HISTOLOGICAL AND IMMUNOHISTOCHEMICAL FINDINGS IN THORACIC LYMPH-NODESOF CATTLE WITH CONTAGIOUS BOVINE PLEUROPNEUMONIA

Outbreaks of contagious bovine pleuropneumonia (CBPP) were reported in Lombardy, Northern Italy, at the end of 1990. For the purpose of this study, 54 slaughtered Holstein-Friesian cows showing typical lung les ions of CBPP from which tile small colony type of Mycoplasma mycoides subspecies mycoides (M. m. mycoides SC) was isolated, were selected. T horacic lymph nodes from these animals were sampled for bacteriologica l, histological and immunohistochemical analysis. Acute, subacute and chronic lesions were observed in 13, 12 and 29 cases, respectively. In the 13 animals showing acute lung lesions, an increased number of mac rophages was observed, especially in the subcapsular sinuses, but freq uently also in the cortical and medullary sinuses of the thoracic lymp h nodes; in all 13 acute cases ill. In. mycoides SC antigen was detect ed immunohistochemically in the cytoplasm of-the macrophages. In 10 ou t of tile 12 cases with subacute lung lesions, mycoplasma antigen was observed in macrophages located in sinuses, as well as in those scatte red in the lymph node parenchyma. Hyperplasia of germinal centres in f ollicles was observed histologically in most of the 29 cases with chro nic lung lesions. In immunohistochemically labelled sections, the char acteristic finding observed in 27 of the chronic cases, was the presen ce of a variable amount of positive material in the germinal centres. These findings demonstrate the involvement of thoracic lymph nodes in CBPP. (C) 1997 W.B. Saunders Company Limited.