CXCR5 and tropical spastic paraparesis: As memory Tfh cells have been reported to promote B cell growth, differentiation and class switching and to resemble tissue Tfh cells [32, 33, 35], we examined whether CXCR5-expressing memory Tfh cells are present in the CSF and peripheral blood of HAM/TSP patients compared to NDs, ACs and patients with the other chronic virus infection and/or neuroinflammatory diseases.