Functional characteristics of histamine receptor-bearing mononuclear cells. II. Identification and characterization of two histamine-induced human lymphokines that inhibit lymphocyte migration.

Although functional histamine receptors have generally been restricted to those human T lymphocytes expressing suppressor cell functions, more recent evidence suggests that histamine receptor-bearing human T lymphocytes are functionally heterogeneous and capable of other immunomodulatory activities. Lymphocyte chemoattractant factor (LCF) is a cationic sialoprotein with an apparent m.w. of 56,000, whose production is limited to histamine-type 2 receptor-bearing human T cells. LCF is selectively chemokinetic for T lymphocytes, and presumably contributes to the recruitment of unsensitized effector lymphocytes at inflammatory sites. In addition to LCF, Sephadex G-100 gel filtration of histamine-induced lymphocyte supernatants revealed two regions of migration inhibitory activity for human blood T and rat splenic lymphocytes. These regions corresponded to m.w. of 70,000 to 80,000 (LyMIF75K) and 30,000 to 40,000 (LyMIF35K). LyMIF75K had a single pI of 7.5 to 8.0, and its biologic activity was sensitive to trypsin but not to neuraminidase or heat (56 degrees C). LyMIF35K had a single pI of 8.5 to 8.8, and its biologic activity was sensitive to neuraminidase and heat but not to trypsin. These LyMIFs therefore appeared to be distinct from one another and physicochemically different from other migration inhibitory lymphokines. All three lymphokine activities appeared within 4 hr of incubation. The minimum concentration of histamine required to stimulate production of the LyMIF was 10(-6) M. Lymphocytes that did not adhere to a histamine affinity matrix were unable to produce either LyMIF upon subsequent stimulation with histamine or concanavalin A (Con A). Lymphocytes incubated with histamine and diphenhydramine produced LCF but neither LyMIF, whereas cells incubated with histamine in the presence of cimetidine produced both LyMIF but not LCF. These data suggest that a subset of lymphocytes defined by the presence of histamine-type 1 receptors are capable of producing two distinct species of lymphocyte migration inhibitory activity. These cells may contribute to the immobilization of effector T lymphocytes chemokinetically attracted to certain inflammatory sites.