(+-)-Thalidomide-d4 is intended for use as an internal standard for the quantification of (+-)-thalidomide (Item No. 14610) by GC- or LC-MS. (+-)-Thalidomide is an immunomodulatory compound with diverse biological activities, including anticancer, anti-inflammatory, and teratogenic properties.{54394,54393,54392} It prevents polymorphonuclear leukocyte (PMN) chemotaxis when used at concentrations of 1, 10, and 100 µg/ml.{54394} (+-)-Thalidomide increases IL-2-induced proliferation and IFN-y production in primary human T cells in vitro.{54393} It enhances natural killer (NK) cell-mediated cytotoxicity in MM.1S multiple myeloma cells.{54392} Thalidomide (4 mg/animal) reduces lung IL-6, TGF-B, VEGF, angiopoietin-1, angiopoietin-2, and collagen type Ia1 expression, inhibits pulmonary angiogenesis, and attenuates fibrosis in a mouse model of bleomycin-induced pulmonary fibrosis.{54395} It induces apoptosis in primary human embryonic fibroblasts (EC50 = 8.9 µM) and induces limb and eye defects in chicken embryos (EC50 = 50 µg/kg egg weight).{54396} Formulations containing thalidomide have been used in the treatment of multiple myeloma and erythema nodosum leprosum (ENL) in non-pregnant individuals.