Immune infiltration analysis revealed that HF patients exhibited a higher abundance of resting mast cells, resting NK cells, CD8T cells, resting memory CD4 T cells, activated memory CD4 T cells, M1 Macrophages, naive CD4 T cells, M0 Macrophages, regulatory T cells (Tregs), follicular helper T cells, Monocytes, and activated NK cells, and a lower abundance of plasma cells, neutrophils, and eosinophils (P < 0.05 and FDR<0.05). The gene discussed is CD4; the disease is hydrops fetalis.