Increase of FoxP3, CTLA4, and GITR expression on naive CD4⁺CD25^high T_reg cells from MGUS and MM patients.FoxP3, CD62L, CTLA4, and GITR expression of naive CD4⁺CD25^highT cells in PB of healthy donors, MGUS patients, as well as PB or BM of MM patients coexpressing CD45RA and CCR7 by multicolor flow cytometry. Results are expressed as percent of CCR7⁺CD45RA⁺ CD4⁺CD25^high T cells. Error bars represent SD. (A) Intracellular FoxP3 (*MGUS and PB, P < .05, Student t test), (B) extracellular CD62L, (C) intracellular CTLA4 (*MGUS, PB, and BM, P < .01, Student t test), (D) intracellular GITR (*MGUS and PB, P < .05, Student t test). Control indicates peripheral blood from healthy individuals (n = 13); MGUS, peripheral blood from MGUS patients (n = 8); PB, peripheral blood from MM patients (n = 7); BM, bone marrow from MM patients (n = 6); and n.d., not done.