The Effect of Immune Sera Upon Uptake and Intracellular Survival of Leishmania Donovani in Mononuclear Phagocytes
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Date
1994-12
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Addis Ababa University
Abstract
The effect of sera from patients with acute visceral leishmaniasis on
phagocytosis of L. donovani by human macrophage-like THP-l cells was examined
using microscopic and radiometric methods. Leishmania antibody-positive sera
from clinically asymptomatic subjects, sera from treated individuals, and sera from
endemic and non-endemic controls were also tested. In the microscopic
phagocytosis assay, enhanced uptake ofpromastigotes was observed at 3,6, and 24
hrs after addition of sera from patients with active disease, individuals with treated
disease, or asymptomatic subjects with positive antibody titres compared to sera
from endemic or nonendemic controls and assays performed without human sera.
In some experiments, phagocytosis in the presence of sera from patients with active
disease was greater than that observed using sera from asymptomatic individuals
with positive, but somewhat lower antibody titres. Enhanced phagocytosis was
positively correlated with L. donovani-specific ELISA antibody titres and the
correlation was higher when data from treated patients was excluded from the
analysis. Measurement of phagocytosis using the radiometric method did not detect
differences between groups. Numbers of viable parasites 48 hrs after phagocytosis
were also greater using serum compared to adding no serum to the cultures.
Parasite viability was also positively correlated with the level of phagocytosis,
suggesting that intracellular killing was not affected by pretreatment of parasites or
phagocytes with different groups of serum.
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Biology