Chemoattractants induce rapid release of the interleukin 1 type II decoy receptor in human polymorphonuclear cells.
Molecules representative of different classes of chemotactic agents, including formyl-Met-Leu-Phe (FMLP), C5a, leukotriene B4, platelet-activating factor, and interleukin (IL)-8, caused a rapid reduction in the IL-1 binding capacity by human polymorphonuclear leukocytes (PMN), a cell type expressing predominantly the IL-1 type II decoy receptor (IL-1 decoy RII). N-t-Boc-Met-Leu-Phe, an antagonist for the FMLP receptor, inhibited the loss of IL-1 binding capacity induced by FMLP. Monocyte chemotactic protein 1, a chemokine related to IL-8 but inactive on PMN, had no effect on IL-1 binding in this cell type. FMLP was selected for further detailed analysis of chemoattractant-induced loss of IL-1 binding by PMN. The action of FMLP was rapid, reaching 50% of its maximum (80%) at 30 s, the earliest measurable time point, and plateauing between 10 and 30 min. Dose-response analysis revealed that maximal reduction of IL-1 binding was reached at FMLP concentrations that were also optimal for chemotaxis (50% effective dose = 5 x 10(-9) M). The loss of IL-1 binding capacity caused by FMLP was determined by a reduction in receptor number with no change in their affinity. The effect of FMLP on IL-1 receptor (IL-1R) was selective in that the PMN surface structures IL-8R, CD16, CD18, and major histocompatibility complex class I antigens were unaffected under these conditions. Loss of surface IL-1R was not due to an augumented rate of internalization. FMLP caused rapid release of a 45-kD IL-1-binding molecule identified as the IL-1 decoy RII. After FMLP-induced release, PMN reexpressed newly synthesized receptors, reaching basal levels by 4 h. FMLP-induced release of the IL-1 decoy RII did not impair the responsiveness of PMN to IL-1 in terms of promotion of survival and cytokine production. FMLP-induced release of the IL-1 decoy RII was unaffected by protein synthesis inhibitors, was blocked by certain protease inhibitors, and was mimicked by agents (the Ca++ ionophore A23187 and phorbol myristate acetate) that recapitulate elements in the signal transduction pathway of chemoattractant receptors. The time frame and concentration range of chemoattractant-induced rapid release of the IL-1 decoy RII are consistent with the view that IL-1 decoy RII release is an early event in the multistep process of leukocyte recruitment.(ABSTRACT TRUNCATED AT 400 WORDS)
Colotta
F
F
Istituto di Ricerche Farmacologiche Mario Negri, Centro Daniela e Catullo Borgomainerio, Milano, Italy.
Orlando
S
S
Fadlon
E J
EJ
Sozzani
S
S
Matteucci
C
C
Mantovani
A
A
D000595:Amino Acid Sequence; D000001:Calcimycin / Q000494:pharmacology; D002630:Chemotactic Factors / Q000494:pharmacology*; D002634:Chemotaxis, Leukocyte / Q000187:drug effects / Q000502:physiology*; D015936:Complement C5a / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000378:metabolism / Q000494:pharmacology; D016209:Interleukin-8 / Q000494:pharmacology; D007975:Leukotriene B4 / Q000494:pharmacology; D008969:Molecular Sequence Data; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D009842:Oligopeptides / Q000494:pharmacology; D010972:Platelet Activating Factor / Q000494:pharmacology; D017472:Receptors, Interleukin-1 / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D002630:Chemotactic Factors; D007375:Interleukin-1; D016209:Interleukin-8; D009842:Oligopeptides; D010972:Platelet Activating Factor; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins; D007975:Leukotriene B4; D000001:Calcimycin; D009240:N-Formylmethionine Leucyl-Phenylalanine; D015936:Complement C5a; D013755:Tetradecanoylphorbol Acetate