Monocyte subpopulations. Freshly isolated monocytes were obtained from noninfected donors and HTLV-1–infected donors. CD14 and CD16 expression was analyzed by flow cytometry. Representative dot plots showing (A) CD14 and CD16 (R1: CD14⁺CD16⁻, R2: CD14⁺CD16⁺) and (B) CD14 and CD56 (R1: CD14⁺CD56⁻, R2: CD14⁺CD56⁺) expression patterns. Data in bars (C) are expressed as percentage of positive cells. Data are mean ± SEM of 6 independent experiments. **Significantly different (P < .01) from control (CTR; CD14⁺CD16⁺).