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Interaction of Loxosceles laeta venom components with red cell membranes
SUA
INTERACTION OF LOXOSCELES LAETA VENOM COMPONENTS WITH RED CELL MEMBRANES
Suarez,G ., Schenone .H ., Raventos,C .,Rojas,F.,Biggemann,U . and Contreras ,G . Albert Einstein College of Medicine,Bronx, New York 10461, U.S .A . and University of Chile, Santiago, Chile .
The bite of the spider Loxoscels laeta causes severe lesions in man and other mammals . The failure to detect in the venom gland extracts enzymatiL~ activities,such as phospholipase (Schenone and Suarez,1978)which could help understand the mechanism of action and the demons tration of a cytopathic effect of partially purified venom on human cells in culture(Suarez et a1 .,1976)led us to investigate the influence of the venom on two membrane-related processes : the complement-induced hemolysis and influenza virus-promoted hemagglutination . Unfractionated venom gland extracts as well as well as active fractions prepared as described by Suarez et a1 . ,1971, inhibited the hemolysis mediated obtained from various animal
by the complment system
sources, including Rattus norvegicus, a species resistant to
the venom .The extent of inhibition is dose-dependent and can be complete for guinea pig complement .The inhibitory effect,which is heat-sensitive,can be reversed by increasing the concentration of complement . Venom extracts also inhibited influenza virus-induced hemagglutination .The inhibition by the venom was dose-dependent and can be total . It was not possible to detect in the venom extract any neuraminidase activity which could destroy the virus receptor on the membrane . In order to obtain a direct evidence of the interaction of the venom with the cell membrane, antibodies against components of venom extracts were prepared in the rabbit .The antibodies were conjugated with fluorescein isothiocyanate (FITC) .Sheep RBC were incubated with partially purified venom,washed three times with saline and then incubated with FITClabelled antibody .Upon examination on the fluorescence microscope the RBC treated as described showed halos of fluorescence which were absent in control samples . Finally, sheep RBC incubated with crude venom and washed three times with saline produced lesiones in the skin of the rabbit which were undistinguishable from those produced by the direct inoculation of partially purified extracts . The results described provide strong evidence that venom components of L . l aeta bind to the RBC membrane at specific sites which are required for the operation of the complement system as well
as for the attachment of influenza virus .
SCHENONE,H . and SUAREZ,G .(1978) Handbook of Experimental SUAREZ,G .,CONTRERAS,G . and SCHENONE,H .
Pharmacology _48, 247 .
(1976) Toxicon _14, 335 .
SUAREZ,G ., SCHENONE,H . and SOCIAS,T . (1971) Toxicon 9,291 .
~80
INTERACTION OF LOXOSCELES LAETA VENOM COMPONENTS WITH RED CELL MEMBRANES
Suarez,G ., Schenone .H ., Raventos,C .,Rojas,F.,Biggemann,U . and Contreras ,G . Albert Einstein College of Medicine,Bronx, New York 10461, U.S .A . and University of Chile, Santiago, Chile .
The bite of the spider Loxoscels laeta causes severe lesions in man and other mammals . The failure to detect in the venom gland extracts enzymatiL~ activities,such as phospholipase (Schenone and Suarez,1978)which could help understand the mechanism of action and the demons tration of a cytopathic effect of partially purified venom on human cells in culture(Suarez et a1 .,1976)led us to investigate the influence of the venom on two membrane-related processes : the complement-induced hemolysis and influenza virus-promoted hemagglutination . Unfractionated venom gland extracts as well as well as active fractions prepared as described by Suarez et a1 . ,1971, inhibited the hemolysis mediated obtained from various animal
by the complment system
sources, including Rattus norvegicus, a species resistant to
the venom .The extent of inhibition is dose-dependent and can be complete for guinea pig complement .The inhibitory effect,which is heat-sensitive,can be reversed by increasing the concentration of complement . Venom extracts also inhibited influenza virus-induced hemagglutination .The inhibition by the venom was dose-dependent and can be total . It was not possible to detect in the venom extract any neuraminidase activity which could destroy the virus receptor on the membrane . In order to obtain a direct evidence of the interaction of the venom with the cell membrane, antibodies against components of venom extracts were prepared in the rabbit .The antibodies were conjugated with fluorescein isothiocyanate (FITC) .Sheep RBC were incubated with partially purified venom,washed three times with saline and then incubated with FITClabelled antibody .Upon examination on the fluorescence microscope the RBC treated as described showed halos of fluorescence which were absent in control samples . Finally, sheep RBC incubated with crude venom and washed three times with saline produced lesiones in the skin of the rabbit which were undistinguishable from those produced by the direct inoculation of partially purified extracts . The results described provide strong evidence that venom components of L . l aeta bind to the RBC membrane at specific sites which are required for the operation of the complement system as well
as for the attachment of influenza virus .
SCHENONE,H . and SUAREZ,G .(1978) Handbook of Experimental SUAREZ,G .,CONTRERAS,G . and SCHENONE,H .
Pharmacology _48, 247 .
(1976) Toxicon _14, 335 .
SUAREZ,G ., SCHENONE,H . and SOCIAS,T . (1971) Toxicon 9,291 .
~80