Activity and Properties of Macrophage Migration Inhibitory Factor produced by Mixed Lymphocyte Cultures

THE macrophage migration test is an in vitro demonstration of delayed hypersensitivity. Supernatant fluids of sensitive lymphocytes cultured for 24 h in the presence of specific antigen contain migration inhibitory factor (MIF) that arrests the migration of macrophages of unsensitized animals in vitro¹,². In vivo, it induces delayed skin reactions³. The use of the macrophage migration test, based on differences of transplantation antigens in donor and recipient, to show histocompatibility has been suggested⁴. The test was also recommended as an indicator of immunological reactivity after organ transplantation, to demonstrate impending rejection⁵. It can demonstrate homograft sensitivity, for migration of peritoneal exudate cells (containing lymphocytes and macrophages) of CBA mice previously sensitized by grafts from A/Jax donors was inhibited when they were mixed with peritoneal exudate cells of the donor strain. However, histocompatibility was not demonstrated, for mixtures of peritoneal exudate cells of ungrafted CBA mice and A/Jax mice migrated regularly during the 24 h test⁶.