Cerebrospinal fluid B lymphocyte identification for diagnosis and follow-up in human African trypanosomiasis in the field

Abstract

Objectives: In human African trypanosomiasis (HAT, sleeping sickness), staging of disease and treatment follow-up relies on white cell count in the cerebrospinal fluid (CSF). As B lymphocytes (CD19 positive cells) are not found in the CSF of healthy individuals but occur in neurological disorders such as multiple sclerosis, B lymphocyte count may be useful for field diagnosis/staging and therapeutic follow-up in HAT. Methods: Seventy-one HAT patients were diagnosed and 50 were followed-up 6-24 months after treatment. White cell counts were used for conventional staging (stage 1, ≤5 cells/μl CSF, n = 42; stage 2, ≥20 cells/μl, n = 16) and intermediate stage (6-19 cells/μl, n = 13). Slides containing 1 μl of CSF mixed with Dynabeads® CD19 pan B were examined microscopically to detect B cell rosettes (bound to at least four beads). Results: Stage 1 patients exhibited zero (n = 37) or one CSF rosette/μl (n = 5), contrary to most stage 2 patients (14/16: ≥2 rosettes/μl). Intermediate stage patients expressed 0 (n = 9), 1 (n = 3) or 2 (n = 1) rosettes/μl of CSF. During follow-up, rosette counts correlated with white cell count staging but were much easier to read. Conclusion: B cell rosettes being easily detected in the CSF in field conditions may be proposed to replace white cell count for defining HAT stages 1 and 2 and limit uncertainty in treatment decision in patients with intermediate stage. © 2009 Blackwell Publishing Ltd.