CD95 ligand (CD95L) immunohistochemistry: a critical study on 12 antibodies

In recent years, some studies on the expression of CD95(Fas/ APO-1) ligand (CD95L) in tissues or cells raised concerns about the specificity of the an tibodies used, We therefore tested 12 CD95L antibodies for their reliabilit y in immunocyto/ histochemistry by (i) staining CD95L-transfected and contr ol CV-1/EBNA cells and (ii) comparing staining patterns in immunohistochemi cally labeled tissue sections with the localization of CD95L+ cells in in s itu hybridization, While G247-4, NOK-1, NOK-2, 4H9, and MIKE-1 stained CD95 L-transfected cells and did not significantly bind to controls, G247-4 was the only antibody giving satisfying signals in tissue sections perfectly ma tching the distribution of CD95L+ cells by in situ hybridization. MAb 33, C -20, and N-20 comparably stained both transfected and control cells and sho wed considerable background or falsely positive staining in sections. MIKE- 5, 8B8, A11, and 4A5 did not or only very faintly bind to either cells and, thus, were not tested on sections. We conclude that G247-4 is the only tes ted antibody that is recommendable for immunohistochemistry.