Proliferative responses of MCs obtained from three healthy donors (A, B, and C) against the panel of 42 peptides corresponding to the Rh D protein. In each case, all the peptides were tested on a single occasion, and the dashed line indicates the level of proliferation taken as representing a positive response (the higher of SI = 3 or CPM = 500). Positive control responses to the foreign recall antigen PPD are also shown.