Analysis of the Leukotriene D₄ Receptor in the Granulation Tissue of Allergic Inflammation in Rats.

Hirasawa, Noriyasu; Hoshi, Tomonori; Kudoh, Michiko; Mue, Suetsugu; Tsurufuji, Susumu; Watanabe, Masako; Ohuchi, Kazuo

Leukotriene (LT) D4 receptor in the granulation tissue formed in the air pouch-type allergic inflammation model in rats was analyzed. Membrane preparation of the granulation tissue obtained 3-9 days after the antigen challenge has specific binding sites of [3H]LTD4. Scatchard analysis showed that the affinity (Kd) and the density (Bmax) were not changed among the granulation tissue obtained 3-9 days after the antigen challenge. The Kd value in the granulation tissue (0.90 ± 0.12 nM) was close to that in the rat lung (1.00 ± 0.24 nM) and the guinea pig lung (0.86 nM). On the other hand, Bmax (62 ± 8 fmol/mg protein) in the granulation tissue was higher than that in the rat lung (21 ± 4 fmol/mg protein) but was far less than that in the guinea pig lung (405 fmol/mg protein). LTC4 and LTE4 inhibited the binding of [3H]LTD4 to the membrane preparation of the granulation tissue in a concentration-dependent manner. IC50 of LTC4 and LTE4 were 1 × 10--7 and 2 × 10--7M, respectively. A guanine nucleotide, guanyl-5'-yl-imido-diphosphate (GppNHp), reduced [3H]LTD4 binding to the membrane preparation of the granulation tissue suggesting that LTD4 receptors in the granulation tissue are associated with G proteins. These results indicate that LTD4 binding sites in the granulation tissue are high affinity receptors for LTD4. A possible role of LTD4 in the recurrence of allergic inflammation in the chronic phase is discussed. Copyright © 1992 S. Karger AG, Basel

International Archives of Allergy & Immunology, 1992, Vol 99, Issue 1, p107

1018-2438

Academic Journal

10.1159/000236342