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C Raykundalia

Publications and source records attributed to C Raykundalia.

15 recordsLinked to original sources
PubMed2000

Hypofibronectinaemia and severity of sickle cell anaemia in Nigeria.

Plasma fibronectin levels in sickle cell anaemia and apparently healthy Nigerians were investigated to determine any correlation with disease severity. A cheaper in-house plasma fibronectin assay was also developed that could be adapted for use in Africa and elsewhere. Plasma fibronectin assay was concurrently carried out using the newly developed inhibition enzyme-linked immunosorbent assay (ELISA) and a commercial competitive binding ELISA. The in-house assay compared favourably with that of the commercial kit. The mean plasma fibronectin levels in sickle cell anaemia subjects were significantly lower than that of control subjects (P < 0.001). Plasma fibronectin concentration could therefore be useful in assessing the severity of sickle cell anaemia.

Adolescent↗
PubMed1999

Compromised OX40 function in CD28-deficient mice is linked with failure to develop CXC chemokine receptor 5-positive CD4 cells and germinal centers.

Mice rendered deficient in CD28 signaling by the soluble competitor, cytotoxic T lymphocyte-associated molecule 4-immunoglobulin G1 fusion protein (CTLA4-Ig), fail to upregulate OX40 expression in vivo or form germinal centers after immunization. This is associated with impaired interleukin 4 production and a lack of CXC chemokine receptor (CXCR)5 on CD4 T cells, a chemokine receptor linked with migration into B follicles. Germinal center formation is restored in CTLA4-Ig transgenic mice by coinjection of an agonistic monoclonal antibody to CD28, but this is substantially inhibited if OX40 interactions are interrupted by simultaneous injection of an OX40-Ig fusion protein. These data suggest that CD28-dependent OX40 ligation of CD4 T cells at the time of priming is linked with upregulation of CXCR5 expression, and migration of T cells into B cell areas to support germinal center formation.

Abatacept↗
PubMed1999

CD4 T cell traffic control: in vivo evidence that ligation of OX40 on CD4 T cells by OX40-ligand expressed on dendritic cells leads to the accumulation of CD4 T cells in B follicles.

We report here that CD40- but not lipopolysaccharide (LPS)-activated murine dendritic cells (DC) express OX40-ligand (OX40L) as has been reported in humans. To understand how OX40 ligation affects differentiation of CD4 T cells at the time of priming, we constitutively expressed OX40L on DC using the DC-specific promoter of CD11c. Transgenic mice showed greatly increased numbers of CD4 but not CD8 T cells in their B cell areas. This effect was to a great extent immunization dependent, as spleen and lymphoid tissue with no germinal center reactions from mice which had not been deliberately immunized did not show marked CD4 T cell accumulation. The increased numbers of CD4+ CD62low cells in transgenic mice suggest that it is activated CD4 T cells that accumulate within B cell follicles. These data are consistent with the notion that physiological engagement of OX40 (CD134) on activated CD4 T cells either initiates their migration into or causes them to be retained in B follicles. In contrast, LPS-treated CD did not up-regulate OX40L expression. This dichotomy provides a molecular explanation of how DC might integrate environmental and accessory signals to control cytokine differentiation and migration in CD4 effector cells.

Animals↗
PubMed1999

Study of the mechanisms of killing of Mycobacterium bovis BCG by apoptosis in J774 murine macrophages.

OBJECTIVE: To determine the relationship between the mechanism of apoptosis and intracellular killing of Mycobacterium bovis BCG. Apoptosis, "programmed cell death"--a physiologically beneficial and distinct form of cell death. SETTING: In vitro study was carried out in murine macrophage cell line J774 that was infected with Mycobacterium bovis BCG in different set of conditions. Percentage of surviving BCG and apoptotic cells was determined. METHODS: IFN-g and/or LPS-activated and non-activated J774 mouse macrophage cells were infected with BCG in a ratio of 1:5. The morphology of the host cells was studied after 4 hours, 24 hours and 48 hours of infection in cytospins stained with Jenner-Giemsa. Surviving bacteria were counted by incorporation of radiolabelled-uridine after cell lysis. RESULTS: Both in the activated and non-activted J774 cultures some cells undergo apoptosis. In cells activated with IFN-g or LPS without BCG, less than 10% of cells were found to be apoptotic. More apoptosis was seen when LPS-activated cells were infected with BCG. In the cells activated with IFN-g or LPS-activated cells the percentage of apoptotic cells was much higher than in non-activated cells or cells activated with either INF-g or LPS alone. After 24 hours culture, without BCG, about 15% of the cells were found to be apoptotic and with BCG infection this increased to 23% (p < 0.01). The level further increased after 48 hours of infection. BCG growth inhibition was observed in both non-activated J774 cells and cells activated with LPS, INF-g or both and was sustained to 48 hours of co-culture. CONCLUSION: It is evident that BCG-infected J774 cells undergo apoptosis in the presence of a high concentration of RNI and/or ROI. During this process the cells shrink considerably in volume with the removal of water that may concentrate toxic products in the cell. The increased concentration of toxic species and the disorganisation of the phagocytic vacuoles may account for the enhanced stasis and/or death of the intracellular micro-organisms. We conclude that host cell apoptosis may arrest the growth and account for the death of the intracellular mycobacterial pathogen.

Animals↗
PubMed1998

CD4 T cell cytokine differentiation: the B cell activation molecule, OX40 ligand, instructs CD4 T cells to express interleukin 4 and upregulates expression of the chemokine receptor, Blr-1.

This report investigates the role of OX40 ligand (OX40L) and its receptor, OX40, expressed on activated B and T cells, respectively, in promoting the differentiation of T helper type 2 (Th2) CD4 T cells. These molecules are expressed in vivo by day 2 after priming with T cell- dependent antigens. Their expression coincides with the appearance of immunoglobulin (Ig)G switch transcripts and mRNA for interleukin (IL)-4 and interferon (IFN)-gamma, suggesting that this molecular interaction plays a role in early cognate interactions between B and T cells. In vitro, we report that costimulation of naive, CD62Lhigh CD4 T cells through OX40 promotes IL-4 expression and upregulates mRNA for the chemokine receptor, blr-1, whose ligand is expressed in B follicles and attracts lymphocytes to this location. Furthermore, T cell stimulation through OX40 inhibits IFN-gamma expression in both CD8 T cells and IL-12-stimulated CD4 T cells. Although this signal initiates IL-4 expression, IL-4 itself is strongly synergistic. Our data suggest that OX40L on antigen-activated B cells instructs naive T cells to differentiate into Th2 cells and migrate into B follicles, where T cell-dependent germinal centers develop.

Animals↗
PubMed1998

Human CD14 mediates recognition and phagocytosis of apoptotic cells.

Cells undergoing programmed cell death (apoptosis) are cleared rapidly in vivo by phagocytes without inducing inflammation. Here we show that the glycosylphosphatidylinositol-linked plasma-membrane glycoprotein CD14 on the surface of human macrophages is important for the recognition and clearance of apoptotic cells. CD14 can also act as a receptor that binds bacterial lipopolysaccharide (LPS), triggering inflammatory responses. Overstimulation of CD14 by LPS can cause the often fatal toxic-shock syndrome. Here we show that apoptotic cells interact with CD14, triggering phagocytosis of the apoptotic cells. This interaction depends on a region of CD14 that is identical to, or at least closely associated with, a region known to bind LPS. However, apoptotic cells, unlike LPS, do not provoke the release of pro-inflammatory cytokines from macrophages. These results indicate that clearance of apoptotic cells is mediated by a receptor whose interactions with 'non-self' components (LPS) and 'self' components (apoptotic cells) produce distinct macrophage responses.

Animals↗
PubMed1997

Serum C-reactive protein and C3 complement protein levels in severely malnourished Nigerian children with and without bacterial infections.

Bacterial infections are the major determinants of fatality in severe protein-energy malnutrition (PEM). Unfortunately, these infections are difficult to diagnose clinically. C-reactive protein (CRP) levels were determined in 17 infected and 10 non-infected Nigerian children with severe PEM and compared with age/sex-matched apparently healthy controls. The aim was to study the response of this acute phase protein to bacterial infections as well as to assess its value in the diagnosis of infections in severe PEM. C3 complement protein levels were also determined in the same group of subjects. The major organisms isolated in samples from these subjects were S. aureus and the coliforms. Mean CRP level in the non-infected children with severe PEM was 13.8 +/- 6.21 mg/l and rose to 159.83 +/- 124.07 mg/l in the presence of infection. The mean value in healthy non-infected controls was 2.01 +/- 0.96 mg/l. The difference in the mean CRP levels between the infected and non-infected PEM children was statistically significant at p < 0.01. The mean difference between the non-infected and the control subjects was not significant. Using a diagnostic level of 20.00 mg/l of CRP gave a sensitivity of 85.0% and a specificity of 80.0%. This CRP level is a useful index of bacterial infections in severe PEM. C3 complement protein was low in the non-infected malnourished group, but rose significantly in the presence of infection to values similar to that of the healthy controls. C3 protein thus behaves as an acute phase reactant in the presence of infection in severe PEM, and does not appear to be consumed, probably due to a deficiency in the early components of the complement cascade. This suggests a role for C3 measurement in the monitoring of bacterial infections in severe PEM.

Bacterial Infections↗
PubMed1996

Candidate antigens for improved serodiagnosis of tuberculosis.

OBJECTIVE: To explore the possibility that an analysis of antibody specificity to separated components of mycobacteria in a group of tuberculous patients may reveal a combination of target antigens whose antibodies could form the basis of a useful serodiagnostic test. DESIGN: Immunoblots of 1-dimensional (SDS-PAGE) and 2-dimensional (isoelectric focusing/SDS-PAGE) separation of antigenic extracts of Mycobacterium tuberculosis H37Rv (MTSE) and M. bovis bacille Calmette-Guérin (BCG) (MBSE) with 52 tuberculous and 59 BCG-vaccinated control human sera were analyzed for band and spot reactivity patterns that are indicative of infection with M. tuberculosis. RESULTS: Reactivity to antigens banding in the 10-18 kDa, 37-43 kDa and 70-90 kDa regions allowed a good discrimination between patients and normal subjects. Patients' sera reacting with antigens in the 22-30 and 70-88 kDa regions differentiated responses to MTSE and MBSE. In 2-D immunoblotting, patients' sera only reacted with antigens separating at approximately pI 6.5/26-28 kDa, pI 4.8/38 kDa and pI 6.5/70-79 kDa position and the responses were specific for M. tuberculosis (MTSE). CONCLUSION: These results provide evidence that a combination of these M. tuberculosis antigens may be a useful basis for developing a diagnostic antibody test. Additionally, they may help to define antigens, and host antibody responses that are specific to one but not the other of the two closely related species.

Antibodies, Bacterial↗
PubMed1996

Study the presence of fibronectin binding protein (FnBp) in tuberculosis (TB) patients by elisa.

Fibronectin-binding protein (FnBp) antigens are a prominent secretory protein of short term culture supernatants of M. tuberculosis and M. bovis (BCG) and is conserved within the genus Mycobacterium. The 30/31 kDa antigen of M. tuberculosis is one of the major secretory molecules and is probably routinely recognised by the host immune system in the early stage of tuberculosis infection. Serum immune complexes, prepared from TB patients and normals, were analysed for the presence of FnBp by ELISA using an anti-30/31 kDa (FnBp) monoclonal antibody (CF8) and by western blotting using Fibronectin-HRP. A significant difference was seen between normals and TB patients (p < 0.05). This test was found to have a specificity of 80% and a positive predictive value of 73%. This is a preliminary finding and the test needs to be evaluated further for its performance on a larger number of confirmed TB patients and controls.

Adhesins, Bacterial↗
PubMed1995

Anti-epithelial (anti-A549) antibodies: their nature, specificity and relevance to transplantation.

Several studies have addressed the possible importance of anti-epithelial cell antibodies in kidney transplantation using the A549 cell line as an in vitro model. In this paper we report our results using for the first time an enzyme-linked immunosorbent assay (ELISA) to detect the anti-A549 cell antibodies. Sera from 129 kidney transplant patients were tested for IgM anti-epithelial cell antibodies directed against the A549 cell line prior to transplantation; only three sera were positive (2.3%). 101 of these patients were then followed-up post-transplantation; sera were collected routinely at 2, 6 and 12 weeks and at the time of rejection episodes. All samples were also tested for cytomegalovirus (CMV) IgM antibodies. Sixteen patients developed anti-A549 IgM antibodies, and there was no correlation with acute graft rejection. Anti-epithelial antibodies showed no binding to sections of normal kidney or biopsies of rejected kidneys. Eleven patients were positive for anti-CMV IgM antibodies. In nine cases both IgM anti-A549 and IgM anti-CMV antibodies were found, which was a highly significant association (p < 0.001). Analysis of A549 cellular proteins by immunoblotting gave evidence for the presence of CMV polypeptides in the cell lysate. Electron-microscopic examination of A549 cell preparations revealed intracellular particles which were compatible in size with CMV. Polymerase chain reaction analysis confirmed the presence of a specific CMV DNA sequence in A549 cells of several batches from different sources. Our data strongly suggest that the A549 cell line used in several published reports is infected with CMV and that in the majority of cases the anti-A549 'anti-epithelial' antibodies found in renal transplant patients are anti-CMV antibodies.

Adolescent↗
PubMed1995

Presence of secretory IgA antibodies to an enteric bacterial pathogen in human milk and saliva.

The concept of a common mucosal immune system in man was tested by examining the concurrent presence of specific-secretory IgA (SIgA) antibodies in human milk and saliva from three groups of subjects: 64 Sri Lankan women living in Sri Lanka; 20 immigrant Asian women living in Birmingham (median duration of residence in the United Kingdom five years); and 75 Caucasian women living in Birmingham (controls). Enzyme linked immunosorbent assays (ELISA) were developed to detect enterotoxigenic Escherichia coli (ETEC) colonisation factor/1 (CFA/1) specific SIgA antibodies in milk and saliva. ETEC CFA/1 specific SIgA antibody activity was detectable in milk (37.5% and 25%) and saliva (42.1% and 35%) of Sri Lankan and immigrant Asian women, respectively, but not in any of the Caucasian controls. Eighty five point two per cent of subjects who were positive had specific antibodies detectable in both milk and saliva; 5% of all Sri Lankan women and 10% of all immigrant Asian women had detectable antibody only in saliva. These observations lend further strong support to the idea that a common mucosal immune system exists in man. The continuing presence of specific SIgA antibodies in Asian immigrants to previously encountered antigens suggests that there may be an 'immunological memory' in the human secretory immune system.

Adolescent↗
PubMed1993

The acquisition of anti-pneumococcal capsular polysaccharide Haemophilus influenzae type b and tetanus toxoid antibodies, with age, in the UK.

Antibody levels specific for capsular polysaccharides of Streptococcus pneumoniae and Haemophilus influenzae type b (Hib) and to tetanus toxoid (TT), were measured in serum samples of 750 age-stratified subjects from the UK. The study subjects comprised healthy adult volunteers and hospitalized children undergoing elective surgery, excluding those with a history of infection or under investigation for immunological or haematological disorders. These antibody levels were calibrated by comparison with serum pool obtained from healthy adult volunteers, who were immunized with Hib polyribose-phosphate vaccine (Merieux). The data are intended to provide reference ranges to assist in the interpretation of specific antibody measurements in the clinical setting. Maternal IgG pneumococcal capsular polysaccharide (PCP) specific antibody levels, geometric-mean titre (GMT) 1/22, were lost by 6 months of age (GMT of 1/9). They remained low until 3-5 years (GMT of 1/20), and consisted principally of IgG1. Thereafter, IgG anti-PCP antibody titres increased steadily to adult levels (GMT of 1/275), of which 80% was IgG2. Anti-PCP antibody titres of the IgM isotype rose steadily from a GMT 1/21 (0-6 months) to 1/420 (3-5 years), a level which was maintained until adulthood. Anti-Hib antibody concentrations, determined by RABA, again demonstrated the decline in maternal antibody, from 0.18 micrograms/ml in the 0-6 month age cohort, to 0.09 microgram/ml between 6 and 12 months. Geometric-mean antibody concentrations remained below 0.2 micrograms/ml until 3-5 years, then increased with age, attaining the mean adult level of 1.02 micrograms/ml. Anti-TT antibody concentrations were measured in the same sera, by ELISA. Two peaks in anti-TT antibody levels were seen in children of 0.059 IU/ml and 0.166 IU/ml corresponding to the schedule of routine childhood immunization in the first year and at 5 years of age.

Adolescent↗
PubMed1992

Effect of blocking TNF-alpha on intracellular BCG (Bacillus Calmette Guerin) growth in human monocyte-derived macrophages.

Four agents, thalidomide, oxpentifylline, dexamethasone and a polyclonal anti-TNF-alpha antibody, were all shown by specific Elisa to block endogenous TNF-alpha production by Bacillus Calmette Guerin (BCG)-infected human monocyte-derived macrophages in in vitro culture. There was however no significant enhancement of intracellular BCG growth, over a 7-day incubation, in human monocyte-derived macrophages in the presence of any of the TNF-alpha-blocking agents, as determined by both radiometric and CFU counting methods of assessing bacterial viability and growth. The result suggests that the action of TNF-alpha alone is unlikely to be an important effector mechanism in antimycobacterial immunity within human cells.

Antibodies↗
PubMed1981

Properties of monoclonal antibodies to human immunoglobulin kappa and lambda chains.

Hybridomas have been produced from mice immunized with human IgG. Culture supernates were assayed for the presence of antibody-producing cells by passive haemagglutination. Hybridomas producing antibodies to human kappa (kappa) and lambda (lambda) light chains have been cloned and grown as ascitic tumours in BALB/c mice. The antigen-binding characteristics of the monoclonal antibodies, contained in the ascitic fluid, were assessed by haemagglutination inhibition, ELISA and radioimmunoassay systems and by the binding of radiolabelled antigen in analytical flat-bed iso-electric focussing gels. One monoclonal anti-kappa reacted better with free than with combined kappa chains; for another the reverse was true. Antibody fractions separated by DEAE chromatography of ascitic fluids were coupled to ox red cells with chromic chloride and compared with polyclonal antibodies for the detection of cell-surface immunoglobulins.

Animals↗