Direct correlation between diffusion of Loxosceles reclusa venom and extent of dermal inflammation

Hernan F. Gomez, Diann M. Greenfield, Mark J. Miller, Jeffrey S. Warren

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

Objectives: Envenomation by Loxosceles species (brown recluse) spiders results in large dermal inflammatory lesions. Venom-induced dermal inflammation occurs indirectly via soluble mediators of inflammation. This study aimed to explore whether the anatomic extent of dermonecrotic arachnidism is due to the cascade of soluble proinflammatory mediators elicited by venom deposited at the bite site, or due to diffusion of the venom per se. Methods: Three New Zealand white rabbits received intradermal L. reclusa venom (3-μg) injections in the flank. At the time of maximum dermal inflammation (24 hr), paired 4-mm dermal biopsies were obtained in 2-cm intervals extending 0 to 12 cm from the inoculation site. Normal dermal tissue was obtained from the opposite flank to serve as a negative control. One biopsy sample from each interval was homogenized and assayed for myeloperoxidase (MPO) activity and for the presence of venom via an enzyme immunoassay (EIA). The other paired dermal biopsy was sectioned, and examined for the presence of polymorphonuclear neutrophils (PMNs) by microscopy. Lesional areas were measured using digital images imported into imaging software. Results: Mean ± SD lesional diameter 24 hours post inoculation measured 9.18 ± 0.64 cm. Venom was detected in biopsies 0 to 10 cm from the injection site. As expected, the highest venom concentrations were measured at the inoculation site (4.28 ± 3.9 ng/4 mm). In addition, PMNs and MPO were detected up to 8 and 10 cm from the inoculation site, respectively. Neither PMNs nor MPO was detected in tissue absent of venom (kappa = 0.88, p < 0.001). Conclusions: Loxosceles venom diffuses from the envenomation site. The extent of dermal inflammation mirrors the extent of Loxosceles venom diffusion. This observation implies that the venom itself defines the extent and magnitude of tissue injury following Loxosceles envenomation.

Original languageEnglish
Pages (from-to)309-314
Number of pages6
JournalAcademic Emergency Medicine
Volume8
Issue number4
DOIs
StatePublished - 2001

Keywords

  • Arachnidism
  • Loxosceles
  • Spider
  • Venom

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