RESUMEN
As immunosuppression in pigeons is common and results in reduced post-vaccination immunity and lower health status of the birds, studies have been taken up aimed at evaluation of the effect of three doses of methisoprinol on the percentage of CD4+ and CD8+ T lymphocyte subpopulation in peripheral blood and in the spleen and the titre of anti-NDV antibodies in the serum of pigeons in four groups (A, B, C, D), with 20 birds each. Pigeons in each group were immunised against paramyxovirosis at week 6 and 9 of life. Water for injection (group A - control) or methisoprinol at 100 mg/kg of body weight (group B), 200 mg/kg of body weight (group C) and 600 mg/kg of body weight (group D) was administered intramuscularly for 3 days before each vaccination. The immunological analyses were carried out by flow cytometry and the ELISA test. The findings indicate that methisoprinol administered intramuscularly at 100 and 200 mg/kg of body weight for 3 successive days before vaccination against paramyxovirosis mainly stimulates the mechanisms of non-specific humoral and cellular immunity, which is indicated by a higher percentage of the subpopulation of CD4+ T lymphocytes in peripheral blood and in the spleen and a higher titre of anti-NDV antibodies.