Slow reacting substances of anaphylaxis: Identification of leukotrienes C-1 and D from human and rat sources

Abstract

Slow reacting substance(s) of anaphylaxis (SRS-A) was isolated from both human (lung) and rat sources and compared with three synthetic SRS-As of known structureleukotrienes (LTs) C-1, C-2, and D. Reversed-phase liquid chromatography was used both as a final purification step and a means of comparison of biologically derived and synthetic substances. Two major peaks of SRS-A activity of both rat and human origin corresponded chromatographically with LTC-1 and LTD, respectively, and had equivalent specific activities on the guinea pig ileum. With guinea pig ileum, the specific activities (units/pmol) for synthetic leukotrienes and anaphylactic peaks were (mean -SEM): synthetic LTC-1, 1.93 -0.13; SRS-Arat peak I, 1.69 + 0.43; synthetic LTD, 6.10 i 1.15; SRS-Arat peak 11, 7.14 + 0.51; and SRS-AhU peak II, 1.90. Both synthetic LTC-1 and LTD and their SRS-A natural counterparts had a preferential contractile activity on guinea pig peripheral airway compared to central airways and were at least 200 times more active than histamine on peripheral airways on a molar basis. Leukotriene D is the major SRS-A of human lung and accounts for almost all of the biological activity. It likely is formed from leukotriene C-1 in vivo by an enzymic process of the well-known 'y-glutamyltransferase type.Although "slow reacting substance of anaphylaxis" (SRS-A) has been recognized as a putative major mediator of immediate hypersensitivity reactions for 40 years (1), only in the past decade have both proof of potency and evidence of chemical structure emerged. Brocklehurst (2) distinguished SRS-A from histamine in an anaphylactic perfusate by its contractile action on an (H-1) antihistamine-blocked guinea pig ileum wth a slow progression to maximal effect. Subsequent investigations established it to be a polar lipid (3, 4) with strong ultraviolet absorbance and possibly containing sulfur (4, 5). Cysteine was subsequently observed to augment generation of SRS-A (6) and a calcium ionophore was shown to stimulate production of nonanaphylactic slow-reacting substance (SRS) (7, 8) with incorporation of radiolabeled arachidonic acid as the lipid precursor (9, 10). Recently, an ionophore-stimulated SRS from mouse mastocytoma cells designated as leukotriene C-1 (11) (LTC-1) was identified as 5(S)-hydroxy-6(R)-S-glutathionyl-7,9-trans,11,14-cts-icosatetraenoic acid (II in Fig. 1) (12, 13) and was prepared in quantity by total synthesis.This communication reports the use of synthetic leukotrienes C-1 (13) and D (IV) (LTD) to standardize retention times on high-performance liquid chromatography (HPLC) (14,15) and to calculate the specific functional activities of SRS-A produced by an anaphylactic reaction in the rat peritoneal cavity or human lung. Additionally, naturally derived SRS-A components were compared with the synthetic leukotrienes in regard to differential and specific activities on the guinea pig tracheal and lung parenchymal muscle strips in vitro (14, 16), UV absorption, and enzymic oxidation. MATERIALS AND METHODSMaterials. ...

Allergen challenge of lung tissue from asthmatics elicits bronchial contraction that correlates with the release of leukotrienes C4, D4, and E4.

“…(20). After the structure elucidation of SRS-A (21,22), it was found that antigen challenge released LTC4 and LTD4 from passively sensitized human lung fragments (23) and that LTD4 was generated by immunological challenge of actively sensitized guinea pig lung (24). Since then, it has become evident that LTC4 is the primary SRS-A released and that further metabolism converts it into LTD4 and LTE4 (cf.…”

Pharmacotherapy of Asthma

“…Nedocromil is generally more effective at relieving asthma symptoms than cromolyn and may reduce the amount of inhaled steroids used in certain asthmatic patients. 18 While the efficacy of these agents in treating asthma appears to be less than the b 2 agonists and inhaled corticosteroids, both drugs have excellent track records of safety and few side effects due to their limited solubility.…”

LEUKOTRIENES C4 AND D4 INDUCE PROSTAGLANDIN AND THROMBOXANE RELEASE FROM RAT PERITONEAL MACROPHAGES

“…Both LTC and LTD have been shown to be produced by rat peritoneal macrophages when treated with a Ca2+ ionophore (Bach, Brashler, Hammarstrom & Samuelsson, 1980;Lewis, Austen, Drazen, Clark, Marfat & Corey, 1980). Furthermore, LTC has also been shown to be produced by mouse peritoneal macrophages in response to a phagocytotic stimulus (Rouzer, Scott, Cohn, Blackburn & Manning, 1980).…”

“…Both LTC and LTD had been shown to be produced by rat macrophages upon stimulation with a Ca21 ionophore (Bach et al, 1980Lewis et al, 1980 and a phagocytotic stimulus (Rouzer et al, 1980). Furthermore, the importance of endogenous leukotrienes in mediating biological functioning of immunoreactive cells is suggested by a recent study which showed that lysosomal enzyme release from neutrophils induced by arachidonic acid was blocked by an inhibitor of the lipoxygenase pathway (Walenga, Showell, Feinsten & Becker, 1980 been shown to induce degranulation (lysosyme release) in human neutrophils (Stenson & Parker, 1980).…”