Expression of monocyte chemoattractant protein-1 but not interleukin-8 in granulomatous lesions in lymph nodes from pigs with naturally occurring postweaning multisystemic wasting syndrome

Monocyte chemoattractant protein-1 (MCP-1) but not interleukin-8 (IL-8) was detected by in situ hybridization using a nonradioactive digoxigenin-labeled complementary DNA probe in granulomatous lesions of lymph nodes from 20 pigs with naturally occurring postweaning multisystemic wasting syndrome (PMWS). Complementary DNA probes of 375 and 266 base pairs for MCP-1 and IL-8, respectively, were generated by reverse transcription-polymerase chain reaction. The 20 pigs with PMWS had distinct positive hybridization signals for MCP-1 but not for IL-8. The hybridization signals for MCP-1 were strictly confined to the cells with granulomatous lesions, including macrophages and multinucleated giant cells, A very close cell-to-cell correlation between MCP-1 and porcine circovirus 2 was seen in serial sections of lymph nodes. Results of this study indicate that MCP-1 expression may play a role in the pathogenesis of granulomatous inflammation in pigs with PMWS.