Reduction of CD4⁺ T cells and HTLV-1 viral load following denileukin diftitox and alemtuzumab. Results are depicted as HTLV-1 copies per microgram of DNA relative to time (♦). The number of CD4⁺ cells per cubic millimeter was determined by FACS analysis using antihuman CD4 antibody. Results are depicted as CD4⁺ cells per cubic millimeter relative to time (•). Denileukin diftitox and alemtuzumab treatment periods are indicated as bars above the line graphs.