Pathogenetic factors for excessive IgA production: Th2-dominated immune response in canine steroid-responsive meningitis-arteritis.

Canine steroid-responsive meningitis-arteritis (SRMA) is a systemic inflammatory disease with a predominant manifestation within the cervical meninges, increased immunoglobulin A (IgA) levels in serum and cerebrospinal fluid (CSF), and a shift of the B:T cell ratio towards a higher percentage of B cells. A Th2-dominated immune response associated with SRMA was therefore hypothesised. Pellets of peripheral blood mononuclear cells (PBMNCs) and CSF white blood cells (CSF WBCs) from dogs in the acute phase of SRMA (n=16) and under glucocorticoid treatment for SRMA (n=16) were investigated for interleukin (IL)-2, interferon (IFN)-γ, IL-4, IL-5 and IL-10 mRNA expression by means of reverse-transcriptase real-time polymerase chain reaction. Results were compared with those of dogs with other inflammatory (n=9) and neoplastic disorders (n=10) of the central nervous system. A tendency towards low levels of Th1 response related cytokines (IL-2, IFN-γ) and high IL-4 expression was observed indicating a Th2-skewed immune response. The pronounced IL-4 production may be an important pathogenetic factor for excessive IgA production in the acute phase of SRMA and for those cases under glucocorticoid treatment.