1 Snake venoms from the genera Micrurus (M. ibiboboca and M. spixii) a
nd Naja (N. naja, N. melanoleuca and N. nigricollis) were analysed, us
ing biological and immunochemical methods, to detect pro-inflammatory
activities, cobra venom factor (COF), proteolytic enzymes, thrombin-li
ke substances, haemorrhagic and oedema-producing substances. 2 The ven
oms of the five snake species activate the complement system (C) in no
rmal human serum (NHS) in a dose-related fashion, at concentrations ra
nging from 5 mu g to 200 mu g ml(-1) serum. Electrophoretic conversion
of C3 was observed with all venoms in NHS containing normal concentra
tions of Ca2+ and Mg2+, but only by venoms from N. naja and N. melanol
euca when Ca2+ was chelated by adding Mg2+-EGTA. 3 Purified human C3 w
as electrophoretically converted, in the absence of other C components
, by the venoms from N. naja, N. nigricollis and M. ibiboboca. However
, only the venoms from N. naja and N. melanoleuca contained a 144 kDa
protein revealed in Western blot with sera against COF or human C3. 4
All venoms, at minimum concentrations of 30 ng ml(-1), were capable of
lysing sheep red blood cells, also in a dose-related fashion, when in
cubated with these cells in presence of egg yolk as a source of lecith
in. Although the venoms from M. spixii and N. nigricollis showed detec
table thrombin-like activity, these and the other venoms were free of
proteolytic activity when fibrin, gelatin and casein, were used as sub
strates. 5 When tested on mice skin, all five venoms were capable of i
nducing an increase in vascular permeability and oedema, but were devo
id of haemorrhagic producing substances (haemorrhagins). 6 These data
provide evidence indicating that Elapidae venoms contain various pro-i
nflammatory factors which may be important in the spreading of neuroto
xins throughout the tissues of the prey or human victim.