Relationship between³H-histamine uptake and H₂-receptors in the human promyelocytic leukemia cell line HL-60

Abstract

Association of³H-histamine (³H-H) with HL-60 cells was a time- and temperature-dependent process. At 37°C, the association of³H-H (50 fmole/10⁶ cells) was maximal and constant 60 min after the addition of HL-60 cells, while there is no significant radioactivity associated with cells incubated at 4°C during 120 min incubation. Under these conditions, the cell-associated radioactivity remains unchanged, even after a washout period and addition of large excess (10⁻³ M) of histamine, indicating an irreversible interaction between histamine and HL-60 cells. The interaction of³H-H with HL-60 cells depends on cell viability, cell concentration and was reduced by various metabolic inhibitors such as iodacetamide, dinitrophenol, sodium azide and ouabain. Histamine uptake by HL-60 cells was inhibited by a series of H₁, H₂ histamine agonists (impromidine, histamine, 4-MH, AET, PEA) and antagonists (cimetidine, oxmetidine, ranitidine, diphenhydramine), according to the following order of potencies: 1>H, 4-MH>AET>PEA and H, C>DPH. Among the histamine analogs tested (acidN-acetyl histamine, imidazole, acid imidazole acetic and histidine), only theN-acetyl histamine acid was able to inhibit³H-H uptake by HL-60 cells. Three antidepressant drugs (amitriptyline, imipramine, clomipramine) also antagonize³H-H uptake by HL-60 cells, but this effect was only observed at toxic concentrations (10⁻⁵ M and above) and was related to a loss of the cell viability. It was concluded that the promyelocytic leukemia cells HL-60 take up histamine by a specific energy-dependent mechanism, preferentially inhibitable by histamine H₂-receptor agonists and antagonists (H₂>H₁). Therefore, the uptake of³H-H by HL-60 cells accounts for an H₂-receptor-mediated process, consistent with the pharmacological specificity of the histamine H₂-receptor linked to the cAMP generating system in this cell line.