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J N Agrewala

Publications and source records attributed to J N Agrewala.

31 records · Page 2Linked to original sources
PubMed1996

Antigen incorporation into liposomes results in the enhancement of IL-4 and IgG1 secretion: evidence for preferential expansion of Th-2 cells.

Liposomes have been used to modify the immunological behaviour of a number of antigens. The present study was designed to evaluate the effect of liposomization of ovalbumin on the induction of Th-1 and Th-2-cell response by monitoring the secretion of lymphokines and IgG Isotypes. Liposomes having varied physicochemical properties (positively and negatively charged, neutral and pH-sensitive) were used for this purpose. Ovalbumin delivered in this way induced preferential secretion of IL-4 and production of antigen-specific IgG1 isotypes. This was observed irrespective of the surface charge properties of the liposomes. Further, the concentration of antigen required for the activation of Th cells was 10(2)- to 10(3)-fold lower after encapsulating it in liposomes. These results suggest that liposomes may prove useful adjuvants to prime Th2-like immune responses.

Animals↗
PubMed1995

A 38-kDa antigen of Mycobacterium tuberculosis predominantly induces the secretion of interleukin-2, interferon-gamma and IgG2a antibodies.

In the present study, mice of 3 different haplotypes (H-2d, H-2k and H-2b) were sensitized subcutaneously with heat-killed H37Ra or 38-kDa antigen of Mycobacterium tuberculosis. Lymphocytes obtained from immunized animals were challenged in vitro with 38-kDa antigen in both cases. The dominant pattern of Th1-like lymphokines (IL-2 and IFN-gamma) and preferential production of 38-kDa specific IgG2a-type antibody were observed. It was noted that 38-kDa antigen was recognized permissively by all 3 strains of mice used in the present study. It was interesting to note that C3H/HeJ mice, which express BCG-resistant alleles showed a higher level of proliferative as well as cytokine response as compared to BALB/c and C57BL/6 mice, which bear BCG-susceptible alleles. These results suggest that not only in recall responses but also during the induction as well as expression phase of the immune response mediated by 38-kDa antigen of M. tuberculosis the Th1-like immune response predominates.

Animals↗
PubMed1994

Antigen-specific early primary humoral responses modulate immunodominance of B cell epitopes.

Accumulation of primary Abs against two distinct epitopes on a designed polypeptide, MEP-1, was examined. The early primary response was predominantly against a C-terminal epitope (MEP 77-100), although subsequent maturation established an epitope within the N-terminal half (MEP 17-31) as the immunodominant one. Inversion of immunodominance correlated with the inability of anti-MEP 77-100 B cells to interact productively with T cells, which consequently received reduced help. Interaction between epitope-specific B and T cells was found to be attenuated in the presence of early primary anti-MEP-1 antiserum, and the extent of inhibition was directly proportional to the level and affinity of epitope-specific Igs. Therefore, it seems that early primary Abs to a multideterminant Ag selectively down-regulate maturation of epitope-specific primary humoral responses.

Amino Acid Sequence↗
PubMed1994

A 150-kDa molecule of macrophage membrane stimulates interleukin-2 and interferon-gamma production and proliferation of ovalbumin-specific CD4+ T cells.

In the present study, we describe the potential co-stimulatory role of a macrophage membrane-associated protein of 150 kDa (M150). The protein was isolated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was found to be a single molecule on two-dimensional gel electrophoresis. The molecule was re-constituted in phosphatidyl choline vesicles and tested for its ability to promote the proliferation and the secretion of lymphokines from T helper (Th) cells. The reconstituted M150 induced a significant proliferation of anti-CD3 monoclonal antibody (mAb)-stimulated ovalbumin-specific CD4+ T cells. Further, Th cells activated with this molecule in the presence of anti-CD3 mAb mainly secreted interleukin (IL)-2 and interferon-gamma but not IL-4. M150 could not promote the proliferation of Th cells, or lymphokine secretion in the absence of anti-CD3 mAb. These observations suggest that M150 acts by selectively activating a Th1-like immune response.

Animals↗
PubMed1994

Method for determining the affinity of monoclonal antibody using non-competitive ELISA: a computer program.

A simple and reliable method based upon law of mass action for calculating affinity of a monoclonal antibody using non-competitive ELISA, is described. In this method, the binding of an antibody (Ab) with an antigen (Ag) is measured by ELISA using serial dilutions of both antigen (coated on the plate) as well as antibody. When the OD measured after the antigen antibody interaction was plotted against the concentration of Ab, added to the wells, a hyperbolic curve was obtained. The OD, at any point of the curve, was considered as a direct reflection of the amount of antibody bound to the antigen. The OD-100 denotes the occupancy of maximum no. of epitopes available on the antigen molecules, accessible to the antigen. The concentration of antibody (Ab, Ab') at corresponding levels of antigen concentration (Ag, Ag'), presents the value obtained at OD-50. The [Ag] and [Ag'] are not the true antigen concentrations but are the measurement of antigen density on the plate. The affinity constant K(aff) was calculated by using the formula K(aff) = (n - 1)/2(n[Ab'] - [Ab]), derived from law of mass action, where n = [Ag]/[Ag']. A computer program to calculate the affinity of antibody to the antigen using method described in this manuscript has been developed and discussed.

Antibodies, Monoclonal↗
PubMed1992

Calculation of antibody and antigen concentrations from ELISA data using a graphical method.

A graphical method for determining the concentration of either the antibody or the antigen from ELISA data is presented in the form of a GWBASIC program. In the program, ELISAEQ, optical densities (OD) obtained from a 96-well ELISA plate can be input either directly by interfacing a microplate reader to the computer or manually. The program uses standard sample data, and selects the semilogarithmic linear range. Over this range, a least-squares method is used to determine the concentrations of interest. In addition, a hyperbolic interpolation formula is derived over the entire range for estimating the antibody or antigen concentration of the unknown samples whose OD is beyond the linear range.

Antibodies↗
PubMedDate not supplied

Use of liposomes as an immunopotentiating delivery system: in perspective of vaccine development.

Liposomes have been widely used to deliver antigens to the antigen-presenting cells (APCs) and also to modify their immunological behaviour in model animals. We recently demonstrated the potential of yeast lipid liposomes to undergo membrane-membrane fusion with cytoplasmic membrane of the target cells. Interestingly, studies in the present report revealed that antigen encapsulated in yeast lipid liposomes could be successfully delivered simultaneously into the cytosolic as well as endosomal processing pathways of APCs, leading to the generation of both CD4+ T helper and CD8+ cytotoxic T cells. In contrast, encapsulation of same antigen in egg phosphatidyl-choline (PC) liposomes, just like its free form, has inefficient access to the cytosolic pathway of major histocompatibility complex (MHC) I dependent antigen presentation and failed to generate antigen specific CD8+ cytotoxic T-cell response. However, both egg PC as well as yeast lipid liposomes have elicited strong antigen specific antibody responses in immunized animals. These results imply usage of liposome encapsulated antigen as potential candidate vaccine capable of eliciting both cell mediated as well as humoral immune responses.

Animals↗
PubMedDate not supplied

Measurement and computation of murine interleukin-4 and interferon-gamma by exploiting the unique abilities of these lymphokines to induce the secretion of IgG1 and IgG2a.

A specific and new method for measuring Interleukin-4 and Interferon-gamma, based on the estimation of IgG1 and IgG2a isotypes secretion from B cells is described. An antagonizing effect of Interferon-gamma in the production of IgG1 induced by Interleukin-4 was neutralized by using antibody to Interferon-gamma. Similarly, the interference of Interleukin-4 in the Interferon-gamma mediated enhancement of IgG2a production was blocked by anti-Interleukin-4 antibody. The high concentrations of Interleukin-4 and Interferon gamma inhibited the secretion of IgG1 and IgG2a respectively. Therefore, in the assay described, the samples containing the cytokines were so diluted that their activity fell into the non-inhibitory zone. A computer program has also been developed for determining the concentrations of lymphokines.

Animals↗
PubMedDate not supplied

Group specific component (Gc) in erythema nodosum leprosum (ENL).

The distribution of phenotypes of group specific component (Gc) was examined in 71 lepromatous leprosy (LL) patients without any history of ENL reaction and 65 LL patients with history of frequent episodes of ENL reaction. The distribution of none of the phenotypes of Gc (Gc 1-1, Gc 2-1, Gc 2-2) was statistically significant among these groups.

Erythema Nodosum↗