Human monocyte heterogeneity: Interleukin 1 and prostaglandin E2 production by separate subsets

Abstract

Human peripheral blood monocytes were separated into four different subpopula-tions by means of a discontinuous bovine serum albumin gradient. Of the least dense population, 7% were present in fraction A, 11% in fraction B, 28% in fraction C and of the most dense, 34% were in fraction D. The rest (17%) of the recovered cells sedimented as a pellet, of which 95% were dead. The monocytes of fraction D (ϱ = ⩾ 1.075 kg/l) were major interleukin 1 (IL1) producers and their presence enhanced immunoglobulin synthesis in vitro. Fraction C (ϱ = ⩾ 1.070 kg/l) were the major prostaglandin E₂ (PGE₂) producers and demonstrated suppressor activity on in vitro IgG and IgM synthesis. Fractions A and B had minimal production of either IL1 or PGE₂ and lesser effects on the IgG and IgM synthesis. These data demonstrate functional heterogeneity of peripheral blood monocytes with respect to production of both IL1 and PGE₂ as well as accessory cells for immunoglobulin synthesis.