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Biomedical subjects

N K Mehra

Publications and source records attributed to N K Mehra.

At least 55 records · Page 3Linked to original sources
PubMed1996

Direct role of HLA-B5 in influencing susceptibility to Takayasu aortoarteritis.

To investigate genetic factors involved in the pathogenesis of Takayasu arteritis (TA), North Indian patients belonging to the states of Punjab, Haryana, Uttar Pradesh and Delhi were examined for HLA-class I and class II antigens and the data compared with healthy controls from the same ethnic group. Additionally, DNA typing was performed using polymerase chain reaction/sequence specific oligonucleotide probe (PCR-SSOP) technique to evaluate the distribution of molecular alleles in the healthy Indian population as compared to orientals and Western caucasoids. The frequency of HLA-B5 was significantly increased in patients as compared to controls (chi 2 = 32.5, corrected P value, Pc = 3 x 10(-6), relative risk = 4.3). Serological splitting of B5 into B51 and B52 did not reveal an association with any of the two subtypes. Weak association was also noticed with DR8 in the patient group (chi 2 = 8.2, Pc = 0.05). Distribution of the molecular subtypes of various HLA-B and DR alleles indicated that although the Indian population is essentially caucasoid, it comprises of an admixture of both caucasoid as well as oriental alleles/haplotypes. The observations clearly suggest that (a) HLA-linked genes are involved in the development of Takayasu arteritis, and (b) rather than a subtype of B5, the whole molecule or its closely linked gene(s) influence susceptibility to TA.

Adolescent↗
PubMed1996

Anti-IgG autoantibodies and possible immune regulatory mechanisms in patients with pulmonary tuberculosis.

SETTING: Anti-Ig antibodies are known to have important clinical and biological implications. OBJECTIVES: To determine naturally occurring anti-F(ab')2 gamma and anti-Fc gamma antibodies in patients with pulmonary tuberculosis (PTB) in relation to various clinical manifestations and human leukocyte antigen (HLA). DESIGN: Antibodies to F(ab')2 and Fc portions of IgG were detected in the sera of normal healthy individuals (n = 41), patients with pulmonary tuberculosis (n = 50) and their household family contacts (n = 20) using an enzyme immuno assay (EIA) system. RESULTS: As compared to controls (0.110 +/- 0.01 optical density [OD]), the levels of anti-F(ab')2 gamma were significantly increased in PTB patients (0.998 +/- 0.08 OD, P < 0.0001) and in their contacts (0.486 +/- 0.04 OD, P < 0.001) suggesting that the occurrence of these autoantibodies is related to infection/exposure to Mycobacterium tuberculosis. Anti-F(ab')2 gamma antibodies were significantly increased in both sputum positive and negative patients (P < 0.0001) and no deviation was observed between these two groups. The levels of these antibodies were positively correlated with disease severity assessed by chest X-ray. The drug failure patients had higher activity of anti-F(ab')2 gamma than drug responders and no impact of anti-tuberculosis chemotherapy was observed. A statistically significant increase of anti-F(ab')2 gamma levels (1.25 +/- 0.21 OD) was observed in HLA-DR2 positive patients as compared to the DR2 negative groups (1.02 +/- 0.09 OD), P < 0.01. No deviation was observed in the levels of anti-Fc gamma levels between controls and any group of PTB patients. CONCLUSION: The present data suggests that the elevated levels of anti-F(ab')2 gamma antibodies in PTB patients represent an anti-idiotypic antibody response to anti-M. tuberculosis antibody caused by an immune imbalance following M. tuberculosis infection.

Antibodies, Anti-Idiotypic↗
PubMed1996

Correlation of serum interleukin-2 receptor-alpha levels with clinical manifestations in pulmonary tuberculosis.

SETTING: The analysis of serum levels of soluble interleukin-2 receptor alpha (sIL-2R-alpha) is an indirect method of studying the in vivo state of immune activation, particularly in patients with pulmonary tuberculosis (PTB) where the disease is associated with cellular immune reactions. OBJECTIVE: To quantitate the serum sIL-2R-alpha in patients and correlate with disease activity. DESIGN: The levels of sIL-2R-alpha were determined using ELISA in serum samples from untreated patients with PTB (n = 107), 30 of whom were later tested during treatment, household family contacts (n = 38), and healthy controls (n = 22). RESULTS: Concentrations of sIL-2R-alpha were significantly higher in PTB patients than in controls (2845 +/- 187 vs 1217 +/- 80 pg/mL, P < 0.0001), and were even more pronounced in the sputum positive (3200 +/- 148 pg/mL) and treatment failure (3335 +/- 196 pg/mL) groups of patients. However, in household family contacts, the sIL-2R-alpha levels were found to be similar to those of healthy controls. The sIL-2R-alpha levels correlated positively with disease activity as assessed by roentgenographic findings. In six of the 16 responder patients, the sIL-2R-alpha levels fell from 3228 +/- 144 pg/mL to 1497 +/- 131 pg/mL (P < 0.0001) after 3 months of successful treatment with anti-tuberculosis drugs. However, no significant change was observed in the treatment failure patients even after one year of chemotherapy with second-line drugs. CONCLUSION: These studies indicate that determination of serum concentrations of sIL-2R-alpha is a sensitive and specific method for monitoring disease activity in terms of T cell activation in pulmonary tuberculosis.

Adult↗
PubMed1996

Polymerase chain reaction--based sequence-specific oligonucleotide hybridization analysis of HLA class II antigens in pulmonary tuberculosis: relevance to chemotherapy and disease severity.

HLA antigens were studied by serology and polymerase chain reaction-based sequence-specific oligonucleotide hybridization techniques in 153 patients with pulmonary tuberculosis (PTB) and 289 healthy controls. HLA-DR2 was present more frequently in PTB patients than in controls (51% vs. 36.3%; corrected P[Pc]=.029, relative risk [RR] = 1.8). The DR2 association was stronger in patients in the drug-failure group (n=56; Pc=.000012, RR=3.7) than in healthy controls and in patients in the drug-responder group. No significant deviation was observed in HLA allelic frequencies in various patient groups, as determined by radiographs of lung lesions. Molecular subtyping of DR2 revealed that the bulk of the allele was DRB1*1501 and DRB1*1502 in patients and controls. There was no skewing of the frequency of these molecular subtypes of DR2 in patients, suggesting that the whole DR2 molecule or its closely linked gene(s) may be involved in governing patient susceptibility to PTB and, particularly, development of the severe drug-resistant form of the disease.

Adult↗
PubMed1996

MHC class II alleles and haplotypes in patients with pemphigus vulgaris from India.

Pemphigus vulgaris (PV) is a blistering disease of the skin and mucous membranes characterized by an autoantibody response against a keratinocyte adhesion molecule, desmoglein 3, causing acantholysis and blister formation. We compared high resolution MHC class II alleles and haplotype frequencies (HLA-DRB, DQA1 and DQB1) in 37 patients with PV to 89 haplotypes of normal relatives from New Delhi and Ahmedabad. We found that PV patients had significantly increased frequencies of DRB1*1404 (P < 0.0001), DQA1*0101 (P = 0.001), and DQB1*0503 (P < 0.0001). These associations were due to the increased frequencies of the haplotype HLA-DRB1*1404, DRB3*0202, DQA1*0101, DQB1*0503 in patients compared to control haplotypes (p < 0.0001). Also, patients from Ahmedabad had a significant increase in HLA-DQB1*0302 (p = 0.03). An identical amino acid sequence (Leu-Leu-Glu-Arg-Arg-Arg-Ala-Glu), in positions 67-74 of the beta domain of DRB alleles is restricted to some DR14 alleles. Therefore, there are three possible explanations for class II allele involvement in autoantibody in PV patients with class II haplotypes marked by HLA-DR14. First, the class II alleles could be markers for an unidentified susceptibility gene in linkage disequilibrium with them. Second, the primary association could be with DQB1*0503 and the association with HLA-DR14 alleles would be the result of linkage disequilibrium. Third, the HLA-DRB1 locus susceptibility could involve a specific amino acid sequence in the third hypervariable region shared by several HLA-DR14 alleles.

Alleles↗
PubMed1995

Results of conversion from triple-drug to double-drug therapy in living related renal transplantation.

Results of 34 recipients of living related renal allografts initially treated with cyclosporine, azathioprine, and prednisolone and later electively converted to AZA and PRED are presented. Thirteen (group A), 14 (group B), and 7 (group C) patients were converted before 9 months, between 9 and 12 months, and after 12 months, respectively. Thirty-four patients who were on AZA and PRED and had never received CsA served as controls. Of the 34 patients, 33 were HLA haploidentical with their donors and 1 was HLA identical. All patients received a mean 8.62 +/- 7.39 third-party blood transfusions. In the control group, 29 patients received haploidentical grafts. The number of blood transfusions given to this group was 7.09 +/- 9.13. Of the 34 patients receiving triple-drug therapy, 9 (26%) had acute rejection within 3 months after conversion, as compared with 5 (14.7%) in the control group (P > 0.05). Although 1 case had acute rejection before conversion, all recipients had stable graft function at the time of conversion. Of these 9 recipients, 7 had conversion over 4-7 weeks, while 2 had rapid conversion. Following treatment of the rejection episodes, 4 patients in the study group responded to therapy, as compared with 3 cases in the control group (P > 0.05). After a mean follow-up of 18.62 +/- 10.31 months (range 3-41 months) following conversion, 4 patients were normal, 4 had chronic rejection (mean serum creatinine = 3.0 mg/100 ml), and 1 was back on regular dialysis. Eventually, of the 34 patients who were converted from triple-drug to double-drug therapy, 25 were normal, 5 had stable chronic rejection, 2 were back on regular dialysis, 1 was retransplanted, and 1 died due to failed graft. At the end of follow-up, graft survival in the study group was 88.2%, as compared with 85.5% in controls (P > 0.05). We conclude that conversion from triple-drug to double-drug therapy is not without risk, even in living related primary renal transplantation. Degree of HLA matching, number of pretransplant blood transfusions, and rejection before conversion did not have any significant effect on rejections following conversion, and the graft loss following conversion is unpredictable.

Adolescent↗
PubMed1995

Influence of anti-IgG antibodies on graft outcome in live related donor renal transplantation.

To study the role of pretransplant IgG anti-F(ab)2 gamma and IgG anti-Fc antibodies on the outcome of live related donor (LRD) kidney transplantation, serum samples from 60 recipients and 20 normal controls (NC) were tested using enzyme immunoassay. Patients with well-functioning grafts (WFG) after 1 year of follow-up had significantly higher IgG anti-F(ab)2 gamma activity expressed as mean optical density measured at 405 nm, i.e. 0.426 +/- 0.06 as compared to NC (0.167 +/- 0.046) or patients undergoing reversible rejection (RR) (0.145 +/- 0.043) and irreversible rejections (IR) (0.26 +/- 0.01). However, patients with IR had higher IgG anti-Fc activity (0.424 +/- 0.2) than the WFG group (0.1 +/- 0.02) and NC (0.095 +/- 0.02), with the RR group values in between (0.248 +/- 0.06). The same trend was observed when the data were analysed according to the serum creatinine levels. We conclude that in the LRD renal transplant situation, pretransplant serum IgG anti-F(ab)2 gamma activity has a protective effect on graft survival while IgG anti-Fc has a detrimental effect on graft outcome.

Antibodies, Anti-Idiotypic↗
PubMed1995

Profile of HLA-B27-related 'unclassifiable' seronegative spondyloarthropathy in females and its comparison with the profile in males.

Unclassifiable seronegative spondyloarthropathy (SSA) syndrome is primarily considered to be an affliction of males. In this report from northern India, 25 HLA-B27 antigen positive females with this condition are described and compared with 39 HLA-B27-positive males with the same disease. All these patients presented with typical features of spondyloarthropathy such as predominantly lower limb synovitis, enthesopathy and inflammatory spinal pain. The onset was insidious in 56% of the females and in 64% of the males. The mean age of onset as also the mean duration of symptoms prior to diagnosis were significantly higher in females (26.2 vs 19.4 yr and 8 vs 2 yr, respectively). A mono- or oligo-arthritis was seen in 52% of the females and in 53% of the males, but the average number of joints involved was less in females (4.8 vs 7.7). Lower limb joints alone were involved in 56% of the females and 49% of the males, with the knees, ankles and hips being most commonly involved, often asymmetrically. The mean degree of symmetry was significantly lower in females (62 vs 76). Ninety-two per cent of females and 74% of males had inflammatory spinal pain. Radiographic sacroiliitis was demonstrable in 56% females and 74% males. It is concluded that 'unclassifiable' SSA syndrome is not infrequent in females but is diagnosed late. Fewer joints tend to be involved and there is greater tendency towards asymmetry in females.

Adolescent↗
PubMed1995

HLA-B27 subtypes in Asian patients with ankylosing spondylitis. Evidence for new associations.

The aim of this study was to investigate the contribution of the different B27 subtypes to ankylosing spondylitis (AS) susceptibility. The polymerase chain reaction (PCR) in combination with the sequence-specific oligonucleotide probes (SSOs) was used to analyse the polymorphism in exon 2 and 3 of HLA-B27 in two Asian groups with different genetic HLA structures: Indian (I) and Thai (T) populations. The same number of AS patients (45) and healthy B27 positive donors (n = 17) from both populations were analysed in order to ascertain the B27 subtypes. Three different findings can be concluded from this study: 1) B*2707 has been found to be associated with AS in both populations. This association has not been previously reported in either ethnic group. 2) B*2704 is strongly associated with AS in the Thai patients (91% in AS vs. 47% in C; RR = 11.5; EF = 0.83). In contrast, B*2704 was found with similar frequency in Asian Indians AS patients and controls (41% in AS vs. 41% in C.). 3) B*2706 was found overrepresented in control populations and absent in AS patients (0% in AS vs. 47% in C.; pc < 10(-6)) showing the maximum value of protective fraction (PF = 1). The B*2706 negative association with AS has not been previously described in other ethnic groups and could indicate a protective effect of this subtype on AS susceptibility. The B*2706 allele has two changes relative to B*2704 at residue 114 (His to Asp) and 116 (Asp to Tyr) in the pockets D/E. The importance that these differences can play in the pathogenesis of AS are discussed.

Amino Acid Sequence↗
PubMed1995

Clinical profile and course and outcome of late acute rejection episodes in living-related-donor renal allograft recipients.

We prospectively monitored clinical data and renal function at monthly intervals in 165 patients who had received living-related-donor renal allografts in our institution between January 1981 and December 1991 and had a functioning allograft for 1 year or longer. During a mean follow-up period of 47.2 (range 13-155) months, 32 patients (17.2%) developed late acute rejections, of which 14 (43.7%) were asymptomatic. Amongst the symptomatic late acute rejections, worsening of hypertension was the commonest finding, being present in 11 (61.1%) patients, followed by oliguria in 8 (44.4%) and weight gain in 7 (38.8%) patients. Of these 32 late acute rejections, as many as 28 (87.5%) showed a response to antirejection therapy with high-dose steroids: 5 (15.6%) a complete response and 23 (71.9%) a partial response. The response rate was 100% if it was the first acute rejection (20% complete and 80% partial), 78.6% if it was the second (14.3% complete and 64.3% partial), and no or only a partial response to treatment if it was the third acute rejection episode. On long-term follow-up, patients who had responded to to antirejection treatment had a significantly better graft survival as compared with nonresponding patients: 76 and 27%, respectively. Our observations suggest that routine monitoring of the renal function at frequent intervals is essential for early diagnosis and treatment of acute rejections, even during the late posttransplant period. The chances of a response to antirejection therapy are higher during the first episode of late acute transplant rejection as compared with second or a third late rejection event.

Acute Disease↗
PubMed1995

Variants of HLA-DR2/DR51 group haplotypes and susceptibility to tuberculoid leprosy and pulmonary tuberculosis in Asian Indians.

This study reports our observations on the correlation between HLA-DR2 subtypes and their DR-DQ haplotypes in patients with tuberculoid (TT) leprosy and pulmonary tuberculosis (PTB). DRB1*1501 was significantly increased in patients with PTB (90%) as compared to controls (p < 0.05); whereas the prevalence of DRB1*1502 was significantly increased in patients with TT leprosy (p < 0.05), suggesting allele-specific binding of the pathogen to form disease-causing motifs to the T-cell receptor. Among DR2-DQ haplotypes, the deviation was noted in the distribution of unique and common haplotypes in patients with TT leprosy and PTB. A significant decrease of haplotype DRB1*1501-DRB5*0101-DQA1*0102-DQB1*0502 in TT leprosy and a significant increase of DRB1*1501-DRB5*0101-DQA1*0103-DQB1*0601 in PTB patients were observed. The occurrence of specific DR2 subtypes and their haplotypes in the two disease groups suggests their involvement in disease pathogenesis.

Adult↗
PubMed1995

CD4+ T-cell responses to recombinant hsp65 and hsp18 of M. leprae and their trypsin-digested fragments in leprosy: diversity in HLA-DR restriction.

Mycobacterium leprae heat-shock proteins hsp65 and hsp18 have received immense attention as major T-cell target antigens in leprosy. Both of these hsps and their tryptic fragments were characterized for their ability to stimulate CD4+ T cells derived from polar leprosy cases and healthy contacts. The optimal digestion of hsps with trypsin yielded four fragments of hsp65--TDB65-1 (24 kDa), TDB65-2 (18 kDa), TDB65-3 (17 kDa), TDB65-4 (14 kDa)-- and three of hsp18--TDB18-1 (10 kDa), TDB18-2 (5 kDa), TDB18-3 (3 kDa). While all of these tryptic fragments and undigested hsps triggered CD4+ T cells from tuberculoid (TT) leprosy patients and healthy contacts (SI > 2), only two fragments--TDB65-2 and TDB18-3--were found to be stimulatory in anergic lepromatous (LL) leprosy patients (SI = 5.27 and 3.0, respectively). Blocking studies using allele-specific anti-DR monoclonal antibodies revealed multiple HLA-Dr restriction, with DR2 providing the strongest restriction in both TT as well as LL leprosy. These findings indicate that M. leprae hsps and their trypsin-digested fragments are promiscuous and recognizable in the context of diverse HLA alleles, of which DR2 is the most efficient restriction element. The 18-kDa fragment of hsp65 and the 3-kDa fragment of hsp18 are the most versatile fragments that could elicit in vitro proliferation in both polar forms of leprosy.

Antibodies, Monoclonal↗
PubMed1994

Asian Indian HLA-DR2-, DR4-, and DR52-related DR-DQ genotypes analyzed by polymerase chain reaction based nonradioactive oligonucleotide typing. Unique haplotypes and a novel DR4 subtype.

We have employed a PCR-based nonradioactive technique using biotinylated SSOPs to define HLA-DR2-, 4-, DR51-, and DR52-associated DR-DQ genotypes in Asian Indian families. In the DR2 group, most haplotypes described by us in a previous study were confirmed by family analysis. Evidence for one additional haplotype was available in this study. The classic DRB1*1501- and DRB1*1502-associated caucasoid haplotypes occurred with an appreciable frequency in Asian Indians, but two of the DRB1*1601-associated Caucasoid haplotypes were absent. At least six unique and unusual DR2-associated genotypes were encountered. In the DR52 group, the three most common alleles are DRB1*0301, DRB1*1404, and DRB1*1101. The DR6-associated alleles were DRB1*1301, 1302, 1401, and 1404. A few unique haplotypes occurred with low frequency in this group. In the DR4 group, at least three unusual patterns of hybridization were noticed by family analysis. One of these appears to be a novel DR4 subtype upon sequencing. These results demonstrate that, besides HLA-DR2, appreciable complexity occurs in the DR4- and DR52-associated alleles among Asian Indians. The presence of unique DR-DQ haplotypes in addition to those found characteristically among Western Caucasians suggests that the Indian population provides valuable source of many HLA class II haplotypes.

Amino Acid Sequence↗
PubMed1994

Effect of panel reactive antibody on live related donor kidney transplantation: Indian experience.

Serum samples from 95 recipients, transplanted with kidneys from live related donors, were tested for the presence of panel reactive antibodies (PRA) in pre- and post-transplant serum samples by the extended microdroplet lymphocytotoxicity test. The immunoglobulin class of antibodies was tested by treatment of serum with dithiothreitol. A significant correlation was found between the high PRA found in the 75 pretransplant sera tested and the subsequent rejection episodes. In addition, the level of pretransplant PRA activity was associated with graft survival in that patients with low PRA had significantly superior graft survival than those with high PRA. Furthermore, the present data show that patients with historical high PRA, but current low PRA, had graft survival similar to that in recipients who had moderate PRA in their current sera. High PRA patients had more often a positive crossmatch than patients with low PRA. The PRA level was also associated with prolonged waiting period. Immunoglobulin class of antibodies was related to graft acceptance in that the presence of IgM antibodies was not detrimental to transplantation. The results in the present study suggest that PRA of < 10% is negligible, while more attention should be paid to patients with PRA > 10%.

Adolescent↗
PubMed1994

Pemphigus in Oxford, UK, and New Delhi, India: a comparative study of disease characteristics and HLA antigens.

A study of pemphigus in New Delhi, India, and Oxford, UK, was undertaken including 20 patients in Oxford and 50 in New Delhi. Data included clinical and histological subtypes and socio-economic data; patients were HLA typed. In New Delhi pemphigus vulgaris predominated, but in Oxford pemphigus vulgaris and pemphigus foliaceus have equal prevalence. Disease distribution with sex was the same, but age at onset was significantly lower in New Delhi (p = 0.0019). HLA typing in pemphigus vulgaris patients revealed a significant reduction in HLA-DR2 in New Delhi (p = 0.0008) and Oxford (p = 0.09). A small increase in HLA-DR1 and -DR4 was found in both groups and, in males only, a subtle increase in HLA-DR6 and reduction in HLA-DR3. No differences were found in the class I antigens. Thus there are striking differences in the types of pemphigus between the two populations, yet the genetic predisposition is the same.

Adolescent↗
PubMed1994

Effect of D-penicillamine on lymphocyte subsets: correlation with clinical response in rheumatoid arthritis.

We studied the effects of D-penicillamine (DP) on the clinical response, immunoinflammatory parameters and the lymphocyte subsets in 46 patients with rheumatoid arthritis (RA). Patients were evaluated before the start of the drug and then at 3 and 9 months during the follow up. 38 of 46 (82.6%) patients could continue DP treatment for over 9 months, while in 8 the drug was withdrawn due to adverse effects. Improvement in the various disease activity indices of more than 50% (responders) was seen in 25 of 38 (65.8%) patients. Responders showed a significant decrease in the serum IgA and IgM at 9 months, and in IgM only at 3 months. The serum levels of C3 and C4 did not show any significant change. Serum levels of C-reactive protein and rheumatoid factor (RF) showed a significant decrease at 3 and 9 months. A significant decrease in CD3+ and CD4+ lymphocytes along with a fall in CD4+/CD8+ lymphocyte ratio was also seen in responders at 3 and 9 months, compared to the baseline. Our results suggest that DP may have immunomodulatory action in RA.

Adolescent↗