CXCR5 and hereditary spastic paraplegia: These findings implied that increased percentages of CXCR5+CD4+TFH cells and ICOS+CXCR5+CD4+TFH cells in acute HSP children might contribute to inducing IgA production which could cause the formation of IgA-containing immune complexes that promoted the development and progression of children during the acute stage of HSP.