Does interleukin-2 restore lymphocyte responses suppressed by Trypanosoma cruzi ?

There has been disagreement about the ability of exogenous interleukin-2 (IL-2) to restore responsiveness to lymphocytes from either Trypanosoma cruzi-infected animals or normal individuals co-cultured with this parasite. The discrepancy has been attributed to the use of different strains of mice or...

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Bibliographic Details
Published in:Immunology 1993-11, Vol.80 (3), p.445-450
Main Authors: KIERSZENBAUM, F, MEJIA LOPEZ, H, SZTEIN, M. B
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Chagas Disease - immunology
Experimental protozoal diseases and models
Humans
Immune Tolerance - immunology
Infectious diseases
Interleukin-2 - immunology
Lymphocyte Activation - immunology
Lymphocytes - immunology
Medical sciences
Mice
Mice, Inbred Strains
Parasitic diseases
Phytohemagglutinins - immunology
Protozoal diseases
Receptors, Interleukin-2 - analysis
Recombinant Proteins - immunology
Trypanosoma cruzi
Trypanosoma cruzi - immunology
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Summary:There has been disagreement about the ability of exogenous interleukin-2 (IL-2) to restore responsiveness to lymphocytes from either Trypanosoma cruzi-infected animals or normal individuals co-cultured with this parasite. The discrepancy has been attributed to the use of different strains of mice or T. cruzi isolates, or to the use of lymphoid cells from different organs. As T. cruzi inhibits the expression of IL-2 receptors by activated lymphocytes in vitro, we were able to test whether restoration of responsiveness by exogenous IL-2 might depend on the level of suppression present in the system. Human or mouse lymphocytes stimulated with phytohaemagglutinin (PHA) exhibited gradual decreases in IL-2 receptor expression, [3H]thymidine incorporation and IL-2 secretion as the concentration of T. cruzi in the culture increased. Exogenous IL-2 afforded a degree of restoration of both IL-2 receptor expression and [3H]thymidine uptake which was substantial at the lower, but very small--if any--at the higher, parasite concentrations tested. Trypanosoma cruzi could not have competed with the lymphocytes for IL-2 because it did not bind significant amounts of this cytokine. These results suggested that the controversy about the corrective effects of IL-2 may be more apparent than real, reflecting variations in the extent of immunosuppression present in different model systems of T. cruzi-associated immunosuppression.
ISSN:0019-2805
1365-2567