Cb. Palatnikdesousa et al., EXPERIMENTAL MURINE LEISHMANIA-DONOVANI INFECTION - IMMUNOPROTECTION BY THE FUCOSE-MANNOSE LIGAND (FML), Brazilian journal of medical and biological research, 27(2), 1994, pp. 547-551
The fucose-mannose ligand (FML) of Leishmania donovani is a complex gl
ycoprotein fraction present in pro- and amastigotes, that interferes w
ith parasite-macrophage interactions in vitro. In the present study, w
e have tested the potential immunoprotective effect of FML on L. donov
ani infection in inbred female BALB/c mice. The protection schemes inc
luded three weekly intraperitoneal administrations of FML, supplemente
d or not with saponin. Mice were challenged by intravenous injections
of 2 x 10(7) amastigotes of leishmania donovani (LD-1S/MHOM/SD/00-stra
in 1S) obtained from CB hamsters' infected spleens. After 15 days of i
nfection, we monitored the splenocyte proliferative response to FML in
vitro by ELISA for specific antibody response, and by parasite quanti
fication as ''Leishman-Donovan Units'' in liver. A significant (P<0.00
1) protective effect of FML with saponin, but not of FML or saponin al
one, was shown by the reduction of parasite burden in liver and by the
enhancement of splenocyte proliferation. The antibody response, very
low at 15 days of infection in both untreated and control animals, sho
wed a pronounced increase (P<0.001) in animals sensitized with FML/ sa
ponin. Taken together, our results represent a 79.1 and 89.1% increase
in specific proliferative and antibody responses, respectively, and a
n 84.4% protection in reduction of parasite liver burden. The protecti
ve potential was specifically due to FML (P<0.001). Under the present
conditions, no toxic or nonspecific effect could be attributed to sapo
nin. A detailed study of the molecular events related to vaccination a
gainst murine visceral leishmaniasis with total and fractionated FML i
s currently underway.