Depletion of murine T cells by in vivo monoclonal antibody treatment is enhanced by adding an autologous anti-rat κ chain antibody

In vivo treatment with monoclonal antibodies can be used for elimination of various T lymphocyte subsets from peripheral lymphoid organs and blood and thereby be used both to analyze the role of different T cells in immunoregulation and for the treatment of experimental immunological diseases. However, one problem with this approach has been that not all monoclonal antibodies given in vivo eliminate their target cells. We now show in the murine system that the normally inefficiently depleting H129.19 (anti-CD4) and 53.6.7 (anti-CD8) antibodies can be used for efficient depletion of their respective target cells when combined with injection of a secondary mouse anti-rat kappa (MAR18.5) antibody. The efficacy of the depletion protocols was ascertained by double staining techniques and cytofluorometric analysis. It is suggested that the presently used sandwich method applying a homologous secondary monoclonal antibody may provide an alternative to class switching or other manipulations of primary antibodies in increasing the efficacy of in vivo antibody treatment.