Abstract. In Black-and-White cattle, polymorphism of blood leukocyte acid phosphatase (AcP) is determined by a pair of autosomal alleles. Blood leukocyte AcP polymorphism exhibits a correlation with the white cell composition and the granulocyte metabolic efficiency in clinically healthy animals. The aim of the study was to determine the relationship between the AcP polymorphism and the lymphocyte proliferation response capacity in the first three months after calving of cows naturally-infected with bovine leukaemia virus. The study covered 61 Black-and-White cows originating from one herd. The ELISA and PCR tests were used in the diagnosing BLV infections. Additionally agarose gel electrophoresis was used to determine the AcP polymorphism and the lymphocyte proliferation efficiency was determined based on the lymphoblastic transformation test using the isotope method.

The obtained results suggest that the product of blood leukocyte acid phosphatase gene is likely to participate in the lymphocyte activation and proliferation and that there is an association between the biological function expression of the AcP gene product and the cows' susceptibility to infection with bovine leukaemia virus. Moreover, the results obtained seem to indicate that the correlation of both factors − the bovine leukaemia virus and the month of lactation − modifies the proliferation response of the phytohaemagglutinin unstimulated lymphocytes.