Alveolar macrophage functions during the transition phase to active immunity in calves1.

The first 3 to 6 mo of the life of calves is the period during which active immunity is established. During this period, greater morbidity and mortality is caused by bronchopneumonia because of the immaturity of the pulmonary immune system or the exaggerated cytotoxic response at subsequent infection. The aim of this study was to examine the maturity of the immune system during this phase of activation of acquired immunity in calves. For this purpose, the functions of phagocytosis and the reactive oxygen species (ROS) of alveolar macrophages CD14+ were evaluated. Further, the classes of immunoglobulins and the cytokines implicated in lymphocyte response patterns Th1 and Th2 in 10 healthy Holstein calves were quantified. Samples were taken from calves every 15 d, from the third to the sixth month of life. The alveolar macrophage CD14+ functions increased progressively until 150 d of age (phagocytosis, P = 0.02, ROS, P = 0.05), IgG1 and IgG2 isotype secretion reached an equilibrium, and the cytokine profiles were compatible with the Th1 response. At 165 d of age, there was a decrease in cellular function (phagocytosis P = 0.02, ROS P = 0.04) and an increase in IgG1 titers (P = 0.005) and IL-10 mRNA expression (P = 0.09). At 180 d of life, we observed an IgG1 and IgG2 secretion balance, a decrease in IL-10 mRNA expression, and an increase in IL-12 mRNA (P = 0.04) and tumor necrosis factor (TNF)-α mRNA expressions (P = 0.0003) and alveolar macrophage oxidative metabolism were observed. These results indicate that the calves had an active immune response that was distinctive for the age group. The CD14+ response is more reactive at 150 d. A regulatory and/or humoral response begins at 165 d of life as the equilibrium of Th1 and Th2 profiles is reached at 180 d of life. This may be clinically relevant for the development of specific therapies and prophylactic measures for bronchopneumonia in calves at 135 to 180 d of life.

Influência da suplementação de vitaminas A, D e E na função imune de bezerros alimentados com dieta á base de feno capim tifton (cynodon spp) / Influence of A, D and E vitamin supplements on immune function of calves fed diet tifton (cynodon spp) hay

As vitaminas são compostos orgânicos necessários em poucas quantidades no organismo, todavia indispensáveis para as funções metabólicas. Elas se inserem em inúmeras reações metabólicas, fisiológicas e imunes das células, necessárias para a manutenção da saúde animal, além de atuarem como imunoestimulante. Embora a dieta rica em folhagens verdes frescas forneça quantidades suficientes de vitaminas A, D e E a suplementação intensiva com alimentos conservados na forma de feno ou silagem pode reduzir em até 50 % dos teores destas vitaminas no alimento. Diante disso, a proposta do trabalho foi verificar se a administração parenteral de vitaminas A, D e E age como imunoestimulante em garrotes estabulados e alimentados exclusivamente com feno de tifton. Para tanto 14 bovinos foram divididos em dois grupos homogêneos, sendo o grupo S, suplementado com vitamina A, D e E em dose única de 30 mL por via intramuscular; e o grupo C, sem suplementação. Ambos os grupos foram alojados em baias parcialmente privadas de sol, e alimentados com feno por um período de três meses. A avaliação imune foi realizada por hemogramas e ensaio de função leucocitária (metabolismo oxidativo e fagocitose) nos momentos antes do tratamento, três e dez dias após os tratamentos. Tendo em vista que a suplementação com polivitamínicos A, D e E aumentou a porcentagem da atividade de células granulocítica e a intensidade da atividade de células mononucleares, além de intensificar o efeito antioxidante prolongando a sobrevida de hemácias e neutrófilos, conclui-se que esta suplementação promoveu efeito benéfico na resposta imune de bezerros da Raça Holandesa, apesar dos efeitos deletérios da alimentação exclusiva com feno e da privação parcial da incidência solar direta.

Vitamins are organic compounds which are required in small quantities in the body, however essential for the metabolic functions. They participate in numerous metabolic reactions, physiological and immune cells, needed to maintain animal health, as well as act as immunostimulants. Although the diet rich in fresh green foliage provides sufficient amounts of vitamin A, D and E, intensive supplementation with food stored in the form of hay or silage can reduce up to 50% of the levels of these vitamins in food. Given this, the proposal of this study was to verify how the parenteral administration of vitamins ADE acts as immunostimulant in steers fed exclusively with hay of tifton. For that, 14 cattle were divided into two homogeneous groups: Group S, supplemented with vitamin A, D e E given in a single intramuscular dose of 30mL, and Group C without supplementation. Both groups were housed in private stalls and fed with hay for a period of three months. Immune evaluation was performed by blood count and testing of leukocyte function (oxidative metabolism and phagocytosis) in the moments before treatment, three and ten days after the treatments. Considering that supplementation with vitamin A, D e E increased the percentage of granulocytic cell activity and the intensity of the activity of mononuclear cells, as well as intensified the antioxidant effect prolonging the survival of red blood cells and neutrophils, it can be concluded that this treatment had a beneficial effect on the immune response of Holstein calves, despite the damaging effects of exclusive feeding hay, and the partially deprivation of solar incidence.