Tofacitinib (TOF) treatment is associated with short-term transient increases in absolute lymphocyte counts (ALC), followed by a gradual decline to reach steady state by ~48 months. Changes in both ALC and lymphocyte subset counts (LSC) were reversible upon TOF discontinuation. Low ALC but not LSC were associated with an increased risk of serious infective episodes (SIEs) and herpes zoster (HZ). This data supported the treatment recommendations on ALC counts for starting and continuing therapy w...