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R Raghupathy

Publications and source records attributed to R Raghupathy.

50 records · Page 3Linked to original sources
PubMed1991

Influence of the genetic background and carrier protein on the antibody response to GnRH.

A vaccine against the gonadotropin releasing hormone (GnRH) is being developed as an immunological method for the treatment of prostatic enlargement. The work described here was aimed at investigating the influence of the genetic background on immune responses to GnRH conjugated to diphtheria toxoid (DT). Mice of different strains were injected with the conjugate and the antibody levels against GnRH and DT quantitated in order to examine the effect of genetic background on immune responses to the hapten and the carrier. All immunized animals produced antibodies to DT. Anti-GnRH antibodies were generated by all strains of mice except 129. The low anti-GnRH response in the 129 strain mice did not appear to be MHC-linked, as C57BL/6 mice, which bear the same MHC haplotype as 129 mice, were able to generate a strong anti-GnRH response. The non-responsiveness to the hapten (GnRH) in 129 strain mice was overcome by the use of an 'alternate carrier' approach.

Animals↗
PubMed1991

Hyporesponsiveness to a GnRH vaccine in a non-responder mouse strain is T-cell mediated.

Immunization of rats and monkeys with the decapeptide gonadotropin releasing hormone (GnRH) linked to carriers such as diphtheria toxoid (DT) or tetanus toxoid (TT) results in a marked atrophy of the prostate. This vaccine is now being explored for its potential in the "immunosurgery" of prostatic hypertrophy in men and is currently undergoing Phase I/II clinical trials. We have been investigating immunogenetic aspects of immune responses to this hapten-carrier conjugate, and in a recent communication we described the responses of different strains of mice to GnRH conjugated to DT (GnRH-DT). Mice of the 129 (H-2b) strain were found to be non-responders to GnRH. However, further immunization of GnRH-DT-immunized 129 mice with GnRH linked to an alternate carrier, TT, resulted in the production of high levels of anti-GnRH antibodies. This showed that 129 mice are not deficient in GnRH-specific B cells and that the lack of response to GnRH in 129 mice is possibly due to (i) the lack of appropriate helper T-cells or (ii) the presence of suppressor cells. In this report we present evidence to support the existence of suppressor cells in GnRH-DT-immunized 129 mice.

Animals↗
PubMed1991

Carrier-induced suppression of the antibody response to a 'self' hapten.

Immunization of male rats and monkeys with gonadotropin-releasing hormone (GnRH) conjugated to a carrier results in a dramatic atrophy of the prostate. GnRH, linked to either diphtheria toxoid or tetanus toxoid as carrier, is now being evaluated for its use in the immunotherapy of hormone-dependent prostate enlargement in men. This report deals with the phenomenon of carrier-induced, epitope-specific regulation in the GnRH-carrier system. In experiments designed to assess the influence of the carrier on antibody responses to the 'self' hapten GnRH, we show that preimmunization with carriers diphtheria toxoid and tetanus toxoid results in a strain-dependent inhibition of anti-GnRH responses in mice. Results of adoptive transfer experiments indicate that T cells from carrier-presensitized mice are responsible for suppression of anti-haptenic antibodies and that T cells from conjugate-immunized mice, on the other hand, can actually help overcome hyporesponsiveness.

Animals↗
PubMed1990

A simplified cellular ELISA (CELISA) for the detection of antibodies reacting with cell-surface antigens.

This paper describes the adaptation of a cellular enzyme-linked immunosorbent assay (CELISA) for the detection of antibodies to cell-surface antigens. This CELISA has the advantages of convenience and rapidity and is therefore ideally suited for the screening of a large number of hybridoma culture supernatants. The basic procedure involves the direct drying of cell suspensions onto the wells of enzyme immunoassay (EIA) plates and a subsequent EIA with appropriate blocking reagents. In order to overcome high background binding of primary antibodies to Fc receptors and of secondary antibodies to surface Ig (sIg), this method involves a blocking step consisting of unlabelled secondary antibodies. Once CELISA plates are prepared, they can be stored for a period of at least 6 months and hence this assay does not rely on the availability of fresh, viable cells for each assay. This assay is simple, reproducible and sensitive. The results can be assessed in an objective manner and can also be adapted for the detection of cellular antigens. This paper describes a CELISA for the detection of antibodies to blood group antigens and human leukocyte (HLA) antigens.

ABO Blood-Group System↗
PubMed1989

Anti-fertility vaccines.

Vaccines are under development for the control of fertility in males and females. This review discusses developments in anti-fertility vaccines at the National Institute of Immunology, New Delhi, India. A single injection procedure for the sterilization or castration of male animals depending on the site at which the injection is given, has passed through field testing and is expected to be on the market in the near future. Vaccines inducing antibodies against the human chorionic gonadotropin have gone through phase I trials with satisfactory results. A vaccine producing a consistently bioeffective antibody response against gonadotropin-releasing hormone is ready for phase I/II clinical trials in patients of carcinoma of prostate after due experimentation in animals and toxicology studies. Research to identify sperm antigens for incorporation into second generation vaccines is in progress.

Animals↗
PubMed1987

Purification and characterization of class II histocompatibility antigens from a homozygous human B cell line.

Human class II histocompatibility antigens were purified from the Epstein-Barr virus-transformed human B lymphoblastoid cell line LG-2 by immunoaffinity chromatography. This is the first time all three subsets have been prepared as nonradioactive materials on a milligram scale. The yields of DR, DQ, and DP from 10 g of cells were approximately 12, 2, and 0.2 mg, respectively. Cross-contamination of the subsets was found to be less than 2% when assayed by measuring the binding of antigen-specific monoclonal antibodies to antigen immobilized on fixed erythrocytes. The three purified subsets were extensively characterized. They contained no detectable invariant chain. The three proteins were distinguished by their migration on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and isoelectric focusing. The denatured antigens were susceptible to partial removal of carbohydrate by endoglycosidase H and apparently complete removal of carbohydrate by endoglycosidase F. The isolated, denatured chains differed in their affinities for radiolabeled lectins, suggesting differences in carbohydrate structures. A water-soluble form of each antigen was prepared by a controlled papain digestion of the native antigen. Both native and denatured antigens were analyzed for their reactivities with a panel of class II antigen-specific monoclonal antibodies, allowing a precise definition of the specificities of the antibodies.

Alkylation↗
PubMed1986

Transfected human B lymphoblastoid cells express the mouse Ad beta-chain in association with DR alpha.

The human EBV-transformed cell line TOM was transfected with plasmid DNA containing a complete genomic copy of the murine class II Ad beta gene. Drug resistant transfectant clones showed cell surface expression of the Ad beta gene product, as detected by flow microfluorimetry when using a mouse monoclonal antibody (MKD6) specific for Ad beta. Immunoprecipitation and two-dimensional gel electrophoretic analysis of the Ad beta-containing molecules from the transfected cells revealed that the mouse beta-chain was expressed in noncovalent association with the human DR alpha-chain rather than with DQ alpha, the human A alpha homologue. The implications of this unexpected pairing for our understanding of the processes controlling the association of class II alpha and beta gene products and of the roles of Ia molecules in normal and pathologic immune function are discussed.

Animals↗
PubMed1985

SB subregion of the human major histocompatibility complex: gene organization, allelic polymorphism and expression in transformed cells.

The SB region of the human major histocompatibility complex (MHC) has been cloned from cosmid and lambda phage libraries made from the human B-lymphoblastoid cell line Priess (DR4/4, DC4/4, SB3/4). Two alpha genes and two beta genes are encoded in the 100 kb long SB region in the order SB alpha-SB beta-SX alpha-SX beta. The SB alpha and SB beta genes encode the alpha and beta subunits of the SB subset of class II MHC molecules. Both the SX alpha and the SX beta genes are pseudogenes in the haplotype examined. From the isolated clones, the two haplotypes of the Priess cell line, SB3 and SB4, are distinguished by nucleotide sequencing and blot hybridization analyses. Restriction site polymorphisms between the SB3 and SB4 clones were observed only in relatively small regions of the SB beta and SX beta genes. A mouse macrophage cell line was transfected with one of the cosmid clones containing both SB alpha and SB beta genes. Expression of the alpha and beta genes was detected by fluorescene-activated cell sorting (FACS) and two-dimensional gel electrophoresis using SB-specific monoclonal antibodies.

Alleles↗
PubMed1984

Fate of antipaternal H-2 antibodies bound to the placenta in vivo.

We have previously demonstrated that the placental spongiotrophoblast and yolk sac venous plexus express paternally derived H-2K and D (class I) antigens in a manner accessible to maternal circulation, and that the placenta serves to prevent antipaternal antibodies from reaching the fetus. Kinetic studies indicated that the placenta is capable of reexpressing its H-2 antigens after having been bound by anti-H-2 antibodies, suggesting that the placental cells somehow have the ability to eliminate the bound antibodies. In order to investigate the fate of the antibodies, we have followed the uptake and fate of radiolabeled anti-H-2Kk monoclonal antibody in the placentas of target allogeneic and control syngeneic pregnancies. Chromatographic analyses indicate that most of the intercellular radiolabel is associated with fragments smaller than IgG, and similar degradation was not observed with syngeneic control placentas. We conclude that the placenta is capable of binding, ingesting, and then digesting antipaternal H-2 antibodies, further substantiating the immunoabsorbent barrier hypothesis of allogeneic fetal survival.

Animals↗
PubMed1982

Characterization and cross-reactivity of human and mouse oncofetal antigens. Use of a new solid phase assay for detection of cell surface antigens.

Oncofetal (OF) antigens have been isolated from mouse F9 teratocarcinoma cells, mouse testicular cells, and human molar tissue by detergent extraction followed by dialysis. The soluble antigens have been used in solid phase radioimmunoassay (SPRIA) and enzyme-linked immunosorbent (ELISA) assay. Specific antibodies have been raised to these antigens in mice. By using these antisera, extensive cross-reactivity was found between mouse and human OF antigens. A human trophoblastic tumor cell line BEWO absorbed out mouse anti-F9 reactivity. Patients with tumors of germinal origin were found to have antibodies which cross-react with mouse and human OF antigens. This new assay is a rapid and sensitive method for the screening of monoclonal antibodies against these antigens as well as for detecting antibodies to tumors bearing these antigens in patients.

Absorption↗
PubMed1981

The ontogeny and turnover kinetics of paternal H-2K antigenic determinants on the allogeneic murine placenta.

In previous reports we provided evidence for the expression of paternal H-2Kk antigens on the placenta, accessible to maternal circulation. We have now examined the ontogeny of paternal H-2Kk antigens in the placenta from day 10 to day 17 of gestation and find a steady increase per gram placenta. In order to substantiate the proposal that the placenta functions as an immunoabsorbent barrier preventing the entry of anti-paternal antibodies to the fetus, we monitored the uptake of monoclonal anti-paternal H-2Kk antibody by target (antigen-bearing) and control fetuses and placentas at various intervals after injection. We have previously shown that F(ab')2 anti-H-2Kk behaves like intact immunoglobulin in placental immunoabsorption studies, and demonstrate here that the peak placental uptake of the antibody is not affected by the removal of the Fc portion, whereas its rate of clearance is increased. In contrast to the anti-H-2Kk antibody, monoclonal anti-I-Ak (specificity 17) antibody (IgG2a) shows no placental immunoabsorption.

Animals↗
PubMedDate not supplied

Modulation of the transforming growth factor beta1 by vitamin E in early nephropathy.

OBJECTIVE: The aim of this study was to investigate the pharmacological activity of an antioxidant, alpha-tocopherol (vitamin E, VE) in streptozotocin-induced diabetic rats and study its role in modulating the transforming growth factor beta1 (TGF-beta1). METHODS: Male Sprague-Dawley rats were treated with streptozotocin to induce diabetes. VE and/or insulin (INS) were administered daily during treatment periods of 3, 5, 7 and 10 days. Plasma glucose and fructosamine were measured in diabetic rats at the end of each treatment period. Samples of plasma, urine and renal cortex were analyzed for changes in protein and lysozyme excretion, reduced glutathione and malondialdehyde formation. TGF-beta1 was determined by ELISA and expression of TGF-beta1 mRNA was investigated by RT-PCR and Northern blot analysis. RESULTS: Diabetes-induced glycemic stress was suppressed by INS, VE or a combination of INS and VE. Diabetes-induced increases of glucose, protein and lysozyme excretion were markedly depressed after 10-day treatment with INS, VE and the combination of INS and VE. Decreased glutathione content in the renal cortex of diabetic rats recovered towards control values, especially after 10-day treatment. Malondialdehyde content increased in diabetic rats and was reduced towards control value following 7- and 10-day treatments. Treatment of diabetic rats with INS, VE or the combination of INS and VE decreased elevated TGF-beta1 in plasma, decreased excretion of TGF-beta1 in urine, and decreased renal cortex TGF-beta1 mRNA levels. CONCLUSIONS: Diabetes-induced overexpression of TGF-beta1 mRNA was suppressed by VE and INS after 5-, 7- and 10-day treatments. The results obtained with the antioxidant VE suggest that oxidative stress is involved in the development of diabetic nephropathy. Therefore, VE treatment may be effective in early stages of diabetic nephropathy to decrease or prevent pathological complications.

Animals↗