Hydrogen peroxide release by phagocytes from healthy and infected bovine mammary gland/Liberacao de peroxido de hidrogenio por fagocitos de glandulas mamarias bovinas higidas e infectadas

The purpose of the present study was to evaluate the hydrogen peroxide ([H.sub.2][O.sub.2]) release by phagocytes from infected and uninfected mammary glands in dairy cows. Thus, milk samples from 73 quarters were divided in healthy and infected samples according to bacteriological culture and somatic cell count (SCC). After separation of milk cells, the samples were submitted to differential SCC and hydrogen peroxide release by oxidation of phenol red. There was a lower [H.sub.2][O.sub.2] release by phagocytes from infected quarters, as well as, a negative correlation between the [H.sub.2][O.sub.2] release by phagocytes and SCC (r=-0.34; P=0.0025) and percentage of neutrophils (r=-0.24; P=0.04). Furthermore, it was observed a tendency toward a lower [H.sub.2][O.sub.2] release by phagocytes stimulated by phorbol 12-myristate 13-acetate in the infected quarters. However, a higher [H.sub.2][O.sub.2] release by phagocytes was observed in milk samples from infected quarters by the estimation of the [H.sub.2][O.sub.2] release by phagocytes in 1mL of milk according to SCC [mL.sup.-1] of each sample. The present study showed a decrease in [H.sub.2][O.sub.2] release by the infected quarters which indicate lower microbicidal activity. However, the higher [H.sub.2][O.sub.2] release by phagocytes in 1mL of milk in the infected quarters may contribute to recruitment of leukocytes to the site of infection and the persistence of infection. Key words: bovine, mammary gland, mastitis, oxidative metabolism, phagocytes. O objetivo do presente estudo foi avaliar a capacidade de liberacao de peroxido de hidrogenio (HfOJ por fagocitos oriundos de glandulas mamarias bovinas sadias e infectadas. Desse modo, 73 amostras de leite provenientes das glandulas mamarias foram classificadas em sadias e infectadas de acordo com a cultura bacteriologica e a contagem de celulas somaticas (CCS). Apos o isolamento das celulas do leite, procedeu-se a contagem diferencial de leucocitos e determinacao da liberacao de [H.sub.2][O.sub.2] pela oxidacao da solucao de vermelho fenol. Foi observada menor liberacao de [H.sub.2][O.sub.2] pelos fagocitos oriundos dos quartos mamarios infectados, assim como houve correlacao negativa entre a liberacao de [H.sub.2][O.sub.2] por fagocitos e a CCS (r=-0,34; P = 0,0025), e a porcentagem de neutrofllos (r=-0,24; P=0,04). Alem disso, houve tendencia de menor liberacao de [H.sub.2][O.sub.2] pelos fagocitos estimulados por forbol 12-miristato 13-acetato nas gland