Effects of plant induced-hipervitaminosis D on immune system organs and cells in experimentally intoxicated cattle

FONTANA PA, GIMENO EJ; LAGUENS GE; BARBEITO CG; DI GIROLAMO VMT; CORONATO S; PORTIANSKY EL.

Brasil

Congreso; ALAI; 2007

Solanum glaucophyllum (Sg) is a calcinogenic plant that causes “Enzootic calcinosis” in bovine livestock. Its main toxic principle is the 1,25-dihydroxyvitamin D. Calcitriol acts not only in calcium homeostasis, but in immune modulation and cell cycle regulation. The goal of the present work was to experimentally evaluate the modifications in cell proliferation and apoptotic index of immune system cells and to correlate them with the clinical parameters in Sg intoxicated heifers. Two years-old heifers received 25 g of Sg leaves powder twice a week during 15, 30 or 60 days. A group was intoxicated during 15 days but sacrificed at 60 days pi (recovery group). Control animals were sacrificed at 0 and 60 days. Blood calcium and leukocyte counting was determined. Phagocytosis tests, histochemistry (HE, Von Kossa) and immunohistochemistry (PCNA, TUNNEL, S100) of thymus, spleen, subiliac lymph nodes and isolated dendritic cells with morphometric analysis were performed. In the intoxicated animals characteristic illness signs were observed. Calcemia progressively increased and absolute leukocyte counting tended to drop. Total phagocytic index was progressively reduced. A significant decrease in the number of DC S100+ was observed. Thymus atrophy, reduction of cell number of spleen and lymph nodes and calcifications of the stroma were detected. PCNA was significantly reduced and the apoptotic index significantly increased. Recovery group animals showed similar patterns as those of control heifers. Our results suggest that hypervitaminosis D induces structural and functional alterations of the immune system, and that these changes correlate with the clinical status of the intoxicated animals.