Ograniczanie wyników

Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 38

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  immunoglobulin G
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
The determination of the anti-Toxoplasma immunoglobulin G (IgG) avidity is a diagnostic method which has been intensively used for differentiating of recent and more distant Toxoplasma gondii infection in a single serum sample. Finding of low avidity anti-Toxoplasma IgG antibodies usually indicates recently acquired infection, while the presence of high avidity IgG antibodies contradicts to recently acquired infection. Recently, a number of commercial kits have been introduced for determining the avidity of anti-Toxoplasma IgG antibodies. Therefore, it seemed advisable to make comparative studies in order to investigate the correspondences and discrepancies in the results obtained by the different kits. We compared and analysed the results obtained with four commercially available anti-Toxoplasma IgG avidity assays. They were expected to give well correlated results, but some differences between the kits were observed in the ranking of anti-Toxoplasma IgG avidity ("high" or "low" or "borderline"). Among others, differences in the dilution method or differences in the type, quality or quantity of the Toxoplasma antigen used in the different assays might explain the observed divergences.
Significant protease activity has been detected in somatic extract of adults and microfilarial stage of Setaria cervi, using general protease substrates and collagen. The pH optima studies of the somatic extract of adult females showed two peaks at 7.0 and 5.0 for collagenase activity. Both forms were purified using sequential DEAE-sepharose and Sephadex G-100 column chromatography. The purified enzymes had the molecular masses of 175 and 20 kDa and pH optima at 7.0 and 5.0, respectively. The 175 kDa collagenase was more sensitive to metal chelators and serine protease inhibitors. However, 20 kDa collagenase was sensitive to cysteine protease inhibitors. The IgG antibodies from W. bancrofti infected human sera inhibited both enzymes. Further the purified collagenases were used to digest total human IgG at their respective pH and for different lengths of time. The 175 kDa protein was capable of cleaving human IgG. The digestion appeared to be restricted to a single cleavage point of H-chain within the hinge region of IgG molecule and produced fragments of similar molecular mass (27 kDa) indicating cleavage to Fab and Fc fragments. The degree of digestion was found to be proportional to the incubation time at 37°C. No further digestion of either fragments were observed. The L-chains were apparently resistant to collagenase digestion in all cases. Thus, the results suggest that S. cervi collagenase might be involved in the defense mechanisms of the parasite against the immune response of the host.
11
72%
Different clinical outcomes of tuberculosis (TB) are related to the balance between cell-mediated and humoral immunity and may depend on environmental and individual factors including age and sex. The purpose of this study was to analyze the humoral immune response to recombinant and native mycobacterial antigens in relation to clinical presentations of pulmonary TB in children. We examined 224 serum samples including 81 primary and 31 postprimary TB cases, 30 cases of latent TB infection, and 82 nontuberculosis controls. Commercially available ELISA assays detecting IgG, IgA, and IgM against antigens: 38 kDa, 16 kDa, 38kDa, lipoarabinomannan (LAM), and A-60 were used. The results indicate that IgG production was very low in primary compared with postprimary TB (P<0.0001). IgM levels did not differ between the examined groups. Antibody levels strongly depended on the child's age. In infants aged below 1 there was no difference in the antibody level between the TB and control cases. Most positive cases were observed in children aged above 10. The influence of BCG vaccination on the antibody level was not seen. In all subgroups, person-to-person heterogeneity of antigen recognition was observed. We conclude that humoral immune response is associated with the phase of TB and is stronger in more advanced TB forms. IgG and IgA production against mycobacterial antigens is very low in young children.
Resistance to tuberculosis (TB) is cell-mediated but a humoral response is common and may be correlated with the lack of effective local cellular defense mechanisms. The goal of the study was to evaluate IgG, IgA, and IgM-mediated humoral immune response against 38-kDa+16-kDa and 38-kDa+lipoarabinomannan (LAM) mycobacterial antigens in bronchoalveolar fluid (BALF) from patients with pulmonary TB. Non-tuberculosis (NTB) patients were used as control. 179 BALF samples (56 TB and 123 NTB) were examined. Commercially available ELISA-based assays against proteins 38-kDa and 16-kDa or 38-kDa plus LAM were used. Three different dilutions of BALF: 1:1; 1:10, and 1:50 (100) were tested. Only the results obtained with the 1:10 dilution allowed distinguishing TB and NTB groups. The mean IgG level for 38-Da+LAM was significantly higher in the TB than that in the NTB group (P<0.0001). The mean IgA level for 38-kDa+LAM also was higher in the TB group (P<0.05). No difference was observed between TB and NTB groups in the titer of IgM antibodies. These findings indicate that TB is associated with the presence of detectable levels of antibodies in BALF. The antibody response is highly heterogeneous. This phenomenon results from the balance between pathogen and host immune system. The tests examined for detection of IgG in BALF can be used in combination with other diagnostic methods to increase diagnostic accuracy of pulmonary TB.
Although multiple vaccine strategy for lymphatic filariasis has provided tremendous hope, the choice of antigens used in combination has determined its success in the previous studies. Multiple antigens comprising key vaccine candidates from different life cycle stages would provide a promising strategy if the antigenic combination is chosen by careful screening. In order to analyze one such combination, we have used a chimeric construct carrying the well studied B. malayi antigens thioredoxin (BmTRX) and venom allergen homologue (BmVAH) as a fusion protein (TV) and evaluated its immune responses in mice model. The efficacy of fusion protein vaccine was explored in comparison with the single antigen vaccines and their cocktail. In mice, TV induced significantly high antibody titer of 1,28,000 compared to cocktail vaccine TRX+VAH (50,000) and single antigen vaccine TRX (16,000) or VAH (50,000). Furthermore, TV elicited higher level of cellular proliferative response together with elevated levels of IFN-γ, IL-4 and IL-5 indicating a Th1/Th2 balanced response. The isotype antibody profile showed significantly high level of IgG1 and IgG2b confirming the balanced response elicited by TV. Immunization with TV antigen induced high levels of both humoral and cellular immune responses compared to either cocktail or antigen given alone. The result suggests that TV is highly immunogenic in mice and hence the combination needs to be evaluated for its prophylactic potential.
The results present in this study suggest that the Toxoplasma gondii recombinant ROP1 antigen in an IgG avidity test can be useful for detection of acute stage of infection. Specific antibodies of low avidity were detected in most of the sera from individuals with acute toxoplasmosis, while the absence or specific antibodies of high avidity were detected in sera from patients with chronic infection.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.