The 1F11/TSLPR monoclonal antibody specifically binds to Thymic Stromal Lymphopoietin Receptor (TSLPR). TSLPR is a member of the hematopoietin receptor superfamily and is also known as Cytokine Receptor-like Factor 2 (CRL2, CRLF2Y, CRLF2). The functional TSLPR complex consists of two subunits, TSLPR and the alpha subunit of the Interleukin-7 Receptor (IL-7Rα). Analysis of the TSLPR reveals sequence similarity with the common cytokine receptor gamma chain (γc; CD132). Functional TSLPRs are expressed by epithelial cells and a variety of hematopoietic cell types, including thymocytes, T cells, B cells, natural killer T cells, monocytes, macrophages, basophils, and dendritic cells (DC). Recent studies indicate that TSLP can activate multiple STAT (Signal Transducer and Activator of Transcription) signaling proteins. TSLP enhances the maturation and viability of DC. It strongly induces DC expression of the CD40 and CD80 costimulatory molecules and chemokines, e.g., TARC (Thymus and activation-regulated chemokine; CCL17) that can attract Th2 effector cells. TSLP supports B cell development. TSLP costimulates the proliferation of naïve T cells in the presence of mature DC. TSLP is also able to increase the sensitivity of T cell receptor-activated CD4+ T cells to low doses of IL-2. In the presence of TSLP, the acute myeloid leukemia-derived cell line, MUTZ-3, shows induced growth and reduced apoptosis. CRLF2 deregulated gene expression is thought to be involved in lymphoid transformation in B-cell precursor acute lymphoblastic leukemia. The 1F11/TSLPR antibody is reportedly a neutralizing antibody.