Comparative Parasitology 67(2) 2000 - Peru State College

234 COMPARATIVE PARASITOLOGY, 67(2), JULY 2(X)0
lymphocytes and suppression of NO production.
In the present study, the immunosuppressive
drug had no effect on iNOS induction in T. spira/zs-infected
mice muscles. On the other hand,
during the muscular phase of trichinellosis,
methylprednisolone exerts a suppressive influence
on the subpopulation of CDS lymphocytes
(Boczori et al., unpublished data) with the degree
of change dependent on the doses of larvae
used to infect the host.
Similar investigations on T. pseudospiralis
were not performed because human cases of T.
pseudospiralis have not been reported. Nevertheless,
in severe cases of human trichinellosis
caused by T. spiralis, glucocorticoid chemotherapy
is popular, although still disputable.
It is well known that larvae of T. pseudospiralis
are less immunogenic than those of T. spiralis
(Flockhart, 1986). Irrespective of the fact
that they share 60% of antigens with T. spiralis
larvae, they still possess 8 different proteins. In
the intestinal phase, the adult form of T. pseudospiralis
causes a much weaker inflammatory
reaction than that of T. spiralis (Flockhart,
1986). In the late muscular phase (70 days p.i-X
the presence of T. pseudospiralis larvae resulted
in a level of iNOS stimulation similar to that
caused by T. spiralis larvae (approximately
240%).
Taking into account that the intensity of the
T. pseudospiralis infection was 2 times lower
than that of T. spiralis, we can assume that despite
the lower immunogenicity of the former, it
induced much stronger RNI generation. For example,
on day 7 p.i. the iNOS activity recalculated
per 1,000 muscle larvae of T. pseudospiralis/g
of tissue was about 0.08 nmoles/mg of
protein/min, and during the muscular phase
measured on day 42 p.i. was 0.16 nmoles/mg of
protein/min. In T. spiralis infection, the respective
values for iNOS activity were 0.007 and
0.006 nmoles/mg of protein/min, being about 10
and 26 times lower, respectively, than in T. pseudospiralis
infection.
Thus, the continuous migration of T. pseudospiralis
larvae causes a much greater degree
of damage, but instead of an immunological response,
a set of biochemical defense reactions,
including RNI generation, take place.
The agents present in excretory-secretory
products of larvae induced iNOS for almost 3
months. Still, in order to establish the possible
duration of this effect, it would be necessary to
Copyright © 2011, The Helminthological Society of Washington
carry out a long-term study for at least 6 to 8
mo p.i.
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