Purified anti-human CD148

CD148, a receptor-like protein tyrosine phosphatase also known as human protein tyrosine phosphatase-eta (HPTP-eta) or density-enhanced protein tyrosine phosphatase-1 (DEP-1), is involved in signal transduction in leucocytes and is thought to contribute to mechanisms of cellular differentiation. In lymphoid organs, CD148 was found to be widely expressed on B and T cells, granulocytes, macrophages, certain dendritic cells as well as mature thymocytes. The cellular level of CD148 was increased after in vitro activation of peripheral blood leucocytes. CD148 as a leucocyte activation marker and may be involved in the regulation of T cell activation. Leucocytes expressing CD148 are significantly upregulated in inflamed tissues and that a subset of these cells co-expresses the activation marker CD25. In non-lymphoid tissues, CD148 was found to be present on many epithelial cell types with glandular and/or endocrine differentiation as well as on fibrocytes, melanocytes and Schwann cells. Among non-hematopoietic cells, CD148 is expressed by characteristic types of epithelial and non-epithelial cells. Downregulation of CD148 might promote dedifferentiation and autonomous growth of such cells in malignant tumors.