In order to explore the reasons for the reduced HPK1 in SLE Tfh cells, the H3K27me3 enrichment in HPK1 promoter region was detected, and it was found that the H3K27me3 number in this region of Tfh cells from SLE patients increased strikingly, and it was negatively correlated with the mRNA and protein expressions of HPK1. The gene discussed is MAP4K1; the disease is systemic lupus erythematosus.