Association of elevated lymph node cell release of histamine and tumor necrosis factor with genetic predisposition to limb edema formation in dogs infected with Brugia pahangi.

Brugia pahangi infection in the canine rear limb results in marked lymphatic duct and popliteal lymph node pathologic changes. Limb edema is variably associated with infection and does not correlate well with duct or node lesions. To understand the mechanisms of limb edema, lymph node cells were collected by sequential biopsy following infection and examined for production of inflammatory mediators. Lymph node cells from a litter of dogs selectively bred with a high incidence of edema formation (82%) demonstrated spontaneously released histamine and prostaglandin E2 levels higher than those of closely related nonedema-forming dogs (0-20%) and/or control dogs. These edema-forming dogs also showed elevated release of tumor necrosis factor-alpha when cells were cultured with Brugia antigen. Toluidine blue staining of infected lymph node sections revealed that the edema-forming dogs had higher numbers of mast cells than infected lymph nodes of nonedema-forming dogs.