Human T cell subsets differ in their ability to migrate in vitro and to produce T cell migration inhibitory factor.

The spontaneous migration in vitro, production of T cell migration inhibitory factor (TIF) and the response to TIF of OKT4+ and OKT8+ human T cell subsets were studied. The OKT4+ lymphocytes migrated far better than the OKT8+ cells although the movement of both subsets was comparably inhibited by TIF. The OKT8+ subset was found to be a major source of TIF, while OKT4+ cells were responsible for macrophage migration inhibitory factor (MIF) production. The implications of lymphokine production by OKT8+ cells for the regulation of inflammatory responses are discussed.