Faculty Bibliography

Allergic contract hypersensitivity (ACH)1 in young (3-5 mos.) and aged (16.18 mos.) BALB/c mice was evaluated by sensitizing the nape of the neck and subsequently challenging one ear with 1-chloro-2,4,6-trinitrobenzene (TNCB). Prior to sensitization, biopsy specimens of the contralateral unchallenged ears were obtained to determine the numbers of Ia+ Langerhans cells (LC) and mast cells (MC). Ear swelling responses, serum histamine levels, and histologic alterations of the challenged ears were evaluated in each age group at 0, 1.5, 4, 12 and 24 hrs. after challenge with TNCB. ACH was similar in young and aged mice during the first 12 hrs.; however, a significant difference in ear swelling was noted at 24 hrs. (38.0 .+-. 4.6 .times. 10-2 mm in young; 21.2 .+-. 2.0 in aged, p = 0.01.) There were no differences in MC number, degree of MC granulation, or serum histamine levels between young and aged mice at any time point. By 12 hrs., the inflammatory infiltrate in the ears of aged mice was slightly less intense and this difference became more marked at 24 hrs. At this time, the infiltrate consisted of neutrophils in young mice but continued to consist of mononuclear cells in the aged mice. Since the early ACH response in young and aged mice is similar, it is unlikely that decreased numbers of Ia+ LC in aged (449 .+-. 19 cells/mm2) as compared to young mice (720 .+-. 40) accounted for the decreased response at 24 hrs. We speculate that alterations in functional I cells in the age mice result in a diminished recruitment of neutrophils

Platelet activating factor was isolated from scales of psoriatic patients by the procedure of Bligh and Dyer and purified by silica gel thin layer chromatography. The purified PAF was digested with phospholipase C and the resulting diglyceride was derivatized into PFB ethers. The PAF-PFB ethers were analyzed using fused silica capillary chromatography-negative ion chemical ionization mass spectrometry. Different molecular species of PAF were identified by their negative ion mass spectra and by their elution time from the capillary column. All the molecular species had high abdundance (greater than 90%) of the molecular anion. 1-0-Hexadecyl-2-acetyl-GPC (16:0) was the major PAF species representing 51% of the total PAF. 17:0 and 18:1 were the next abundant species representing 15 and 16%, respectively. Several minor PAF molecular species were also present. The amount of each PAF molecular species was quantitated from 1-0-hexadecyl-2-2H3 acetyl-GPC used as the internal standard. Nanogram quantities of PAF were recovered from 100 mg of psoriatic scales. Significant amounts of lysoPAF were also present in these scales. The alkyl chain of the lysoPAF was compared with that of PAF.

An urticarial dermatosis after contact with the urticating hairs of the adult female Hylesia moth may occur by several mechanisms including the intradermal injection of inflammatory mediators through the urticating hairs. Extracts were prepared from whole moths, urticating hairs, and other moth parts. Each of these extracts was subjected to a radioenzyme assay for histamine. Histamine was present in extracts made from whole moths and from urticating hairs. Extracts made from other moth parts contained no histamine. Cutaneous wheals occurred after intradermal injections of histamine and various concentrations of Hylesia extract (HE) into the backs of cynomolgus monkeys. This whealing response was suppressed by pretreatment of the animals with diphenhydramine hydrochloride, but not by pretreatment with indomethacin. Histologic examinations showed a perivascular lymphocytic infiltrate around dilated capillaries without evidence of mast cell degranulation in HE-injected sites but not in controls. These findings provide evidence that histamine may be the mediator responsible for the urticarial lesions seen after contact with Hylesia moths