693 Diagnosis of Neurosyphilis by Cerebrospinal Fluid Lymphocyte Phenotype C. Marra*, L. Tantalo, K. Dougherty, B. Wood Univ of Washington, Seattle
Background: HIV infection may increase the risk of neurosyphilis. Mild Cerebrospinal Fluid (CSF) pleocytosis can be due to HIV or syphilis and distinguishing between the 2 can be difficult if the CSF-VDRL is nonreactive. In normal HIV-infected and uninfected people, percentage of CSF B-cells is low. Increase in percentage of CSF B-cells is seen in neuro-Lyme. The goal of this study was to determine whether an increase in % CSF B-cells is also seen in neurosyphilis.
Methods: We divided 5-10 ml CSF samples into equal aliquots. One was centrifuged at 1000 rpm and the cell pellet resuspended in RPMI-10% FBS. The second was centrifuged at 1000 rpm, the pellet resuspended in 1 ml FBS-10% DMSO, frozen overnight at -80C, and stored in liquid N2. The fresh sample was examined for CD3, CD4, CD8, CD19, and CD45 by flow cytometry on the day of collection. The frozen sample was thawed after 7-10 days, washed once in RPMI-10% FBS, and similarly examined. Association between continuous variables was assessed by Spearman correlation and means by Mann-Whitney U test.
Results: Twenty-eight (28) individuals with syphilis underwent lumbar puncture. Of these, 21 were HIV-infected, 8 had late latent, and the remainder had primary (1), secondary (14) and early latent (5) syphilis. Twenty-five (25) paired fresh and frozen samples were available. Because the percentage of CD19 was highly correlated between the 2 (p = 0.004), results from frozen samples were used in this analysis. The percentage of CD19 did not differ by syphilis stage but was significantly higher in those with reactive CSF-VDRL (p = 0.05) and those with higher CSF WBC (p = 0.02). Mean percentage of CD19 (SD) in 14 subjects with normal CSF (WBC = 5/ul, protein = 45 mg/dl, CSF-VDRL nonreactive) was 5.21 (3.51). To determine sensitivity and specificity, we defined elevated percentage of CD19 by > 15.75 (mean + 3SD of normal), and we defined neurosyphilis as CSF WBC > 20/ul or a reactive CSF-VDRL. Elevated percentage of CD19 was specific (100%) but not sensitive (50%) for diagnosis of neurosyphilis. Two (2) subjects with CSF pleocytosis (27/ul and 67/ul), but nonreactive CSF-VDRL, had elevated percentage of CD19. In 2 subjects studied before and after neurosyphilis therapy, elevated percentage of CD19 declined to normal.
Conclusions: The percentage of CSF B-cells may help diagnose neurosyphilis in situations where the CSF-VDRL is nonreactive. This test may be particularly useful in HIV-infected patients. Cryopreserved samples can be used.
