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Biomedical subjects

M D Gorrell

Publications and source records attributed to M D Gorrell.

33 records · Page 2Linked to original sources
PubMed1992

Tumour necrosis factor and interleukin 6 production during interaction between activated CD4+ lymphocytes and simian immunodeficiency virus-infected macrophages.

The mechanism for the gradual loss of CD4+ T lymphocytes and the development of the slowly progressive inflammatory/degenerative lesions that accompany human immunodeficiency virus infection are poorly understood. Using the Simian immunodeficiency virus (SIVmac) macaque model of AIDS, we found that persistently infected primary macrophages fuse with primary activated CD4+ lymphocytes and that this interaction results in production of tumour necrosis factor-alpha (TNF alpha) and interleukin 6 (IL-6). An earlier report had shown that SIV-infected macaque macrophages fuse with CEM174 cells (a human CD4+ cell line) and cause their lysis. In the present report, we have shown that TNF-alpha and IL-6 are also produced during the early stages of this interaction. Data from cocultivation of infected macrophages with several CD4+ T cell lines, including CEM174, suggested that the cytokines are produced by the T cells, and that cytokine production is restricted to those cells which not only express CD4, but are also capable of fusing with the infected macrophages. These data suggest that infected macrophages in vivo could fuse with and eliminate activated CD4+ lymphocytes and, during this interaction, release cytokines, which would contribute to the degenerative and inflammatory lesions characteristic of this disease.

Animals↗
PubMed1992

Ovine lentivirus is macrophagetropic and does not replicate productively in T lymphocytes.

The lentiviruses of sheep, goats, and horses cause chronic multiorgan disease in which macrophages are highly permissive for viral replication. Monocytes, which mature into macrophages, are thought to be latently infected with lentivirus, but the extent to which other leukocytes are infected is unknown. Dendritic cells have not been studied separately from monocytes and T-cell subsets have not been examined in previous attempts to identify infected cells in peripheral blood mononuclear cells (PBMC). We found no evidence of T-cell tropism using an animal-passaged, pathogenic ovine lentivirus. Phytohemagglutinin-stimulated infectious PBMC produced 20-fold less virus than differentiated macrophages, and cocultivation of infectious PBMC with fresh, uninfected phytohemagglutinin blasts did not facilitate virus replication. Furthermore, central lymph cells, the best in vivo source of purified lymphocytes, lacked virus and did not yield virus upon in vitro cultivation. In contrast, cultivated blood-derived macrophages were highly permissive for viral replication. To identify the latently infected PBMC, PBMC from infected sheep were selectively depleted of monocytes and B cells by passage over nylon wool and then of nonadherent cells bearing CD4, CD8, T19, gamma delta T-cell receptor, CD45RA, or major histocompatibility complex class II antigens by panning. Removal of adherent monocytes and B cells or of adherent cells and the three major T-cell subsets (CD4+, CD8+, T19+) did not decrease the infectivity of PBMC. The richest sources of infected cells in fresh PBMC were CD45RA+ and major histocompatibility complex class II+ nonadherent cells, which are three characteristics of dendritic cells. Thus, the dendritic cell, and not the monocyte or the CD4+ cell, is probably the predominant infected cell type in blood.

Animals↗
PubMed1991

Expression of the rat CD26 antigen (dipeptidyl peptidase IV) on subpopulations of rat lymphocytes.

The T cell activation antigen CD26 has been recently identified as the cell surface ectopeptidase dipeptidyl peptidase IV (DPP-IV). DPP-IV is found on many cell types, including lymphocytes, epithelial cells, and certain endothelial cells. The MRC OX61 monoclonal antibody (MAb) which specifically recognises rat DPP-IV was used to examine the expression of CD26/DPP-IV on rat lymphocytes. The molecular nature of the antigen was examined by immunoprecipitation from thymocytes, splenocytes, and hepatocytes. Analysis by one- and two-dimensional gel electrophoresis indicated that the native form of CD26 includes a 220-kDa homodimer. On tissue sections MRC OX61 MAb stained nearly all thymocytes and in the spleen and lymph nodes predominantly stained the T cell areas. However, in immunofluorescence experiments OX61 stained 80 to 87% of lymph node cells and 78 to 85% of spleen cells. Furthermore, two-colour immunofluorescence analysis of the CD4+, CD8+, and Ig+ lymphocyte subsets indicated that only 2 to 5% of each of these subsets lacked OX61 staining. Spleen cells and thymocytes of both CD4+ and CD8+ subsets stained much more intensely with OX61 after these cells were stimulated with phytohemagglutinin. These findings indicate that rat CD26 antigen expression is not confined to the T cell population as has been suggested, but also occurs on B cells, and is increased on T cells following their activation.

Animals↗
PubMed1991

T and B lymphocyte subsets in spermatic granulomas in five rams.

Epididymal spermatic granulomas from five adult (greater than 4 years old) rams from a commercial flock were evaluated by quantitative histologic methods. Sections were stained for isotype specific immunoglobulin (Ig)-containing cells or specific lymphocyte subsets, as indicated by plasma membrane staining with monoclonal antibodies (MoAb). For the purpose of analysis, individual spermatic granulomas were allocated to one of three groups (early, resolving, or intermediate) on the basis of histologic examination. Ig-containing cells were most prevalent in early spermatic granulomas, and IgG-containing cells predominated in all spermatic granulomas regardless of their presumed age. IgM immunoglobulin-containing cells were the next in prevalence, and IgA-containing cells were infrequent. Assessment of lymphocyte subsets confirmed that lymphocytes present were of both T- and B-cell lineage and were well represented in all spermatic granulomas. CD4+ (MHC Class II-restricted "helper") T-cells were more prevalent in early spermatic granulomas than in intermediate or resolving types, while CD8+ (MHC Class I-restricted, "cytotoxic/suppressor") T-cells were more prevalent in spermatic granulomas of the intermediate type. These results suggest that in addition to an essentially foreign body reaction to extravasated spermatozoa, both local production of antibody and accumulation of a variety of B- and T-lymphocytes are present in ovine spermatic granulomas.

Animals↗
PubMed1990

Identification of the bile canalicular cell surface molecule GP110 as the ectopeptidase dipeptidyl peptidase IV: an analysis by tissue distribution, purification and N-terminal amino acid sequence.

This paper describes the tissue distribution, purification and N-terminal amino acid sequence of the bile canalicular cell surface molecule dipeptidyl peptidase IV. Immunoperoxidase staining of cryostat sections of rat liver with a monoclonal antibody, Medical Research Council OX-61, indicated specific binding to hepatocyte bile canalicular domains and brush borders of bile ducts. Additional staining was seen in other epithelial brush borders (small intestine, kidney, colon, pancreatic duct); acinar structures in salivary glands; endothelial structures and T cell areas in thymus, spleen and lymph node. The tissue distribution suggested that monoclonal antibody OX-61 binds to the ectoenzyme dipeptidyl peptidase IV. This was confirmed by depletion of dipeptidyl peptidase IV activity from tissue homogenates by monoclonal antibody OX-61 coupled to Sepharose. The molecule recognized by OX-61 was then purified from liver and kidney by monoclonal antibody affinity chromatography. The molecule had a molecular weight of 110 kD under reducing conditions. The purified molecule was subsequently analyzed for amino acid composition and N-terminal amino acid sequence. Thirty-one N-terminal amino acids were sequenced and indicated identity with part of the predicted N-terminus of the previously cloned bile canalicular molecule GP110. On review, other similarities between dipeptidyl peptidase IV and GP110 were detected: molecular weight, deglycosylated form and metabolic half-life. Finally, the recent cloning of dipeptidyl peptidase IV permitted a comparison between the molecule recognized by monoclonal antibody OX-61, GP110 and dipeptidyl peptidase IV. It is concluded that these three molecules are almost certainly identical.

Amino Acid Sequence↗
PubMed1990

Cysticercosis: cellular immune responses during primary and secondary infection.

Immune reactions to cysticercosis have been extensively studied in mice. The lack of significant lymphocyte infiltration into the livers of infected mice and the obvious role of antibodies in rejection has led to the general conclusion that cellular reactions do not play a role in protection against this disease. In contrast, the present study examining the immune response to cestode infections in a large animal model (sheep) revealed the presence of a massive and highly organized cellular infiltration in the livers after a secondary Taenia hydatigena infection. The majority of the infiltrating lymphocytes were of the CD4+ phenotype with much fewer CD8+ cells present. While most gamma delta-TCR+ cells in peripheral blood are SBU-T19+, the majority of gamma delta-TCR+ lymphocytes in the liver lesions are SBU-T19- suggesting selective migration of these cells into the lesions. In contrast to the diffuse distribution of T cells in the lesions, B cells were present as distinct aggregates. In primary T. hydatigena infections, host class I and class II MHC antigens were shown, for the first time in cestode infections, to be absorbed onto the surface of the metacestode bladderwall indicating their possible involvement in parasite survival. No immune reactions were observed close to the parasite although lymphocytes and eosinophils were infiltrating the adjacent portal tract areas. Most lymphocytes in both primary and secondary infections were positive for MHC class II antigens suggesting selective recruitment of activated cells to the site of infection. Significant changes in relative and absolute numbers of lymphocyte subpopulations were also observed in the draining hepatic lymph nodes dominated by a massive increase of B cells. In contrast, at the peak of local cellular infiltration, no changes in lymphocyte subpopulations were observed in peripheral blood showing the limited usefulness of this compartment in studying cellular changes in localized infections. The vigorous cellular response observed in the livers of sheep contrasts sharply with the lack of lymphocyte infiltration reported in mice indicating that small animal models may not be appropriate to study cellular responses to cysticercosis in large animals and man.

Animals↗
PubMed1989

Lymphocyte subpopulations of sheep in protective immunity to Taenia hydatigena.

Lymphocyte subpopulations entering the liver and surrounding the rejection sites during a 9-day period after infection of immune sheep with Taenia hydatigena were identified with the aid of monoclonal antibodies against lymphocyte cell surface markers. Viable lymphocytes were isolated from the liver tissue and stained by indirect immunofluorescence for subsequent flow cytometry analysis. Over the first 6 days after challenge infection a marked increase in the ratio of T-helper to T-suppressor/cytotoxic lymphocytes was observed. SBU-T19+ lymphocytes, a CD5+ T-cell subpopulation uniquely identified in the sheep, were present in small numbers in sheep liver both before and after infection. There was a large, continuous increase of sIg+ B-cells over the 9-day observation period after infection. Eosinophils were the predominant granulocytes in the liver of infected sheep. The exact location of the leucocyte subpopulations in respect to the rejection sites in infected liver was determined by in-situ immunoperoxidase staining of frozen liver sections. The evolution of the parasite-induced leucocyte response was characterized by the appearance of a central core of eosinophils surrounded by increasing numbers of CD4+ helper T-cells. CD8+ (suppressor/cytotoxic) and SBU-T19+ T-lymphocytes were present in much smaller numbers and by day 9 after infection were located predominantly around the periphery of the lesions. Distinct foci of tightly packed B-cells developed within the lesions and increased dramatically in size over the 9-day observation period. At this time, lesions appeared as compact aggregations of leucocytes encircled by a second band of eosinophils. Both T- and B-lymphocytes within the lesions stained positive for class II major histocompatibility antigens.

Animals↗
PubMed1989

Lymphocyte subpopulations in the blood of sheep persistently infected with border disease virus.

The surface phenotypes of peripheral blood lymphocytes in groups of lambs and adult sheep persistently infected with Border disease virus (P-I BD) were compared with those of healthy controls. The proportion and number of lymphocytes bearing surface immunoglobulin (sIg+) and expressing class II MHC antigen (B cells) were significantly increased. A significant increase in CD1+ lymphocytes was also evident. Conversely, the proportion of T lymphocytes in P-I BD lambs was reduced. A marked reduction in the proportion of circulating lymphocytes expressing class I MHC antigen was also observed. These findings were not affected by differences in the strain of the virus responsible for the persistent infection.

Aging↗
PubMed1988

Lymphocyte phenotypes in the abomasal mucosa of sheep infected with Haemonchus contortus.

Lymphocyte subpopulations in the abomasal mucosa of worm-free and parasitized sheep were assessed in situ. A preponderance of T-lymphocytes, with approximately equal numbers of cells expressing CD5, CD4 and CD8 antigens, was found. Most of the lymphocytes expressing CD8 lacked CD5. Using a panel of 15 monoclonal antibodies to ovine leucocyte antigens, abomasal lymphoid follicles in the mucosa were shown to resemble lymph node follicles phenotypically. Abomasal epithelial cells contained major histocompatibility complex (MHC) class II antigen. Infection or hyperimmunization of pasture-reared sheep with the gastric nematode Haemonchus contortus increased the numbers of mucosal mast cells and eosinophils but did not alter the phenotypic composition or number of mucosal lymphocytes or the pattern of expression of MHC class II antigens.

Abomasum↗
PubMed1988

Presence of a distinct CD8+ and CD5- leucocyte subpopulation in the sheep liver.

The relative proportions of CD5, CD4, CD8, SBU-T19 and surface immunoglobulin (sIg)-positive lymphocytes in normal sheep livers were determined by flow cytometry analysis of isolated liver leucocytes and compared to lymphocyte subpopulations found in peripheral blood and hepatic lymph nodes. In contrast to the blood, very low numbers of SBU-T19+ cells were found in both the liver and hepatic lymph nodes. The ratio of helper versus suppressor/cytotoxic T cells in the liver was less than 1, which was much lower than in blood or hepatic lymph nodes. A large proportion of liver lymphocytes were characterized by a low intensity staining for the CD8 antigen (CD8L). Two-colour flow cytometry analysis revealed that the CD8L cells were negative for the CD5 pan T-cell marker. It is suggested that these CD8LCD5- cells are natural killer (NK) cells similar to those found in the gut. An influx of CD8LCD5- cells was observed in leucocyte-infiltrated liver lesions at later stages of a rejection response to the cestode Taenia hydatigena.

Animals↗
PubMed1988

Lymphocyte phenotypes in the intestinal mucosa of sheep infected with Trichostrongylus colubriformis.

Monoclonal antibodies to ovine lymphocyte surface antigens were used in an immunohistochemical study of the intestine of sheep. In the epithelium CD8+ cells predominated whereas the majority of lamina propria T lymphocytes were CD4+. Infection of sheep with the parasitic nematode Trichostrongylus colubriformis including sufficiently large numbers of parasites to induce protective immunity did not alter the number of CD4+ or CD8+ lymphocytes in the intestinal mucosa. In contrast, exposure of naive sheep to a single large infection of T. colubriformis resulted in a substantial decrease in number of CD8+ cells and moderate decreases in number of CD4+ cells in the duodenal but not the jejunal mucosa. MHC class II antigens were not detected either in or on epithelial cells of the sheep small intestine.

Aging↗
PubMed1987

A functional and biochemical analysis of bovine class II MHC antigens using monoclonal antibodies.

Monoclonal antibodies (MAbs) reacting with bovine (2) ovine (3), murine (1) or human (1) Class II MHC antigens were examined for reactivity with bovine peripheral blood leucocytes (PBL) and lymph node cells (LNC) by immunofluorescence, immunoprecipitation and the capacity to inhibit mixed lymphocyte responses (MLR), lectin- and antigen-induced blastogenesis. The 6 MAbs identified comparable percentages of Class II positive lymphocytes in PBL (40.8 to 54.2%) and LNC (6 to 11.5%) regardless of BoLA-A phenotype. Immunohistological staining of Class II MAb was localized principally to the lymphoid follicles in lymph nodes and to isolated epithelial reticular cells in the thymus. The anti-Class II MAb immunoprecipitated alpha- and beta- chains of 26-29K and 32-34K, respectively. These MAb inhibited proliferative responses in the MLR by between 25 and 74%, and diminished blastogenesis induced by specific antigens (purified protein derivative + PPD and ovalbumin) and B-lymphocyte mitogens (PPD, lipopolysaccharide and dextran sulphate) by between 45 and 75%, regardless of BoLA-A phenotype. In contrast, proliferation in response to concanavalin A and phytohaemagglutinin were unaffected by the anti- Class II MAb. Similarly these MAb did not affect lysis by cytotoxic T-lymphocytes, the activity of which was depressed by anti-Class I MAbs and monospecific alloantisera.

Animals↗
PubMed1987

Sheep MHC class II molecules. I. Immunochemical characterization.

The physicochemical features, biosynthesis and glycosylation of sheep class II molecules were investigated using a panel of seven monoclonal antibodies. The class II molecules recognized by different monoclonal antibodies could be differentiated using SDS-PAGE. Two monoclonal antibodies, SBU.II 42-20 and 49-1, reacted with dissociated sheep class II molecules and recognized epitopes on class II alpha and beta polypeptides, respectively. The structure of the sheep class II heterodimer differed from that of mouse and man in that it was unstable in the presence of 1% SDS at 20 degrees and, following reduction, sheep beta polypeptides displayed a marked increase in MW, resulting in the apparent co-migration of reduced alpha and beta polypeptides on SDS-PAGE. This phenomenon was not seen using sheep class II molecules synthesized in the presence of tunicamycin. Pulse-chase analyses of biosynthetically labelled sheep class II molecules suggested the rapid association and glycosylation of sheep class II alpha and beta polypeptides during synthesis. Both alpha and beta polypeptides of sheep class II molecules carried N-linked oligosaccharides of MW 6,000 and 3,000, respectively. However, unlike human class II oligosaccharides, these were exclusively of the complex or sialylated type.

Acetylglucosaminidase↗
PubMed1984

An enzyme immunoassay for bovine brucellosis using a monoclonal antibody specific for field strains of Brucella abortus.

The success of various attempts to discriminate serologically between vaccinated cattle and those infected with field strains of Brucella abortus has been limited. A reliable assay that has this discriminating ability would greatly benefit the Australian Brucellosis Eradication Scheme. Studies of similar diagnostic problems have shown that species and strain-specific monoclonal antibodies with diagnostic potential can be produced. Therefore, the production of monoclonal antibodies specific for Br. abortus field strains was attempted. Spleen cells from Balb/C mice immunized with formalin-killed Br. abortus strain 544 were fused with P3/NSI-1 Ag4-1 cells using polyethylene glycol 4000. The resulting hybrid cells were screened by ELISA using soluble fractions of sonicated, heat-killed (60 degrees C, 1 h) bacteria as antigen. More than 200 cultures of hybrid cells contained detectable amounts of antibody to both field and vaccine strains of Brucella. However, one monoclonal antibody, Br 25, was found to bind field strains of Br. abortus biotypes 1 and 2, but not strain 19, Br. suis, Br. melitensis, or Br. ovis. The titre of Br 25 hybridoma cell culture supernatant is over 2 000, Br 25 cells injected into mice produce ascites fluid having titres of more than 100 000. A sandwich ELISA incorporating successive incubations of Br 25, soluble Brucella antigen, bovine sera and labelled anti-bovine immunoglobulin was developed. Sera from cattle that had been either vaccinated with strain 19 and infected were tested in the ELISA. In this ELISA most infected cattle were positive, whether vaccinated or not, whereas uninfected and vaccinated cattle were negative.

Animals↗