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Abstract

Bovine cells from cattle infected with Theileria annulata were phenotyped with monoclonal antibodies recognizing bovine leukocyte antigens. Macroschizont-infected, transformed cell lines prepared from peripheral blood mononuclear cells of cattle, infected with sporozoites, were assessed by flow cytometry; parasitized cells in tissues from infected cattle were examined by immunocytochemical techniques. Co-expression of markers for different cell lineages by the cell lines precluded a definite conclusion as to their phenotypic origins. For, while the pattern of leukocyte antigens expressed by these in vivo-derived schizont-infected cells, which included CD11b, was indicative of a myeloid origin, the possibility that they were NK cells could not be excluded. The monoclonal antibody (MAb) IL-A15, which recognizes CD11b, reacted with a high proportion of parasitized cells in sections of tissues from infected cattle at all stages of acute disease. Mononuclear cells infected with parasites at all stages of differentiation, from macroschizont to microschizont, expressed CD11b. Such parasitized cells occurred throughout the lymphoid tissues, being found in the thymus, spleen and lymph nodes, particularly the prescapular node draining the site of infection, the hepatic, mesenteric and precrural nodes, as well as in the reticulo-endothelial tissue of the liver, kidney, lung, abomasum, adrenal and pituitary glands. These observations provided the first evidence for a myeloid origin for the parasitized T. annulata cells found in infected bovine tissues and blood and suggested a mechanism whereby schizonts could transfer from cell to cell during mechanical infection with schizont-infected cells.

Clinical Pathology, Immunopathology and Advanced Vaccine Technology in Bovine Theileriosis: A Review

“…Theileria annulata infections are usually fatal, especially in susceptible, imported or naïve cattle [ 93 ]. The death of affected cattle is attributed to the transformation and proliferation of schizont-infected mononuclear cells and/or haemolytic anaemia resulting from the intracellular piroplasms [ 94 ].…”

“…Previously, some authors have stated that the fatality due to infection is greatly dependent on the overproduction of cytokines, such as TNF-α produced by the schizont-infected monocytes/macrophages and uninfected macrophages [ 95 , 96 ]. The excess cytokines are responsible for pathologies associated with tropical theileriosis [ 93 , 95 , 96 ]. Tissue response in all lymphoid organs is a macrophagic hyperplasia.…”

“…Tissue response in all lymphoid organs is a macrophagic hyperplasia. No transformed T cells were found in the lymphoid tissues of T. annulata -infected cattle when compared to the lymphoid tissue of cattle infected with T. parva , where an extensive population of lymphoid cells were present [ 93 ]. The immune subversion process in immunocompromised or susceptible cattle is induced by a protozaoal superantigen expressed on the schizont-infected lymphocytes.…”

“…Interestingly, the levels of T cell proliferation induced by infected cells correlated with the level of expression of the T cell stimulatory cytokines IL-1α, IL-1β, and IL-6 [ 98 ]. T. annulata schizonts predominately have an affinity for CD3 − CD11b + phagocytic cells [ 93 ], which express major histocompatibility class (MHC) II antigens [ 97 ]. In vivo, T. annulata -infected mononuclear cells are found throughout the lymphoid organs, and their metastasis is due to their expression of MMP [ 101 ] and of adhesion molecules such as CD2, CD 11b, followed very late by the expression of antigen 4 (VL4) and CD9 [ 93 ].…”

Pakistan’ın Cholistan Çölünde Başıboş Dolaşan Cholistan Sığırlarında Tropikal Theileriosisin Prevalansı ve Kan Değerleri

“…Research has been conducted in Pakistan on various aspects of this disease in Sahiwal and crossbred cattle [6] , as well as in sheep and goats [9] . It is a serious constraint to cattle production in endemic areas, causing lethal infections in exotic cattle and considerable mortality in indigenous as well as in crossbred stock [10] . Factors including Pakistan's location in a warm climate and extensive uncontrolled crossbreeding programmes have rendered it an endemic area for theileriosis [6] .…”