The mouse monoclonal antibody BA5b recognizes an extracellular epitope of CD26, a 110 kDa type II transmembrane glycoprotein, which is a peptidase expressed on mature thymocytes, T cells (especially activated), B cells, NK cells and macrophages.
Dipeptidyl peptidase 4,CD26, also known as dipeptidyl peptidase IV (DPP-IV), is a homodimeric cell surface serine peptidase that degradates IFN-gamma-induced cytokines, acts as a T cell costimulatory molecule, and participates in multiple immunopathological roles in leukocyte homing and inflammation. Alterations in its peptidase activity are characteristic of malignant transformation. The enzymatic activity increases dramatically with tumour grade and severity. CD26 is expressed in various blood cell types, but also e.g. in cells that are histogenetically related to activated fibroblasts. Alterations in CD26 density have been reported on circulating monocytes and CD4+ T cells during rheumatoid arthritis and systemic lupus erythematosus.,DPP4, TP103, ADCP-2, ADABP