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Bovine leucocyte's were assayed for their cytotoxic activity against Trypanosoma theileria, a large haemofiagellate parasite of cattle. Cytotoxicity was assessed by 'H-uridine release from pre-labelled parasites and also by light microscopy. Cytotoxicity proved to be totally dependent upon the presence of specific antibody. Serum and the immunoglobulin fraction of colostrum from normal adult cattle and serum from normal colostrum fed calves mediated cytotoxicity: serum from SPF colostrum deprived calves possessed no cytotoxic activity. Neutrophils. eosinophils. monocytes and macrophage's obtained from both the peripheral blood and mammary gland of heifers were cytotoxic to T. thcileri epimastigotes. Lymphocytes failed to mediate cytotoxicity either in the presence or absence of specific antibody. Despite the large size of this trypanosome all effector cells phagocytosed T. theileri. Phagocytosis by macrophage's and eosinophils preceded specific isotope release, however neutrophils mediated 50",, specific isotope release during the phagocytic period, suggesting extracellular cell-mediated lysis. [ABSTRACT FROM AUTHOR]

Cattle, infected with Fasciola hepatica metacercariae, produce antibodies against the outer glycocalyx of freshly excysted juvenile F. hepatica. Using 51Cr-release and viability assays such antibodies in the presence or absence of bovine complement did not cause discernible damage to the parasite. The presence of excess antibody caused the build-up of large aggregates of antigen-antibody complexes over the parasite surface: these aggregates were eventually shed into the medium. Neutrophils and eosinophils were obtained by selective stimulation of the mammary gland of heifers, and attached in large numbers to flukes coated with either IgG1 or IgG2. Attachment was dependent on Fc receptors although the adherence of the eosinophils was more prolonged than that of the neutrophils. Using 51Cr-release and viability assays no damage occurred to the flukes using either eosinophils or neutrophils in antibody-dependent cell-mediated cytotoxicity; adherent granulocytes were eventually shed. It is suggested that the rapid turnover and excretion of the outer glycocalyx of juvenile flukes prevents the intimate attachment of granulocytes to the helminth parasite, which is perhaps a prerequisite for cell-mediated damage to occur. [ABSTRACT FROM AUTHOR]

Eosinophils were isolated from the mammary gland of Fasciola hepattca-infected cattle by intramammary infusion with a crude extract from adult F. hepatica. Up to 5 × 109 eosinophils with a purity of over 90% could be obtained from a single quarter of the gland. The major contaminating cells were monocytes which reached their peak several days following the eosinophil peak. Two major proteins were isolated from bovine eosinophil granules, a high molecular weight peroxidase-active protein and a smaller molecular weight predominantly basic protein. This smaller protein was thought to be the bovine equivalent of guinea-pig and human major basic protein (MBP). although it possessed an unusually high concentration of cysteine. The bovine MBP had a profound effect on juvenile F. hepatica in vitro causing damage and death at concentrations down to 1 × 10-6 M. The damage was detected by a 51Cr release assay and/or a viability assay involving microscopical examination of the flukes. Other cations, especially protamine sulphate, were also shown to kill flukes, although both lysozyme. found in neutrophils. and the peroxidase-positive peak from bovine eosinophils were unable to mediate any detectable damage. [ABSTRACT FROM AUTHOR]

Observations were made on a bovine lymphoblast cell culture line, C2, permanently infected with the protozoan parasite Theileria parva. No specific parasite antigen was detected on the C2 cell surface, either by a fluorescent technique or by antibody-dependent cell-mediated cytotoxicity. There was no detectable surface immunoglobulin or secretion of immunoglobulins into the tissue culture medium. Using immunofluorescence and calf thymus and bone marrow antisera, C2 cells were found to share a membrane antigen with normal calf thymus cells, and also to possess a strong transplantation antigen. Bovine antisera against the latter antigen can initiate killing of C2 cells by normal bovine mononuclear leucocytes in antibody-dependent cell-mediated cytotoxicity. C2 cells can also act as weak stimulators in a mixed leucocyte reaction. The possible role of such transformed parasite-infected lymphoblasts in the strong functional immunity that follows recovery from Theileria parva infection is discussed. [ABSTRACT FROM AUTHOR]

The aim of this study was to produce monoclonal antibodies (mAb) recognizing equine lymphocyte surface antigens. Fusions were conducted using BALBjc mice hyperimmunized with equine thymocytes. Hybridoma supernatants were screened by flow cytometry and positive hybridomas were cloned twice by limiting dilution. These mAb were then characterized for tissue distribution by immunohistology and flow cytometry, and by precipitation and analysis of the lymphocyte antigens which they recognized. Three mAb (CVS5, CVS4 and CVS8) are described which recognize only T lymphocytes in peripheral blood. Two-colour immunofluorescent studies showed that CVS5 recognized all T lymphocytes and that CVS4 and CVS8 recognized two mutually exclusive subsets of CVS5-positive cells. In the thymus there was a large population of CVS4/CVS8 double-positive cells. lmmunohistochemical staining with these mAb was restricted to T-lymphocyte areas. CVS4 and CVS5 precipitated molecules of 58,000 and 69,000 MW, respectively, in both reducing and non- reducing conditions. CVS8 precipitated two molecules of 32,000 and 39,000 MW in reducing conditions, and one molecule of 69,000 MW in non-reducing conditions. This evidence suggests that CVS5, CVS4 and CVS8 recognize the equine homologues of CD5, CD4 and CD8, and that the characteristics of these antigens are similar to those of other species. [ABSTRACT FROM AUTHOR]

Up to 50% of the blood lymphocytes in young pigs are thymus-derived, lack all subset-specific markers and appear immunologically unresponsive, with no known functional role. In an examination of their possible role in natural killing, NK activity was found in unpurified mononuclear cells and in preparations of unselected and nylon non-adherent lymphocytes (T cells and Null cells). However, NK activity was abolished by removing the E rosette forming T cells using a rat IgM anti-pig CD2 monoclonal antibody and rabbit complement, but not by control treatments with a non-binding rat IgM monoclonal reagent and complement or with any other reagent alone. Thus the resting Null T cell appears not to play a significant role in natural killing. [ABSTRACT FROM AUTHOR]

Summary. Twenty chickens were immunized with heat killed Salmonella gallinarum. Buffy coats removed at daily intervals during a post-immunization period of 15 days were examined quantitatively and qualitatively for the presence of cells involved in any specific immune reaction (immunocytes). These were detected by an immunocyto-adherence technique modified to permit a morphological examination of the immunocytes. On the basis of this examination the circulating immunocytes were classified into three main classes: haemocytoblasts, plasmacyte series cells and lymphocyte series cells. The significance of the results is discussed in relation to the possible functions of these cells in the immune response. [ABSTRACT FROM AUTHOR]

Following oral infection of a 12-week-old chicken with an overnight broth culture of Salm. gallinarum, serum was removed on the 9th day and tested for the presence of haemagglutinating antibody using erythrocytes modified with a Westphal lipopolysaccharide extract of Salm. gallinarum. The serum was found to have a high titre and on ’Sephadex’ fractionation and ultracentrifugal preparation showed a marked IgM response. Spectrophotometric measurements were made of interactions between the O-antigen extract and the whole serum or its component IgM and IgG fractions. Hapten-antibody complexes were measurable with the whole serum and the IgM fraction, but no complexes were detected with the IgG fraction under the conditions of the experiment.

The treatment of Carworth Wistar rats with normal equine IgG or ALG pre-absorbed with sheep erythrocytes sensitized the rats to sheep erythrocytes and prevented ALG from suppressing the primary immune response to this antigen. [ABSTRACT FROM AUTHOR]