van Vollenhoven R, et al. - Investigators estimated the data to research over the short-, mid-, and long-term consequences of tofacitinib on lymphocytes as well as infection rates in subjects with rheumatoid arthritis (RA). They noted an increase in absolute lymphocyte counts (ALCs) with tofacitinib therapy vs pretreatment baseline initially with a further gradual decline to a steady state by about 48 months. They also found a decrease in CD4+ and CD8+ T cell count over long-term treatment. They observed a reverse in ALC and lymphocyte subset counts (LSCs) changes upon treatment cessation. An inclined risk of severe infections was noticed in cases with ALCs of <500 cells/mm³. No strong relation was reported between CD4+ T cell, CD8+ T cell, B cell, or natural killer cell counts and grave infection incidence rates. They also recorded a relationship between ALC and CD4+ or CD8+ T cell counts. They suggested the adequacy of monitoring of ALC alone for infection risk estimation in tofacitinib-treated patients with RA.