[Bovine enzootic leukemia and study of c-type particles in a cow with acute lymphatic leukemia and in cattle of the same herd with persistent lymphocytosis].

A case of acute lymphatic leukemia in a 7-month-pregnant Italian Friesian cow, aged about 6 years and belonging to a small dairy herd of 11 cows is described. Hematologic, histopatologic and ultrastructural examinations were performed, the ultrastructural studies were confined to the lymphnodes, thymus and buffy-coat cultures from peripheral blood. The remaining animals were subjected to hematologic examination and electron microscopy examination of buffy-coat cultures from peripheral blood. C-type particles were found in phytohemagglutinin (PHA)-treated and untreated buffy-coat cultures from the leukemic cow and from the animals with persistent lymphocytosis. C-type particles were also found in milk samples from 3 cows with persistent lymphocytosis.