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Interactions of TRIC agents with macrophages: effects on lysosomal enzymes of the cell
Abstract:
TWO CHANGES WERE OBSERVED IN THE ACID PHOSPHATASE OF MACROPHAGES THAT HAD INGESTED INFECTIVE TRIC ORGANISMS: the proportion of extralysosomal enzyme rose, while the total amount in the cells fell. Both effects were directly related to the number of organisms ingested and increased with time. When macrophages were inoculated with more than 50 organisms per cell, changes were obvious within a few hours; with 2-10 organisms per cell changes were detectable only after 18 hr. or more. Enzyme appeared in the culture medium as the amount in the cells decreased. Ingestion of organisms killed by heat or treated with antibody did not induce such changes. In infected BHK-21 cells, no changes in acid phosphatase were detected at any stage of the developmental cycle of the organism.
Insights
Ingesting infective Trypanosoma cruzi organisms alters macrophage acid phosphatase levels, increasing extralysosomal enzyme and decreasing total cellular enzyme. These changes correlate with parasite load and incubation time.
Area of Science:
- Cell Biology
- Immunology
- Parasitology
Background:
- Macrophages play a crucial role in the immune response against intracellular pathogens.
- Acid phosphatase is a key lysosomal enzyme involved in cellular degradation.
- Trypanosoma cruzi is an intracellular parasite that infects various host cells, including macrophages.
Purpose of the Study:
- To investigate the changes in macrophage acid phosphatase activity following ingestion of infective Trypanosoma cruzi organisms.
- To determine the relationship between the number of ingested parasites and the observed enzymatic alterations.
- To explore the kinetics of these changes over time and their localization.
Main Methods:
- Macrophages were incubated with varying concentrations of infective Trypanosoma cruzi.
- Acid phosphatase levels and localization (intralysosomal vs. extralysosomal) were assessed over time.
- Control experiments included heat-killed or antibody-treated parasites and infected BHK-21 cells.
Main Results:
- Ingestion of live Trypanosoma cruzi led to an increase in extralysosomal acid phosphatase and a decrease in total cellular enzyme.
- These alterations were dose-dependent on the number of ingested parasites and time-dependent.
- Enzyme was released into the culture medium as intracellular levels decreased.
- No significant changes were observed with non-infective organisms or in infected BHK-21 cells.
Conclusions:
- Infective Trypanosoma cruzi organisms induce specific modifications in macrophage acid phosphatase activity.
- These changes suggest a potential mechanism of parasite-induced host cell modulation or immune evasion.
- The observed enzyme release into the medium may indicate cellular damage or altered secretory function.