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Biomedical subjects

S R Watson

Publications and source records attributed to S R Watson.

At least 55 records · Page 3Linked to original sources
PubMed1991

Neutrophil influx into an inflammatory site inhibited by a soluble homing receptor-IgG chimaera.

Neutrophil-mediated inflammation is involved in a number of human clinical manifestations, including the adult respiratory distress syndrome, multi-organ failure and reperfusion injury. One way of inhibiting this type of inflammatory response would be to block competitively the adhesive interactions between neutrophils and the endothelium adjacent to the inflamed region. The lectin-containing murine adhesion molecule gp90MEL, the homing receptor, is found on all leukocytic cells, including neutrophils. MEL 14, a monoclonal antibody directed against this adhesion molecule, blocks lymphocyte traffic to lymph nodes and extravasation of neutrophils from blood to inflammatory sites. Here we show that administration to mice of a soluble immunoglobulin chimaera containing the murine homing receptor extracellular domain significantly decreases the number of neutrophils that migrate to the peritoneum in response to the inflammatory irritant thioglycollate. These results indicate that soluble forms of a single type of adhesion molecule, the homing receptor, could be clinically effective compounds for the inhibition of neutrophil-mediated inflammation.

Animals↗
PubMed1991

The complement binding-like domains of the murine homing receptor facilitate lectin activity.

The leukocyte homing receptor (HR), the endothelial leukocyte adhesion molecule, and gmp140/platelet activation-dependent granule membrane protein are members of a family of adhesion molecules, termed the lectin cell adhesion molecules (LEC-CAMS) which are unified by a multi-domain structure containing a lectin motif, an epidermal growth factor-like (egf) motif, and variable numbers of a complement binding-like (CB) motif. Previous data have indicated a predominant role for the lectin motif in cell adhesion directed by the LEC-CAMS, although the egf-like domain of the HR may also play a potential role in cell binding. While the role(s) of the CB domains in the LEC-CAMS is currently not understood, they have been hypothesized to act as rigid spacers or stalks for lectin and perhaps, egf domain presentation. In this paper, we analyze the functional characteristics of murine HR-IgG chimeras containing the lectin, lectin plus egf, and lectin plus egf plus CB domains. The Mel 14 mAb, an adhesion blocking antibody which recognizes a conformational determinant in the N-terminus of the HR lectin domain, shows a significantly decreased affinity for a HR construct which lacks the CB motifs, consistent with the possibility that the CB domains are involved with lectin domain structure. In agreement with this conjecture, HR mutants lacking the CB domains show a profound decrease in lectin-specific interaction with the carbohydrate polyphosphomannan ester, suggesting that the changes in Mel 14 affinity for the lectin domain are reflected in lectin functionality. Various assays investigating the interactions between the HR deletion mutants and the peripheral lymph node high endothelium, including cell blocking, immunohistochemical staining, and radioactively labeled ligand binding, all showed that removal of the CB domains results in a lack of HR adhesive function. These results imply that the CB domains of the HR, and, by analogy, the other members of the LEC-CAM family, may play important structural roles involving induction of lectin domain conformation and resultant functionality.

Antibodies, Monoclonal↗
PubMed1990

A homing receptor-IgG chimera as a probe for adhesive ligands of lymph node high endothelial venules.

The binding of lymphocytes to high endothelial venules (HEV) within peripheral lymph nodes (pln) is thought to be mediated by a lectinlike adhesion molecule termed the pln homing receptor (pln HR). The cloning and sequencing of cDNAs encoding both murine and human pln HR revealed that these adhesion molecules contain protein motifs that are homologous to C-type or calcium dependent lectin domains as well as to epidermal growth factor (egf) and complement-regulatory protein domains. We have produced a novel, antibody-like form of the murine HR by joining the extracellular region of the receptor to a human IgG heavy chain. This antibody-like molecule is capable of recognizing carbohydrates, blocking the binding of lymphocytes to pln HEV, and serving as a histochemical reagent for the staining of pln HEV. This murine HR-IgG chimera should prove useful in analyzing the distribution of the HR ligand(s) in normal as well as in inflammatory states.

Animals↗
PubMed1990

The extracellular domain of HER2/neu is a potential immunogen for active specific immunotherapy of breast cancer.

The proto-oncogene HER2/neu encodes a protein tyrosine kinase (p185HER2) that is homologous to the human epidermal growth factor receptor. Amplification and/or overexpression of HER2/neu occurs in multiple human malignancies and appears to be integrally involved in progression of some breast and ovarian cancers. Because of this fact, HER2/neu is an intriguing target for specific cancer therapeutic strategies. One such strategy is active specific immunotherapy, in which the immune system is targeted at specific antigens expressed by tumor cells. We have employed a transfected cell line that secretes the extracellular domain of p185HER2 as a source of HER2-derived immunogen in a guinea pig model. The immunized animals developed a cellular immune response, as monitored by delayed-type hypersensitivity, and antisera derived from immunized animals specifically inhibited the in vitro growth of human breast tumor cells overexpressing p185HER2. These data provide support for an immunotherapeutic approach to cancers characterized by overexpression of the HER2/neu proto-oncogene.

Animals↗
PubMed1987

Plasma lipoproteins and transferrin regulate the proliferation of a continuous T lymphocyte cell line.

Lipoproteins of hydrated densities less than 1.063 g/ml, very low density (VLDL) and low density (LDL) lipoproteins, could both enhance and suppress the proliferation of T lymphocyte cell lines. Enhancement and suppression were dependent on lipoprotein and transferrin concentrations. Enhancement occurred at low lipoprotein and high transferrin; suppression, at high lipoprotein and low transferrin. Lipoprotein suppression required a constituent of cell-conditioned medium as evidenced by the fact that lipoproteins did not suppress the replicative response of the IL-2-dependent murine cell line CTLL-2 to purified IL-2 but could suppress the response to cell-conditioned medium IL-2. For lipoprotein suppression and its relief by transferrin, both growth-regulating factors were required early in the cell cycle, suggesting that events important to progression through G1 are influenced. The data establish that the interplay between plasma lipoproteins, transferrin, and an unknown constituent of cell-conditioned medium can regulate the proliferation of T lymphocytes.

Animals↗
PubMed1986

Expression of human T antigens in interspecies hybridomas.

Interspecies hybrids were constructed by fusing normal human male peripheral blood mononuclear cells with BW5147, a HGPRT- thymoma derived from an AKR mouse. Hybrid cells were selected in HAT media in culture dishes containing 1 X 10(7) human red blood cells. Twelve weeks after fusion, hybridomas were diluted to 10-15 cells/well and characterized for their expression of the human immune cell surface antigens HLA-DR, T3, T4, and T8 using fluorescent microscopy and cytographic analysis. More than 70% of the hybrid colonies expressed human T-cell surface antigens. Moreover the specific human repetitive DNA (ALU) bound to DNA sequences isolated from the hybridomas after Southern transfers. However, the same hybrids did not have a statistically significant increase in their chromosome number when compared to the mouse parent cell line. Several of the hybridomas produced a soluble factor capable of stimulating the growth of the IL-2 restricted murine cell line CTLL-2 and supported DNA synthesis in human peripheral T-cell populations. Panning experiments demonstrated that the IL-2 producing hybridomas could be enriched by selecting for the human T-cell surface antigen T3. The results presented here indicate that mouse X human hybridomas which express a broad range of human lymphocyte markers can be constructed and maintained in continuous culture for extended periods of time. It also appears that the T3-Ti receptor complex mediates the proliferation of T cells through the T3 molecules linkage to the secretion and/or production of IL-2. The usefulness of interspecific T-cell hybrids as an immunogenetic research tool as well as the significance of the mapping data are discussed.

Animals↗
PubMed1985

Immunoregulation in disseminated murine histoplasmosis: disturbances in the production of interleukins 1 and 2.

Production of IL 1 and IL 2 by splenocytes from C57BL/6 mice was measured at wk 1, 3, 8, and 14 after i.v. inoculation with 6 X 10(5) Histoplasma capsulatum (Hc) yeasts. As compared with age-matched controls, IL 1 production by splenocytes from Hc-infected mice was reduced severely at wk 1 and 3 of infection, greater than normal at wk 8, and within normal range at wk 14. IL 2 production was also reduced at wk 1 and 3 of infection; it was normal at wk 8 and was elevated at wk 14. Indomethacin and catalase failed to restore IL 1 production by splenocytes from infected mice, and exogenous IL 1 did not augment IL 2 production by these cells. A factor capable of suppressing the activity of IL 2 was detected in supernatants of concanavalin A-stimulated splenocytes from infected animals at wk 1 and 3 of infection, respectively. No factor capable of suppressing IL 1 activity was detected. Thus, the deficits of cell-mediated immunity in mice with systemic Hc infection may derive, in part, from impaired amplification of the immune response consequent to abnormal generation of IL 1 and IL 2.

Animals↗
PubMed1984

Flow microfluorometry analysis of alterations in T-lymphocyte subsets during murine listeriosis.

C57BL/6 mice were infected intravenously with 6 X 10(3) Listeria monocytogenes organisms. As early as day 3 of infection, there was a marked reduction in the number of lymphocytes recovered from the peripheral blood, bone marrow, and thymuses of infected animals. Concomitantly, there was an increase in the number of splenic lymphocytes. By day 14, both the total and differential cell counts were similar in both infected and normal animals. Flow microfluorometric studies comparing the Thy-1.2, Lyt-1, Lyt-2, and surface immunoglobulin (SIg) phenotypes of lymphocytes from normal and infected mice were performed. Between days 3 and 5, there was a decrease in the percentage of Thy-1.2+ cells in the spleens of L. monocytogenes-infected animals. Conversely, the percentages of Lyt-1+, Lyt-2+, and SIg+ cells remained constant. At day 7 of infection, the percentage of Thy-1.2+ splenocytes was within normal limits, and at day 10, the percentage of Thy-1.2+ cells was elevated slightly. The absolute numbers of Thy-1.2+ cells were comparable in both infected and normal animals at early stages (days 3 to 5) of L. monocytogenes infection, but there was a marked elevation of Thy-1.2+ splenocytes at days 7 to 14 of infection. Lyt-1+, Lyt-2+, and SIg+ splenocytes increased in absolute numbers as early as day 3 of infection and were still elevated at day 14. Adrenalectomy before infection had no effect on the results obtained, suggesting that these changes were not mediated by endogenous steroids.

Adrenalectomy↗
PubMed1984

Cellular origins and target cells of immunoregulatory factors in mice with disseminated histoplasmosis.

Disseminated infection with Histoplasma capsulatum stimulates the production of a suppressor factor (SF-H) by spleen cells from C3H/HeJ mice and a helper factor (HF-H) by spleen cells from C57BL/6 mice. In the present study these disparate immunoregulatory factors were analyzed in detail with regard to: a) the surface phenotype of the cells that produce SF-H and HF-H; b) the role of accessory cells in the production of these factors; and c) the surface phenotype of the target cells activated by SF-H and HF-H. Treatment of spleen cells from Histoplasma-infected C3H/HeJ mice with anti-Thy-1.2 plus complement (C) or with anti-Ly-2 plus C or with anti-I-Jk antiserum plus C abolished production of SF-H. Conversely, generation of HF-H by spleen cells from C57BL/6 mice was abrogated by treatment with either anti-Thy-1.2 plus C or with anti-Ly-1 plus C. Thus, a Thy-1.2+, Ly-2+, I-J+ T cell releases SF-H, and a Thy-1.2+, Ly-1+ T cell secretes HF-H. Production of SF-H and HF-H by splenic T cells was reduced markedly by depletion of macrophages (M phi); readdition of 1% syngeneic, plastic-adherent splenocytes from normal or infected mice to M phi-depleted, splenic T cell cultures of either strain restored the capacity to generate immunoregulatory factors. Furthermore, adherent splenocytes from normal or infected mice liberated a factor or factors that enhanced production of both SF-H and HF-H. Kinetic studies demonstrated that activation of normal spleen cells required at least 48 hr of exposure to SF-H or HF-H. Both factors failed to activate splenocytes pretreated with anti-Thy-1.2 plus C. Spleen cells from C3H/HeJ mice depleted of Ly-1+, Ly-2+, or I-J+ cells and exposed to SF-H did not demonstrate suppressor activity, whereas Ly-1-depleted splenocytes from C57BL/6 mice exposed to HF-H failed to exert helper activity. Therefore, the target of SF-H is a Thy-1.2+, Ly-1+2+, I-J+ T cell, and the target of HF-H is a Thy-1.2+, Ly-1+ T cell.

Animals↗
PubMed1983

Age-related loss of Lyt-1,2 cells in C58 mice results in susceptibility to lactic dehydrogenase virus-induced polioencephalomyelitis.

C58 mice (aged greater than or equal to 5 months) are susceptible to age-dependent polioencephalomyelitis, a paralytic central nervous system disease induced by lactic dehydrogenase virus. Susceptibility results from the loss of protective T cells. Data are presented showing a positive correlation between the age-related loss of Lyt-1,2 cells and the development of susceptibility to neuroparalytic lactic dehydrogenase virus infection.

Aging↗
PubMed1983

Immunoregulation in experimental disseminated histoplasmosis: flow microfluorometry (FMF) studies of the Thy and Lyt phenotypes of T lymphocytes from infected mice.

Previous studies have shown that mice infected i.v. with 6 X 10(5) yeast phase Histoplasma capsulatum (Hc) develop suppressed immune responses during weeks 1 to 4 of infection but that by weeks 8 to 12 of infection these responses return to normal. In this study total and differential cell counts showed that as early as the third day of infection there was a marked reduction in the number of lymphocytes recovered from the peripheral blood, bone marrow, and thymus of infected animals. Concomitantly, there was an increase in the number of splenic lymphocytes. By day 28 both the total and differential cell counts were similar in both infected and normal animals. Flow microfluorometric (FMF) studies comparing the Thy-1.2, Lyt-1, Lyt-2, and surface immunoglobulin (slg) phenotypes of lymphocytes from normal and infected mice were performed. Between days 5 and 7 the thymocytes from infected mice displayed a higher relative fluorescence intensity (RFI) of the Thy-1.2 marker than normal thymocytes, whereas at day 10, the RFI was less than that of normal thymic lymphocytes. Between days 7 and 10 of infection the RFI of the Lyt-2 marker was less on thymocytes from Hc-infected mice; however, there was no change in the Lyt-1 marker. Examination of these lymphocyte markers in blood, spleen, and mesenteric lymph nodes showed that there were decreases in the RFI of both the Thy-1.2 and Lyt-2 between days 5 and 10 of infection. No changes were observed in the Lyt-1 or slg markers. By day 28 there were no differences between the normal and infected mice with respect to any surface marker in any of the organs studied. In other experiments, the effect of adrenalectomy before infection on these surface markers was studied. Absolute numbers of Thy-1.2+, Lyt-1+, and Lyt-2+ cells were significantly increased in the spleen and significantly decreased in the thymus and peripheral blood of infected mice relative to normal controls. These studies suggest that there is a migration of cells from the thymus, blood, and bone marrow to the spleens of mice with disseminated Hc infection.

Adrenalectomy↗
PubMed1983

Fernandez and Mitsuda reactivity in guinea pigs sensitized with heat-killed Mycobacterium leprae: persistence and specificity of skin reactivity to soluble and particulate antigens.

Guinea pigs were sensitized with 500 micrograms dry weight of heat-killed Mycobacterium leprae, M. tuberculosis H37Rv, M. vaccae, or M. nonchromogenicum suspended in saline. Significant Fernandez (peak swelling at 48 hr) and Mitsuda (peaking at 21 days) reactions were observed when all four groups of animals were skin tested with 10 micrograms of the homologous whole-cell antigen (WCA) preparations one month after sensitization. Some of the guinea pigs were given a booster injection of the homologous suspension three months later and were then retested with the four WCA preparations. The Fernandez (rather than the Mitsuda) reactivity was enhanced by the second immunization and was still substantial when tested eight months after boosting. The Mitsuda-type responses observed 12 months after the primary sensitization peaked earlier than in the first- and four-month tests, regardless of the vaccinating organism. The M. leprae-sensitized guinea pigs produced larger Fernandez skin reactions than those seen in the other three groups of sensitized animals, but there was substantial crossreactivity between M. leprae and M. tuberculosis antigens, as well as somewhat lesser responsiveness in the M. vaccae- or M. nonchromogenicum-sensitized animals skin tested with lepromin. The present study indicates that saline suspensions of heat-killed M. leprae induced a highly persistent state of lepromin hypersensitivity which was quantitatively superior to that observed in animals sensitized with the three other mycobacteria.

Animals↗
PubMed1982

Immunoregulation in disseminated histoplasmosis: characterization of the surface phenotype of splenic suppressor T lymphocytes.

C57BL/6 and C3H/HeJ mice were infected intravenously with 6 X 10(5) yeast-phase Histoplasma capsulatum organisms. After 1 week, splenocytes from both mouse strains showed diminished antibody responses to sheep erythrocytes in vitro; these cells also were able to suppress the response of normal syngeneic cells. Passage of splenocytes from infected mice through a nylon wool column yielded a population enriched for T cells that exerted suppressor activity, although to a smaller extent than did unfractionated cells. Treatment of the T-cell-enriched population from both strains of mice with either anti-Thy 1.2 or anti-Ly 2 and complement resulted in a loss of this immunosuppressive ability. In addition, anti-I-Jk antiserum was effective in ablating the suppressive effect of C3H/HeJ nylon wool-passed spleen cells. The conclusion drawn from these experiments is that the T cells from H. capsulatum-infected animals which are capable of modulating the in vitro plaque-forming cell response to sheep erythrocytes bear Ly 2 and I-J determinants on their surfaces.

Animals↗
PubMed1981

The specificity of suppressor T cells induced by chronic Mycobacterium avium infection in mice.

Normal mice infected intravenously with 10(6) or 10(8) viable M. avium develop persistent infections of the lungs, liver and spleen. The liver and spleen counts remained relatively constant whereas those for the lung slowly increased until eventually some of the animals began to die as a result of the infection. None of the heavily infected mice developed delayed hypersensitivity (DTH) to the M. avium cytoplasmic protein antigen (CPA). Spleen cells harvested at increasing time periods after the M. avium infection were tested for their blastogenic responsiveness to PHA and M. avium CPA. The presence of suppressor T cells within the heavily infected spleens was demonstrated by means of cell-mixing experiments before and after treatment of the anergic spleen cells with anti-Thy-1.2 antiserum and complement. The specificity of the suppressor T cells was measured in terms of their ability to depress responsiveness to sheep erythrocytes and an allograft challenge. Initially, the suppressor T cell population affected all of the T cell-mediated responses but as the infection progressed, so the non-specific host responses tended to return gradually towards normal, whereas the specific M. avium CPA-mediated suppression persisted largely unchanged.

Animals↗
PubMed1981

The effect of combined chemotherapy on suppressor T-cell activity in Mycobacterium simiae-infected mice.

Specific pathogen-free B6D2 mice were infected with 10(6) or 10(8) viable Mycobacterium bovis (BCG Pasteur) or Mycobacterium simiae and the in vivo growth curves were correlated with the levels of delayed hypersensitivity developed against a cytoplasmic protein antigen (CPA) injected into a hind footpad at increasing time intervals after infection. Half of the heavily infected, anergic mice were placed on a regimen of 10 mg of rifampin, 5 mg of amikacin and 2 mg of clofazimine per 100 ml of drinking water 2 or 8 weeks into the infection. The number of viable mycobacteria recovered from the lungs and spleens of the treated mice (compared with the corresponding drug-free controls) were reduced by up to 10,000-fold over a 3-month treatment period. Spleen cells were harvested at increasing time intervals from the drug-treated and control mice and T-cell enriched suspensions were tested for blastogenic responsiveness to phytohaemagglutinin (PHA) and to the specific CPA mitogen. The early (day 14) peak in tritiated thymidine ([3H]-TdR) uptake was followed by a sharp drop to near background levels. Cell-mixing experiments demonstrated the presence of a suppressor T-cell population in the heavily infected spleens of the M. simiae-infected mice. The suppressor-cell effect was substantially reduced following combined drug therapy although the specific CPA-mediated response was less affected than the non-specific PHA-mediated response.

Amikacin↗
PubMed1980

Microscopic counts carried out on Mycobacterium leprae and M. tuberculosis suspensions. A comparison of three staining procedures.

Standard smears of heat-killed Mycobacterium leprae and M. tuberculosis H37Rv were counted microscopically following staining by the Ziehl-Neelsen, auramine, and silver-methenamine methods. The numbers of stained bacillary bodies were consistently higher in the silver-methenamine stained smears compared to the Ziehl-Neelsen and auramine stained smears. The auramine smears were examined under ultraviolet illumination and permitted the enumeration of the brightly fluorescent bacilli against a black background. The auramine counts were not as high as those obtained using the silver-methenamine stained preparations but were consistently higher than those obtained with the Ziehl-Neelsen preparations. Both the auramine and silver-methenamine stained preparations clearly outlined the cell walls of the bacilli in the smears and this greatly facilitated the counting process, especially if the cell suspension was badly clumped.

Mycobacterium leprae↗