There were significant differences in the distribution and proportions of a variety of immune cells between COVID-19 and healthy controls, including activated CD4 T cells, macrophages, neutrophils, activated B cells, activated CD8 T cells, CD56 bright natural killer cells, eosinophils, etc. Analysis of the differences between SLE and healthy controls revealed a significantly higher infiltration of neutrophils in the peripheral blood of SLE. Here, CD4 is linked to systemic lupus erythematosus.