Caseous lymphadenitis (CL) is a chronic disease that affects sheep and goats worldwide. CL causes a large economic loss to producers via milk and fiber losses, carcass condemnation, and chronic wasting of animals. Corynebacterium pseudotuberculosis (C. psTB) causes CL, and infected animals produce abscesses, typically in lymph nodes, lungs, liver, and mammary tissues. Ruptured abscesses release C. psTB, and can contaminate the environment. The bacteria are extremely hardy and can survive in the external environment for over a year, infecting other animals through open wounds.
Macrophages engulf C. psTB when it enters the body, and carry it to the lymph nodes. Corynebacterium pseudotuberculosis possesses some mechanisms that prevent lysis by the macrophages. When C. psTB reaches the lymph tissues, many immune cells attack the area, and this causes the abscesses. Recent studies suggest that some individual animals are resistant to clinical CL. To test this phenomenon, we collected blood from cattle and sheep, developed a protocol for macrophage culture, and produced CL antigens to challenge the macrophages. We tested macrophage cytokine (IL10) response to stimulation with antigens using a commercial Enzyme Linked Immunosorbent Assay (ELISA). There was no measureable IL10 response detected. Future work will evaluate other cytokines (IL8) and will investigate genetic (NOD2) resistance to CL.
Fish, Amy, "The Role of Macrophages in Resistance to Caseous Lymphadenitis" (2015). Honors College. 214.