Lenalidomide is an effective therapeutic agent for multiple myeloma that exhibits immunomodulatory properties including the activation of T and NK cells. to a myeloma-specific tumor vaccine. test was used for comparison, and values of 0.05 were considered as significant. Results Lenalidomide promotes the Th1 phenotype We examined the effects of lenalidomide on T-cell polarization following ligation of the costimulatory complex with antibodies directed against CD3 and CD28. The addition of lenalidomide to anti-CD3/CD28 stimulated T cells obtained from normal donors resulted in a twofold increase in the percentage of CD4 + and CD8 Rabbit polyclonal to ALKBH1 + T cells expressing IFN- as compared to T cells stimulated with anti-CD3/CD28 alone (= 5, = 0.06 and = 0.02 for CD4 + and CD8 + , respectively). Exposure to lenalidomide resulted in a similar increase in the percentage of T cells expressing IFN- in CD8 + cells derived from patients with multiple myeloma (= 5, = 0.01, Fig. 1). In contrast, intracellular production of the Th2 cytokine, IL-10, remained at baseline low levels after exposure to lenalidomide (data not shown). These studies demonstrate that lenalidomide induces polarization of T cells derived from myeloma patients toward the inflammatory Th1 phenotype. Fig. 1 Lenalidomide induces T-cell polarization toward a Th1 phenotype in T cells obtained from MM patients. a Proportion of CD4 + and CD8 + T cells expressing intracellular IFN- after ligation of the co-stimulatory complex with anti-CD3 and anti-CD28 … Lenalidomide blunts regulatory T-cell expansion Regulatory T cells undergo expansion in response to stimuli, such as anti-CD3/CD28, that promote T-cell activation to Volasertib maintain immunologic equilibrium and protect against auto-immunity. However, exposure to lenalidomide during the period of anti-CD3/CD28-mediated stimulation of T cells from normal donors resulted in a decrease in Volasertib the percentage of regulatory T cells from 6.88 to 3.13 (= 8, = 0.05). Similarly, the percentage of regulatory T cells isolated from patients with MM also decreased in the presence of lenalidomide (1.8 as compared to 4.85, = 5, = 0.04, Fig. 2), indicating that lenalidomide attenuates regulatory T-cell expansion. Fig. 2 Lenalidomide blunts regulatory T-cell expansion. a Representative plot showing a decrease of the CD25 +/ FoxP3 + population in the CD4 + gate after 4 day culture in media containing 1 M lenalidomide compared with a control media, a MM patient … Lenalidomide suppresses T-cell expression of PD-1 The PD-1/PDL-1 pathway is upregulated in the setting of malignancy and chronic infection where it has been shown to promote an exhausted T-cell phenotype facilitating tumor tolerance and immunologic escape. In the present studies, PD-1 expression was significantly increased on T cells obtained from MM patients compared to healthy controls (30 % as opposed to 7.6 %, = 0.001, Fig. 3a). Notably, exposure to lenalidomide decreased PD-1 expression on CD4 + T cells from both healthy volunteers (from 7.62 to 3.75 %, = 7, = 0.03) and MM patients (from 29.8 to 22.3 %, = 5, = 0.05, Fig. 3a, b). Fig. 3 PD-1 expression is increased on T cells in patients with MM and is downregulated by lenalidomide. a Mean expression of PD-1 on resting CD4 + T cells in patients with MM and healthy controls after 4 day exposure to 1 M lenalidomide compared to … Lenalidomide augments T-cell proliferation in response to stimulation with allogeneic DCs We next examined Volasertib the effect of lenalidomide on the in vitro response of T cells to stimulation with allogeneic DCs. T cells were co-cultured with allogeneic DCs in a standard MLR in control media (Supplemental Fig. 1, condition A) and in media with lenalidomide (Supplemental Volasertib Fig. 1, condition B). DC-mediated stimulation of T cells in the presence of lenalidomide resulted in a twofold increase in proliferation as compared to T cells co-cultured with allogeneic DCs in control media (= 3, = 0.015). To determine whether this increase in proliferation is mediated by lenalidomide effects on T cells or DCs, the populations of T cells and the antigen-presenting DCs, respectively,.