ICOS and systemic lupus erythematosus: Frequencies of CD4+CXCR5+CD45RA-effector cTfh cells, PD1+cTfh, PD1+ICOS+cTfh, PD1+cTfh1, PD1+cTfh2, PD1+cTfh17, and PD1+ICOS+cTfh1 cells as well as plasmablasts showed significant differences among HC, active and inactive SLE patients.