PubMed Health⌕ Search

Biomedical subjects

K K Sethi

Publications and source records attributed to K K Sethi.

At least 73 records · Page 4Linked to original sources
PubMed1980

Hybridomas secreting monoclonal antibody with specificity for Toxoplasma gondii.

This study reports the successful establishment of eight functional hybridomas between mouse myeloma cells and spleen cells from mice hyperimmune to T. gondii as monitored by indirect immunofluorescence and radioimmunoassay techniques. Two of these eight cloned hybridomas showed positive reactivity in the Sabin Feldman dye test. Three hybridoma clones selected, following fusion of myeloma cells with freshly harvested spleen cells from hyperimmune mice, secreted into the culture medium antitoxoplasma antibody fo the IgC class. When spleen cells from hyperimmune mice were precultured in vitro for 5 days in presence of Con A and LPS and then fused with myeloma cells, five of the stable hybridomas secreted antitoxoplasma antibody of the IgM class, while one secreted antibody of the IgG class. These monoclonal antitoxoplasma antibodies should permit a rational approach to the purification of corresponding antigenic molecules from toxoplasma.

Animals↗
PubMed1979

Presence of viruses in a strain of mycoplasma pulmonis.

Filtrates prepared from heavily grown agar cultures of M. pulmonis strain Negroni-52 formed plaques on lawns of A. laidlawii strain JAl but not on those of M. pulmonis strains Ash or Negroni-52. The plaque-forming agent proved to be rod-shaped particles morphologically identical with mycoplasmavirus group 1. Evidence supporting the conclusion that the virus originated from Negroni-52 has been obtained. Electron microscopy revelaed that Negroni-52 is also a carrier of long-tailed phage-like particles.

Microscopy, Electron↗
PubMed1979

Induction of virus specific and H-2 restricted cytotoxic T cells by UV inactivated murine cytomegalovirus.

Infection of C3H mice with live or UV-inactivated murine cytomegalovirus (MCMV) was able to generate population(s) of lymphocytes in the spleen (CTL) which could exert a lytic effect against L cells infected with MCMV but not against uninfected or those infected with HSV-1. The effector cells proved to be theta-bearing T cells and the lysis of target cells was H-2 restricted. Data presented show that early viral protein synthesis but not viral DNA synthesis was necessary for the appearance of relevant antigenic determinant(s) on target cells. The results of co-capping experiments suggest that H-2 molecules may have close association with MCMV induced product(s) as also with murine leukemia virus glycoprotein (gp70) which is carried by normal L cells. Despite this observation, anti-H-2 serum effectively blocked the cytolysis whereas anti-gp70 and anti-MCMV sera failed. Anti-MCMV serum was effective in blocking cytolysis, only if the L cells were infected for 24 hours and then used as targets. MCMV infected L cells which were coated externally with inactivated Sendai virus could be effectively recognised by MCMV as also by sendai specific CTL. That the cytotoxicity exerted on such targets was of specific nature was revealed by the results of competitive blocking experiments with unlabelled targets.

Animals↗
PubMed1979

Maintenance of Fc receptors in hybrid cell lines obtained by fusing mouse splenic macrophages with mouse myeloma cells.

Mouse splenic macrophages were fused with cells of the mouse myeloma line P3-X63-Ag8 in the presence of inactivated Sendai virus. Two continuously growing hybrid cell lines were established from fusion mixtures. These hybrid cell lines exhibited macrophage-like morphology and continued to express macrophage derived Fc receptor activity even after prolonged culture in vitro.

Animals↗
PubMed1978

Intracellular behaviour of Leishmania enriettii within murine macrophages.

Both promastigotes and amastigotes of Leishmania enriettii were readily ingested by mouse peritoneal macrophages (MPM). Promastigotes after their entry within MPM were rapidly immobilized and their multiplication was never observed. Microscopic examination revealed that ingested promastigotes were degraded with MPM. Nonmotile amastigotes of L. enriettii taken up by MPM, on the other hand, multiplied intracellularly and eventually destroyed the infected cells.

Animals↗
PubMed1977

Specifically immune mouse T-cells can destroy H-2 compatible murine target cells infected with herpes simplex virus types 1 or 2.

Lymphocytes from the spleen (SL) or peritoneal cavities (PL) of HSV-1- or HSV-2-immunized C 3 H mice expressed pronounced cytotoxicity, as measured by 51Cr release assay, against L cells experimentally infected with HSF-types 1 or 2 but not against uninfected L cells. HSV-1 or HSV-2 immune lymphocytes induced substantially more 51Cr release when L-cell targets were infected with homotypic virus compared to those infected with heterotypic virus. Inasmuch as the cytotoxicity of specifically immune C 3 H SL for HSV-infected L cells was selectively eliminated by treatment with AKR anti-theta C 3 H serum plus complement, the effector cells in present system were theta-bearing T cells. Evidence has been provided which indicates that specifically immune T cells express cytotoxicity exclusively directed against different HSV-infected target cells (mouse embryo cells or mouse peritoneal macrophages) which share H-2 antigens with the effector cells.

Animals↗
PubMed1977

Search for the presence of lectin-binding sites on Toxoplasma gondii.

Evidence for the presence of carbohydrate on the surface membrane of Toxoplasma gondii trophozoites and on the cell wall of toxoplasma brain cysts was sought by fluorescent lectin staining. Using FITC-conjugated preparations of Concanavalin A (Con A), wheat germ agglutinin (WGA), or soy bean agglutinin (SBA), we have failed to obtain evidence for the binding of these lectins on the surface of T. gondii trophozoites. In contrast, the three test lectins bound effectively and specifically to the wall of toxoplasma brain cysts. Prefixation of cysts with glutaraldehyde or brief trypsinization of cysts did not affect the intensity of cyst wall fluorescence when stained with FITC-conjugated Con A, SBA, or WGA. The results are interpreted to indicate that whereas exposed Con A, SBA, and WGA binding sites are associated with the wall of toxoplasma brain cysts, such lectin-binding saccharide residues are not present on the surface of trophozoites in exposed or reactive form.

Animals↗
PubMed1976

Appearance of IgG (Fc) receptor(s) on cultured human fibroblasts infected with human cytomegalovirus.

Cultured human diploid fibroblasts (WI-38) after infection with human cytomegalovirus (CMV) but not when uninfected, could hemadsorb sheep red blood cells (SRBC) coated with rabbit anti-SRBC IgG. The adsorption of IgG-coated SRBC to virus-infected cells was completely abolished if the tests were carried out in the simultaneous presence of rabbit antiserum elicited against CMV. Normal sera of rabbit or human origin as well as purified human IgG but not Fab fragment of human IgG could also abolish the binding of sensitized SRBC to CMV-infected fibroblasts. Active metabolism on the part of CMV-infected fibroblasts proved to be an important requisite for demonstrating binding of sensitized SRBC to their surfaces. By using an indicator Staphylococcus aureus to which rabbit antiserum against normal human IgG, IgM, or IgA was bound via Fc fragments, evidence has been obtained which suggests the existence of receptor(s) on CMV-infected WI-38 cells that react specifically with Fc region of human IgG.

Animals↗
PubMed1975

Cytotoxicity mediated by soluble macrophage product(s).

The soluble macrophage product(s) released by nonimmune mouse peritoneal macrophages exposed to endotoxin or from listeria-immune macrophages after incubation with specific antigen mediated cytotoxic activity against malignant cell types and, to a lesser extent, against normal cells. Only undiluted supernatants from nonimmune or listeria-immune macrophages cultured with medium 199 alone exerted some degree of cytotoxicity on the different target cell types tested. The macrophage product(s) retained cytotoxic activity storage at minus 20 degrees C, was stable when heated at 56 degrees C for 30 minutes, but was completely inactivated when exposed at 100 degrees C for 5 minutes. In the presence of 15 mug exogenous lysozyme/ml, the cytotoxic activity of the macrophage product(s) was significantly enhanced.

Animals↗
PubMed1975

Immunity to Toxoplasma gondii induced in vitro in non-immune mouse macrophages with specifically immune lymphocytes.

Male and female CBA mice were used to study in vitro the mechanisms involved in the development and expression of cellular immunity to toxoplasma infection. The lag phase preceding toxoplasma division was delayed in nonimmune macrophages obtained from peritoneal cavities stimulated with thioglycollate. Specific anti-toxoplasma activity was conferred on nonimmune macrophages incubated with toxoplasma-immune spleen lymphocytes and soluble toxoplasma antigen. Treatment of immune spleen cell populations with anti-theta serum plus complement abolished completely their activity of conferring anti-toxoplasma activity on nonimmune macrophages, demonstrating that the essential cells were T lymphocytes. The mediator(s) responsible for the acquisition of immunity to toxoplasma in the nonimmune macrophages were soluble. Heat-inactivated, toxoplasm-immune macrophages of fibroblasts. The findings are related to previous investigations of induced immunity in animals and man.

Animals↗