Red blood cell lysis induced by the venom of the brown recluse spider: the role of sphingomyelinase D

Wound care of spider and snake envenomations

Venomous bites and stings are numerous but severe local tissue damage is uncommon. Venoms may be simple substances or complex mixtures of many poorly characterized components whose interactions are still not fully understood. The best studied example of a dermonecrotic venom is that produced by the brown recluse spider (Loxosceles reclusa). Rattlesnake envenomation also causes significant wound injuries. Many spider and snake envenomation management modalities are controversial and the evidence is mounting against the use of a number of these treatments.

[The use of exchange transfusion in severe human loxoscelism]

Foi utilizada a exsangüineotransfusão, associada à soroterapia heteróloga específica e alcalinização urinaria, em um caso de acidente loxoscélico humano na cidade de São Paulo. A indicação da exsangüineotransfusão foi a intensa hemólise associada à gravidade e o iminente risco de morte.

Plasma components are required for platelet activation by the toxin of Loxosceles reclusa

We have used a partially purified toxin from the venom of the brown recluse spider, Loxosceles reclusa, to study its effects on human platelets isolated from plasma proteins. This toxin, which produced skin necrosis in rabbits, contained sphingomyelinase D activity. The toxin induced platelet aggregation and secretion of [3H]serotonin in human plasma but not in buffer or in human neonate plasma. Ca2+ was required for the interaction of toxin, platelets, and plasma factor(s). The addition of C-reactive protein restored aggregation and serotonin release of platelets incubated in human neonate plasma. The ADP-degrading enzyme, apyrase, and the non-steroidal, anti-inflammatory drug, indomethacin, inhibited platelet aggregation, suggesting that ADP secreted from platelet storage granules and indomethacin-sensitive pathway(s) are involve in the toxin-induced human platelet activation (aggregation and serotonin release). Generation of platelet activating factor (PAF) from the platelet by brown recluse toxin is not likely since the PAF receptor antagonist, BN 52021, did not inhibit platelet aggregation induced by the brown recluse toxin.

Presumed arachnidism. A case report (in Connecticut)

An 8-year-old boy with multiple (up to 12) hemorrhagic and necrotic blisters was eventually diagnosed as being the victim of probable spider bites. Arachnidism, specifically loxoscelism (brown recluse spider bite), is unusual in the northeastern United States.

Immunotoxicology of brown recluse spider (Loxosceles reclusa) venom

A purified toxic protein from Loxosceles reclusa venom was assayed for its in vitro effects on the human immunological and blood clotting systems. The toxin caused inhibition of neutrophil chemotaxis, depletion of serum hemolytic complement, prolongation of the activated partial thromboplastin time and depletion of clotting factors XII, XI, IX and VIII by an average of 44% in human plasma. The prothrombin time of human plasma was also prolonged by 1.5-2.0 sec. No effect of the purified toxin was observed on microbicidal ability of neutrophils, the release of enzymes from neutrophils or the adherence of neutrophils to glass beads.

Interaction of brown recluse spider venom on cell membranes: the inciting mechanism?

The venom from the brown recluse spider, Loxosceles reclusa, contains one or more factors which produce skin necrosis. A dermonecrotic factor with sphingomyelinase D activity was purified from the spider's venom sacs which produced skin necrosis when injected intradermally in rabbits. Adsorption of the dermonecrotic activity occurred following incubation with isolated membranes from different cell types or different species in a dose-responsive fashion. Since injection of the complex in rabbits produced skin necrosis, a specific antibody that inhibits the dermonecrotic activity and sphingomyelinase activity was used to identify the venom fraction on the plasma membrane of erythrocytes with electron microscopy. Initiation of cutaneous inflammatory reaction may result from high-affinity interaction of a venom component in the brown recluse spider venom and cell membranes.

Isotachophoretic and immunological analysis of venoms from sea snakes (Laticauda semifasciata) and brown recluse spiders (Loxosceles reclusa) of different morphology, locality, sex, and developmental stages

Sea snake venom: The venom compositions of sea snakes, Laticauda semifasciata, with different scale patterns were analyzed by isotachophoresis. The comparison showed quantitative rather than qualitative differences. Similarly, L. semifasciata venoms of Philippine and Japanese origins differed only in the quantity of certain proteins. Spider venom: 3. Loxosceles reclusa venom apparatus extract is rich in neutral and acidic proteins but contains relatively small quantities of basic proteins. Differences in venom apparatus extract composition between nymph and adult (male or female) were detected by isotachophoresis. The extracts of male and female venom apparatus were very similar. Extracts of venom apparatus of spiders collected in locations separated by 100 miles were the same.

Enzymatic and hemolytic properties of brown recluse spider (Loxosceles reclusa) toxin and extracts of venom apparatus, cephalothorax and abdomen

Loxosceles reclusa venom apparatus extract, toxin, cephalothorax and abdomen extracts were tested for six activities. Protease, lipase, nonspecific hydrolase and direct hemolytic activities were found primarily in abdomen extracts while sphingomyelinase activity appeared predominantly in the toxin. Appreciable complement-mediated hemolysis was not observed.

Loxoscelism and necrotic arachnidism

The Brown recluse spider has emerged into a potent venomous creature. Loxoscelism and necrotic arachnidism is not an infrequent medical problem. Spiders other than L. reclusa are capable of inflicting painful and persisting necrotic wounds, however, management of the local cutaneous lesions are similar. Systemic complications of loxoscelism appear to be characteristic for spiders of the genus loxosceles. The authors review an indepth discussion of the spider, venom, diagnosis, clinical presentation, laboratory findings, treatment, and prevention. The literature on loxoscelism is contradictory because of the individuality of the reaction. Experience with many patients is the only guide to management of these cases.