For analysis of cytokine production, T cells were stimulated with either control medium or 50 ng/ml PMA and 750 ng/ml ionomycin plus 10 g/ml Brefeldin A (Calbiochem) for four hours. of IL-4 and higher amounts of IFN. Moreover, there was a marked lack of infections in alemtuzumab-treated L-CTCL patients despite the total absence of T cells in blood, suggesting that skin resident TEM can protect the skin from pathogens even in the absence of T cell recruitment from your circulation. Together, these data suggest that alemtuzumab may treat refractory L-CTCL without severely compromising the immune response to contamination by depleting circulating TCM but sparing the skin resident TEM that provide local immune protection of the skin. Introduction Cutaneous T cell lymphomas (CTCL) are a heterogeneous group of non-Hodgkins lymphomas that represent malignancies of skin homing T cells (1). CTCL encompasses both skin limited variants such as mycosis fungoides (MF) and leukemic forms of the disease (L-CTCL) including Szary syndrome. In MF, malignant cells are confined to fixed skin lesions and many patients have indolent disease with a normal life expectancy (2). Patients with progressive MF can develop skin tumors and lymph node involvement, but blood involvement is usually rare. L-CTCL patients often present with lymphadenopathy and diffuse erythema: Malignant T cells in these patients are frequently present in the blood, skin, and lymph nodes. L-CTCL is usually often refractory to multiple therapies; patients have a median survival of 3 years and most pass away from infections. Hematopoietic stem cell transplantation is the only potentially definitive remedy for both advanced MF and L-CTCL (3). We statement here findings that low dose alemtuzumab (Campath), a T cell-depleting antibody directed against CD52, can induce clinical responses in all patients and total remission in 50% of patients with refractory L-CTCL. Although early-stage MF and L-CTCL have previously been Rabbit Polyclonal to PML considered to be points in a disease continuum, differing molecular profiles and responses to therapy suggest these disorders may arise from two unique T cell subsets (2, 4C6). We have found that the malignant T cells in L-CTCL are L-selectin/CCR7+ and have a central memory T cell (TCM) phenotype, whereas the malignant T cells in MF have a phenotype of skin resident effector memory T cells (TEM) (6). In mouse models of T cell memory, TCM and TEM have unique migratory patterns and effector potential but these issues have not been analyzed Bexarotene (LGD1069) in human beings. We present here findings that human cutaneous TCM recirculate into blood, whereas TEM are a non-recirculating skin resident population. Moreover we provide evidence from our treated patients that cutaneous TEM can provide immunologic protection against skin infection even in the absence of TCM. Results Malignant T cells have a TCM phenotype in L-CTCL and a TEM phenotype in MF Clonal malignant T cells can be identified in some CTCL patients by staining with commercially available antibodies to TCR V subfamilies. By identifying the malignant T cell clone, experts can assess Bexarotene (LGD1069) disease burden and monitor for recurrence (7). As reported previously, clonal malignant T cells from both the blood and skin of L-CTCL patients co-expressed L-selectin and CCR7, a phenotype characteristic of TCM (6)(Fig. 1A). Greater than 90% of malignant T cells in blood expressed CCR4, but individual populations of CLA? and CLA+ clonal T cells existed in the blood of most patients. However, malignant T cells expressing CLA were the predominant populace observed in lesional skin (Fig. 1A, Table S1). Open in a separate windows Fig. 1 Low dose alemtuzumab is effective in the treatment of L-CTCL, a malignancy of TCM, but is usually ineffective in MF, a malignancy of TEM. (A) Clonal malignant T cells isolated from your blood and lesional skin of patients with L-CTCL Bexarotene (LGD1069) co-expressed L-selectin and CCR7, a phenotype consistent with TCM. A subset of circulating malignant cells also expressed the skin homing addressins CCR4 and CLA. Malignant T cells co-expressing CCR4 and CLA predominated in skin lesions. A representative individual is usually shown; expression of CLA and CCR4 was confirmed in 5 additional L-CTCL patients with identifiable T cell clones (Table S1). (B) High side/forward scatter can be used to identify the malignant T cells in CTCL. High scatter cells isolated from your fixed skin lesions of MF expressed skin homing addressins CLA and CCR4 but lacked expression of L-selectin and CCR7, consistent with the claim that MF is usually a malignancy of skin resident effector memory T cells (TEM). Findings have been replicated in.