“Determination of iga levels in serum and cerebrospinal fluid: assessment of its diagnostic value for canine steroid-responsive meningitis-arteritis”

Steroid-responsive meningitis-arteritis (SRMA) is a systemic inflammatory disease of young dogs resulting from a dysregulation of the immune system. Previous neuroimmunological studies suggested that concomitant elevation of IgA levels in both serum and CSF are specific for SRMA throughout the different stages of the disease and also during long-term treatment with glucocorticosteroids. Other recent studies, however, raised concerns over the value of this test. The purpose of this study was therefore to verify our previous results in a large number of cases and to determine the diagnostic value of IgA level testing in paired cerebrospinal fluid (CSF) and serum samples. We compared IgA levels of dogs with SRMA with dogs affected by various other diseases and calculated sensitivity and specificity of the test. IgA content of 1050 canine CSF and serum samples were evaluated. Paired samples derived from 311 dogs with SRMA and 214 dogs with other diseases such as other central nervous system (CNS) inflammatory diseases (n = 34), neoplasia of the CNS (n = 46), idiopathic epilepsy (n = 42), intervertebral disc disease (n = 46) and diseases not affecting the CNS (n = 46). Serum IgA levels were significantly higher in dogs in the acute form of SRMA in comparison to dogs with other diseases. This was also found evaluating IgA levels in the CSF, with the exception of the inflammatory CNS diseases, in which the IgA content did not differ significantly from those with SRMA. The sensitivity for simultaneous elevation of IgA levels in serum and CSF was 91 % with a specificity of 78 %, respectively. Analyses of a large number of samples confirmed that IgA production is higher within the group of dogs with SRMA when compared to the remaining disease categories examined. Calculation of the diagnostic value of the determination of IgA confirmed that this test is still an important tool and highly sensitive to confirm the diagnosis of SRMA. Testing paired CSF and serum samples for IgA is recommended for the diagnostic work-up in suspected cases of SRMA, particularly in those animals that received glucocorticosteroids prior to CSF puncture. However, since the specificity is not high, other diseases causing neck pain have to be ruled out in the protracted form.