A ball cage for a constant velocity plunging joint which having an outer joint part with a internally cylindrical guiding face and an inner joint part with an outer spherical guiding face and torque transmitting balls held in the ball cage. One particularly preferred method uses methyl chloroformamide in a one-pot reaction at elevated temperatures to provide VNP40101M in high yield. The device also has a replaceable, on-board supply of cleanser. The identification by cytolytic T cells of the peptide analogueHLA complex may be used in diagnostics, or therapeutically.