In vitro studies of the suppression of delayed hypersensitivity by the induction of partial tolerance

Suppression of delayed hypersensitivity in vivo is correlated in vitro with the absence of macrophage migration inhibition in the presence of the antigen used to induce partial tolerance. The suppression of delayed hypersensitivity is antigen-specific in vivo as well as in vitro. The lymphocytes, and not the macrophages, are the cells involved in the induction of tolerance in terms of delayed hypersensitivity which is characterized by an absence of migratory factor activity.