-specific T-cell response of patients with tuberculosis from Th0 to Th1 profile after successful antimycobacterial therapy or in vitro conditioning with interferon-alpha or interleukin-12.

The T helper (Th) 1/Th2 balance in the T-lymphocyte response to purified protein derivative (PPD) was evaluated at the clonal level in six Italian and five Gambian patients with pulmonary tuberculosis (TB) before and after antimycobacterial therapy, as well as in five Gambian and four Italian healthy immune control subjects. In untreated patients, most PPD-specific clones derived from either peripheral blood or pleural effusions showed a Th0 cytokine profile (production of both interferon [IFN]-gamma and interleukin [IL]-4/IL-5). After 6 mo of therapy and clinical healing, most PPD-specific clones showed a polarized Th1 profile (production of IFN-gamma but not IL-4/IL-5) in both Italian and Gambian patients. The Th1 polarization was less marked in Gambian than in Italian patients and failed to occur in another group of four Italian patients who experienced treatment failure. The cytokine profile observed after successful therapy in patients with TB was similar to that found in healthy control subjects. T-cell clones of undefined specificity generated from PPD-stimulated cultures showed a similar Th0/Th2 bias in Gambian individuals and Italian patients with treatment failure. The Th0/Th2-biased responses in Gambian patients before therapy could be modulated in vitro by IFN-alpha or IL-12, which induced a Th1 polarization of both PPD-specific and bystander T cells. Our data show that active TB associates with a predominant Th0 response to mycobacterial antigens that could play a role in the pathogenesis of the disease. Adjunctive immunotherapy using Th1-polarizing cytokines could increase host defense against mycobacteria and accelerate healing.

H(+),K(+)-atpase (proton pump) is the target autoantigen of Th1-type cytotoxic T cells in autoimmune gastritis.

BACKGROUND & AIMS: The proton pump H(+),K(+)-adenosine triphosphatase (H(+),K(+)-ATPase) of parietal cells is the major humoral autoantigen in both human and experimental autoimmune gastritis (AIG) characterized by an inflammatory infiltrate in the gastric mucosa and loss of parietal cells. The aim of this study was to detect H(+),K(+)-ATPase-specific T cells in the gastric mucosa of patients with AIG and to define their functional properties. METHODS: In vivo-activated T cells from the infiltrates of the gastric mucosa of 5 patients with AIG were isolated and cloned. The ability of gastric T-cell clones to proliferate and to produce cytokines in response to H(+),K(+)-ATPase, as well as their expression of B-cell help, perforin-mediated cytotoxicity, and Fas-Fas ligand-mediated apoptosis in target cells, were assessed. RESULTS: A proportion (25%) of the CD4(+) clones from the gastric corpus of AIG patients proliferated in response to porcine H(+),K(+)-ATPase. Most of these clones (88%) showed a Th1 profile, whereas a few secreted both Th1 and Th2 cytokines. Virtually all of the H(+),K(+)-ATPase-specific clones produced tumor necrosis factor alpha and provided substantial help for B-cell immunoglobulin production, and most of them expressed perforin-mediated cytotoxicity against antigen-presenting cells and induced Fas-Fas ligand-mediated apoptosis in target cells. CONCLUSIONS: Activation of proton pump-specific Th1 cytotoxic/proapoptotic T cells in the gastric mucosa can represent an effector mechanism for the target cell destruction in AIG.

Usefulness of (13)C-urea breath test in the diagnosis of gastric helicobacter pylori infection.

Helicobacter pylori chronically infects half of the human population and is associated with gastritis, peptic ulcer and gastric cancer. (13)C-urea breath test (UBT) is the main in vivo tool for the diagnosis of H. pylori infection. In this study, the safety and the accuracy of UBT were evaluated. A group of 492 dyspeptic patients was studied by UBT, the results were expressed as the difference over baseline at 30 min (DOB30). All patients were evaluated for systemic, gastrointestinal or allergic-type adverse reactions after ingestion of 75 mg (13)C-urea and citric acid in aqueous solution. The first 256 patients enrolled also underwent endoscopy and gastric biopsy. Patients positive on histology were considered infected. UBT was well tolerated and none of the 492 patients had any systemic or allergic-type adverse reaction. Among the 256 patients studied with histology, 116 were H. pylori positive on biopsies. Using 4 %o as cut-off value for DOB30,115 out of the 256 patients were positive on UBT, with only 2 false positive and 3 false negative. With this threshold, the sensitivity, specificity, and accuracy of the UBT were 97.4%, 98.5%, and 98.0%, respectively. (13)C-UBT has proven to be a safe and simple, yet accurate, test for the non-invasive diagnosis and monitoring of H. pylori infection.

Some anti-thyroperoxidase antibodies positive sera give a pANCA pattern on ethanol-fixed human neutrophils: cross-reactivity or false positives?

Fifty-six sera from patients with autoimmune thyroiditis and 33 sera from patients with MPO-ANCA were examined in order to ascertain whether a cross reactivity between MPO-ANCA and anti-thyroperoxidase (aTPO) was present. Sera from 20 healthy donors aTPO and aMPO negative were used as control. About 95% of heat inactivated sera from patients with autoimmune thyroiditis and from controls gave positive results (atypical pANCA pattern) on ethanol-fixed neutrophils. The prevalence of positive results was significantly lower when unheated aTPO positive sera were used (17.8%). On the other hand, only 9% of sera with MPO-ANCA were positive on cryostatic sections of human thyroid. Indirect immunofluorescence tests (IF) on human neutrophils with MPO defect were negative with sera from patients with MPO-ANCA, but uninactivated sera with aTPO and positive for pANCA on normal neutrophils showed a very high prevalence of positive results (90%). According to our data only few sera positive for aTPO recognize "normal" MPO, but the majority of sera from patients with autoimmune thyroiditis and positive for pANCA on normal neutrophils recognize also an "abnormal" MPO. On the other hand MPO-ANCA usually recognize epitopes presently only on the normal enzyme, a small proportion of these autoantibodies can react with TPO. Heat inactivated sera give false positive results for pANCA on ethanol fixed human neutrophils.