Heterophilic antibodies in sera from individuals without loxoscelism cross-react with phospholipase D from the venom of Loxosceles and Sicarius spiders

Abstract

BackgroundLoxoscelism is a severe human envenomation caused by Loxosceles spider venom. To the best of our knowledge, no study has evaluated the presence of antibodies against Loxosceles venom in loxoscelism patients without treatment with antivenom immunotherapy. We perform a comparative analysis for the presence of antibodies capable of recognizing Loxosceles venom in a group of patients diagnosed with loxoscelism and in a group of people without loxoscelism.MethodsThe detection of L. laeta venom, Sicarius venom and recombinant phospholipases D from Loxosceles (PLDs) in sera from people with loxoscelism (Group 1) and from healthy people with no history of loxoscelism (Group 2) was evaluated using immuno-dot blot, indirect ELISA, and Western blot.ResultsWe found naturally heterophilic antibodies (IgG-type) in people without contact with Loxosceles spiders or any clinical history of loxoscelism. Either serum pools or single sera from Group 1 and Group 2 analyzed by dot blot tested positive for L. laeta venom. Indirect ELISA for venom recognition showed titles of 1:320 for Group 1 sera and 1:160 for Group 2 sera. Total IgG quantification showed no difference in sera from both groups. Pooled sera and purified IgG from sera of both groups revealed venom proteins between 25 and 32 kDa and the recombinant phospholipase D isoform 1 (rLlPLD1), specifically. Moreover, heterophile antibodies cross-react with PLDs from other Loxosceles species and the venom of Sicarius spider.ConclusionsPeople without contact with the spider venom produced heterophilic antibodies capable of generating a cross-reaction against the venom of L. laeta and Sicarius spiders. Their presence and possible interference should be considered in the development of immunoassays for Loxosceles venom detection.Electronic supplementary materialThe online version of this article (10.1186/s40409-018-0155-x) contains supplementary material, which is available to authorized users.

A Web of Coagulotoxicity: Failure of Antivenom to Neutralize the Destructive (Non-Clotting) Fibrinogenolytic Activity of Loxosceles and Sicarius Spider Venoms

“…This could be very important for S. terrosus bite treatment with Loxosceles-specific antivenom since there is no specific S. terrosus antivenom in production. However, a recent study does show cross-reactivity of heterophilic antibodies for loxoscelism between multiple Loxosceles species and Sicarius terrosus [33].…”

“…In addition to local symptoms, in nearly half of the cases, loxoscelism can cause severe systematic medical problems, including hematological disturbances and renal injury, which can progress to hemolysis, thrombocytopenia, shock, disseminated intravascular coagulation, acute renal failure, and even death [1,[4][5][6]. These hematological disturbances are most likely induced by metalloproteases, a few of which have been characterized such as Loxolysin A (20)(21)(22)(23)(24)(25)(26)(27)(28) and Loxolysin B (32)(33)(34)(35) found in L. intermedia venom [9]. Recent L. laeta venom gland transcriptomics identified multiple Loxosceles astacin-like metalloproteases (LALPs) within the 20 to 25 kDa range [10].…”

Brown recluse (L. rufescens) can bite in Northern Italy, too: first case report and review of the literature

“…Efforts to detect Loxosceles venom in situ are lacking and, what few methods exist, lack standardisation. Sandwich ELISA tests have shown some promise, with some being able to test values as small as 0.8 ng or 0.1 ng from the serum of inoculated mice and rabbits 19. An ELISA exists for L. reclusa and is likely functional for L. rufescens as well.…”

Systemic Loxoscelism, Less Frequent but More Deadly: The Involvement of Phospholipases D in the Pathophysiology of Envenomation

“…Although the mechanism of this hemolytic activity is not fully understood, these reported clinical events may be due to both direct and indirect activities, rendering erythrocytes more sensitive with the binding of phospholipases D, immunoglobulins, and proteins of complement systems, leading to lysis and clinical changes in patients. The hypothesis of antibody binding in phospholipases D-sensitized cells was supported by data showing that people who had never come into contact with these toxins, or had never been bitten by these spiders, naturally had antibodies that recognized these molecules [ 42 ].…”