Proliferative response of a representative COP-reactive and a MBP-reactive TCL. TCL were stimulated with COP, MBP, various control antigens (MOG, S-100β, and TT), or the T-cell mitogen phytohemagglutinin (PHA). There was no detectable cross-reaction between COP and MBP at the level of proliferation. Ag, antigen.