CCL5, produced by malignant T cells, attracts monocytes to the tumor microenvironment. (A) MyLa-conditioned media were used to attract monocytes in a 3-hour chemotaxis assay. An isotype control or neutralizing anti-CCL5 antibody was included in the assay, and spontaneous monocyte migration in response to media alone was subtracted from the data shown. Data shown are representative of at least 3 similarly performed experiments (mean ± SD). (B) Skin biopsies from CTCL patients (n = 10) were stained for CCL5. Two representative examples are shown, including an intraepidermal nest of malignant T cells (ie, Pautrier microabscess, indicated by [→]). (C) CCL5 was measured in plasma obtained from both normal donors (n = 24), and from patients with CTCL (n = 23) or PTCL (n = 29). Mean values ± 95% confidence intervals are shown; P < .001.