Analysis of cerebrospinal fluid cells by flow cytometry and immunocytochemistry in inflammatory central nervous system diseases: Comparison of low- and high-density cell surface antigen expression

The examination of cerebrospinal fluid (CSF) continues to play an important role in the diagnosis of inflammatory diseases of the central nervous syst em (CNS). Immunocytochemistry and flow cytometry are the most commonly used methods for analysis of surface markers on CSF cells. We here compared the se methods in the examination of CSF cells from a total of 68 patients with acute and chronic inflammatory CNS diseases. Expression of costimulatory m olecules CD80 (B7-1) and CD86 (B7-2) as activation markers that are present at low density on the cell surface was analyzed in comparison to CD22 (B-c ells) and CD4 (T-cell subset), that show high staining intensities. For CD2 2 and CD4, the results obtained with both methods were similar and reliable . Using flow cytometry, CD80 expression was detected in 6% of CSF cells in patients with chronic inflammatory CNS disease, as compared to 2% using imm unocytochemistry, where the reliability of the data was found to be higher. We conclude that for examination of low-density surface markers on CSF cel ls, particularly with low cell counts, immunocytochemistry, may be more rel iable. Diagn. Cytopathol. 1999;21:313-318. (C) 1999 Wiley-Liss, Inc.