Evidence for Histamine in the Urticating Hairs of Hylesia Moths* Scott M . Dinehart, M.D., Joseph L. Jorizzo, M .D., Nicholas A. Soter, M .D., Nopadon Noppakun, M.D. , William R . Voss, D.V.M.,t James A . Hokanson, Ph.D., and Edgar B. Smith, M.D. Department of Dermatology (S MD, JLJ , NN. EBS). the Animal Care Center (WRV). and the Biostatisti ca l Component. Cancer Center UAH), The University of Texas Medical Branch, Galveston, Texas; and Department of Dermatology (NAS). New York University School of Medicine, New York, New York. U.S.A. An urticarial dermatosis after contact with the urtica tin g les ia extract (HE) into the backs of cynomolgus monkeys. hairs of the adult female Hyles ia moth may occur by several This whealin g res ponse was suppressed by pretreatment of mech a nisms including the intradermal inj ection of inflam­ the animals with diphenhydraminc hydrochloride, but not matory mcdiators through the urticatin g hairs. Extracts by pretrea tment with indometha ci n. Histologic examina­ were prepared from whole moths, urticatin g hairs, and tions showed a perivascul ar lymphocytic infiltrate around other moth parts. Each of these extracts was subjected to dilated capillaries without evidence of mas t cell degranu.:. a radioenzy mc assay for histamine. Histamine was present \ation in H E-injected sites but not in controls. These find­ in extracts made from whole moths and from urtica ting in gs provide evidence that histamine may be the mediator hairs. Extracts madc from other moth parts contained no res ponsible for the urticarial lesions seen after contact with histamin e. C utaneous wheals occurred after intradermal Hyles ia moths. ) I/1l1 est Dernwtol 88:691- 693, 1987 injections of histamine and various concentrations of Hy- ermatitis occurring after contact with urtica ting hairs portunity to exa mine crew members from an oil tanker that was of th e adult female Hyles ia moth has been well doc­ infested by swarms of Hylesia moths at the port of Caripito, umented [1-3]. The eruption is pruritic, occurs on Venezuela 11] . The presence of a predominantly urtica ri al eruption exposed surfaces, and is commonl y urtica ri al. The in most of the crew suggested the possibl e role of hista mine as a condition is generall y unresponsive to various top­ toxic substance contained in the urtica ting hairs. Dica l and systemic medica ti ons; however, spontaneous resolution Meth ods for identifyin g and charac terizin g mediators of cu­ occu rs in about one week, provided contact with moths or moth taneous inflammation have been described [4-6]. The present pa rts is discontinued. study examines the actions of extracts of Hylesia mo ths in monkey Several mechanisms for the producti on of the dermatitis have skin over a wide dose range in the presence and abse nce of an been proposed and include intracutaneous injection of toxic sub­ H I-receptor antagonist, diphenhydramine hydrochloride, and the stan ce(s) through the holl ow urticating hairs, direct irritant effect cyclooxygenase inhibitor, indomethacin , to indirectly assess the of the h airs, and hypersensitivity to insect antigen(s) [1 ,31. More presence of mediator ac tivity. Using a radioenzy me assay, we than one mechanism may be involved. examined extracts of whole moths, w ings and legs, and urticatin g Dern1atitis produced by Hylesia moths is frequent in Latin hairs for th e presence of hista mine. Am.erica but rare in the United States. We recently had the op- MATERIALS AND METHODS Subjects Indirect mediator studies employed healthy ad ult cy­ Manuscript received August 19. 1986; accepted for publication No­ nomolgus monkeys (Macaca JasciCil laris). ve mber 25, 1986. * Read before the Southern Region of The Society fo r In vesti gative Intracutaneous Injections After sedation w ith i. m. ketamine Dennatology. Inc., New O rlea ns, Louisiana, February 7. 1986 and at the Annual Meetin g of The Society for In ves ti gative Dermatology, In c.. hydrochl o ride (Ketalar®) at a dose of 15 mg/ kg, the backs of 4 Washington, D.C., May 3. 1986. monkeys were shaved, washed with isopropyl alcohol, and then tPresent address: University of Texas System Cancer Center. Science inj ected intradermall y usin g a 30-ga uge needle w ith 50 J.Ll of di­ Pa rk, Veterinary Resources Division, Route 2, Box 151-B I. Bastrop, lutions of Hylesia extract (HE), phosphate-buffered saline, pH 7.6 Texas 78602. (PBS), hi stamine, and buffer consisting of 1.0 M sodium chl o ride Reprint requests to: Scott Dinehart, M. D .. Department of Dermatol­ and 25% ethylene glycol (EG-N aCl) . Inj ections w ere ca rried out ogy, T h e University of Texas Med ica l Branch, Ga lveston. Texas 77550. at 2.5-min intervals in a double-blind random fashion according Abbreviations: to our published method [5 ,6]. Two perpendicular diameters of ANOVA: anal ysis o f variance th e wheal, including the longest axis and ignorin g small pseu­ EG-N aCI: buffer consisting of 1. 0 M sodium chl oride and 25% dopodia, were measured between 5 and 7 min, w hen the wheal ethylene glycol HE: /-/),l csia extract was fully developed. The size of the w heal was given as th.e mean K-W: Kruskal-Walli s of the maximal diameters. Wheals measuring less than 7.5 mm PBS: phosphate-buffe red sa line, pH = 7.6 median diameter were not considered a response, as this was the 0022-202X/87/S03.50 Copyright © 1987 by The Society for In vestigati ve Dermatology. In c. 691 692 DINEHART ET AL THE JOURNAL OF INVEST IGATIVE DERMATOLOGY mean diameter of the injection bleb. The ambient temperature Statistical Analysis Analysis of variance (ANOVA) followed was 22-24°C. Evidence for delayed hypersensitivity at the sites by contrast analysis were the primary statistical methods em­ of cutaneous injection was assessed at 48 and 96 h. ployed. The Statistical Package for the Social Sciences was used Pharmacologic Treatment Baseline dose response curves of for all computations [1 0]. w hea l response were obtain ed after injections as described above RESULTS on day 1. All 4 monkeys received 3.0 mg/kg of th e H ,-receptor blocker diphenh ydramine hydrochloride i.m. the morning of the Local Effects in Monkey Skin Results of HE monkey injec­ experiment on day 3. Four hours later, another 1.5 mg/kg i.m. tion experiments plotted on log 2 paper are summarized in Fig dose was given. T he experiment began 2 h after the second dose 1. Wheals produced by vehicle control injections approximated and lasted 45 min to 1 h. All 4 monkeys received 4.0 mg/kg of 8 mm, which was about the size of an injection bleb. Histamin e indo methacin orally the morning of the experiment on day 5. injection w hea ls approached 12 mm. As the concentration of HE Four hours later, another 4.0 mg/kg oral dose was given. The was increased, wheal size generall y increased. After pretreatment experiment began 2 h after the second dose and lasted 45 min to with diphenhydramine hydrochloride, wheal formation was gen­ 1 h. Dosages of diphenhydramine hydrochloride and indometh­ erally suppressed to the levels of control injections. For day 1 (no acin were given in accordance with guidelines for nonhuman pharmacologic pretreatment) a one-way ANOVA was performed primates. to compare PBS and EG-NaCI to the 4 dilutions of HE. Because these res ults were stati sticall y significant (F = 8.13, P < 0.01), Solutions Appropriate dilutions of injected substances were PBS and EG-NaCI were then compared with all the dilutions made up freshly and sterili zed by an acryli c copolymer membrane grouped together. As both the Bartlett-Box F and Cochran's C filter 0.20 J.Lm (Gelman Acrodisc@ no. 4192, Gelman Scientific, were not signifi cant, the pooled variance estimate was used. The Ann Arbor, Michi gan). In each experiment, response to HE di­ contrast analysis was statistically signifi cant (t = 3.37, P < 0.01). luted 1:1, 1 :2, 1 :4, and 1:16 with PBS was assessed. The response These two analyses suggest that PBS and EG-NaCI produce val­ to 0.05 mg histamine/50 J.LI was a positive control. The res ponses ues different than vehicle containing any amount of HE. Phos­ to 50 J.LI of PBS and EG-NaCI were negative controls. All so­ phate-buffered saline and EG-NaCI were compared w ith hista­ lutions were measured at pH 7.5-7.6. mine of day 1. These results were statistically signifi ca nt (t = The HE had been prepared as follows: the bodies of each of 48.8, P < 0.01). These results were also consistent with the more 10 adult moths, the separated hairs, and the wings of 1 moth conservative Kruskal-Wallis (K-W) procedure. For PBS and EG­ were weighed and minced in plastic tubes containing 1.0 ml of N aCI vs dilutions of HE, the K- W chi-square was 13.0 (p < 0.01) EG-NaCI [7]. After boiling for 10 min, the tubes were sedimented and for comparison of PBS with histamine the K-W chi-square at 400 g for 10 min, and the supernatant fractions were frozen at was 5.4 (p < 0.02) . -20°C. The initial two-way ANOV A across' days and dilutions indi­ Assessment of.Histamine Duplicate aliquots were assessed for cated both significant main (F = 17.5, P < 0.01) and interraction th eir histamine content with a radioenzyme assay [8,9].