Abstract. This study covered a population of 91 cows aged 3–6 years. Enzootic bovine leukaemia (EBL) was diagnosed with ELISA and PCR tests. The assays were performed in the 1st, 2nd, and 3rd month after calving. Use was made of anti-bovine monoclonal antibodies (Mab), (VMDR Inc. Pullman-USA) and conjugates of FITC and R-PE (Medac – Germany) with an indirect immunofluorescence reaction (IMF). A differentiation observed between the population numbers of CD19 + B lymphocytes and CD2 + T lymphocytes as well as the CD8 + T lymphocyte sub-population was found to be significant between cows with different genotypes of AcP. Moreover, a correlation was found between the polymorphism of AcP and EBL incidence in cows with reference to the number and percentage of CD19 + B lymphocytes (AcP polymorphism x EBL interaction). A significant differentiation in the profile of peripheral blood lymphocytes was observed between EBL-positive and EBL-negative cows as well as over the first three months after calving. The results reported in this study seem to indicate the potential contribution of a genetic predisposition connected with the expression of biological functions of the blood leukocyte acid phosphatase system in the activation and proliferation of these cells.

The aim of this study was to determine whether SNP at position -824 (promoter region) of the TNFα gene significantly differentiates the size of IgM+, CD5+ and CD11b+ cell subpopulations and affects the expression of membrane-bound TNFα protein (mTNFα) on these cells and their susceptibility to BLV infections.In this study, significant differences were determined for the first time between TNFα genotypes and the percentage of cells with the CD11b+TNFα+p24+ immunophenotype. Furthermore, greater expansion of lymphocytes with the IgM+TNFα+p24+ immunophenotype was reported in cows with the G/G genotype than in A/A homozygotes. Cells with the above immunophenotype were more frequently observed in cows with persistent leukocytosis than in aleukemic cattle.Our results suggest that polymorphism of the TNFα -824 A>G gene and mTNFα protein expression play an important role in the pathogenesis of enzootic bovine leukosis.

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The objective of this study was to describe and compare the genetic structure (TNF-α -position 824) of dairy cattle herds infected and not infected with the bovine leukemia virus (BLV). The results of the present study indicate that BLV-positive herds were characterized by similar genetic structure (TNF-α -824A/G). The genetic equilibrium in these herds was preserved, but a tendency to increased frequency of G/G homozygotes was found. The genetic structure of the healthy herd differed considerably from that of leukemic herds.