Second Messenger-Induced Modulation of Thy-1 Antigen Expression: An Elisa Study Using Murine Thymic and Neuroblastoma Cells

Abstract

Freshly isolated cells of murine thymuses and in vitro cultured murine neuroblastoma cells were seeded into microplates, treated with either phorbol myristate acetate (PMA) or dibutyryl-cyclic adenosine monophosphate (DBcAMP), and then processed for enzyme imunoassay to analyze with G4 monoclonal antibody the expression of Thy-1.2 antigen epitope. Pretreatment of thymic cells with PMA resulted in little, if any, decrease of Thy-1 expression, while treatment of these cells with DBcAMP caused a significant down-modulation of the epitope. DBcAMP did not affect binding of another murine IgG antibody to the thymic cells. Modulation of the epitope on thymic cells caused by DBcAMP was dose-dependent with maximal effect seeen at the drug concentration of 10^-4M. However, at various doses of DBcAMP (10^-6 to 10^-4 M) we were unable to detect any significant shift of Thy-1 expression on neuroblastoma cells. Though mechanisms of the above phenomena need further elucidation, we conclude that cellular ELISA may provide a useful alternative to more commonly used cytofluorimetric studies for the analysis of immune cell-surface antigen expression and its pharmacological and physiological modulation.