Additionally, the frequencies of circulating PD-1+CXCR5+CD4+TFH cells were not significantly different between the children with acute HSP and HCs group, and the percentages of CXCR5+CD4+TFH cells and PD-1+CXCR5+CD4+TFH cells were not notably related with serum IgA, IgG, or IgM levels in acute HSP children or HCs, respectively. Here, PDCD1 is linked to hereditary spastic paraplegia.