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Suppression of lymphocyte transformation by plasma from owl monkeys acutely infected with Plasmodium falciparum
Abstract:
Plasma collected from owl monkeys during the acute phase of Plasmodium falciparum infection was shown to adversely affect several in vitro responses which are considered to be correlates of cell-mediated immune functions of normal monkeys. In the presence of acute-phase plasma, response of normal monkey peripheral blood lymphocytes to stimulation with phytohemagglutinin, concanavalin A, and pokeweed mitogen was severely reduced, as was the ability of peripheral blood lymphocytes to respond to allogenic and xenogenic histocompatible antigens. The transformation response of peripheral blood lymphocytes from normal humans to phytohemagglutinin and concanavalin A was also suppressed. Since acute-phase plasma was not cytotoxic for peripheral blood lymphocytes, decreased responsiveness did not result from cell destruction. Acute-phase plasma appears to block initial steps in lymphocyte transformation.
Insights
Acute-phase plasma from Plasmodium falciparum-infected owl monkeys suppresses normal lymphocyte immune responses. This plasma blocks early lymphocyte transformation without causing cell death, impacting cell-mediated immunity.
Area of Science:
- Immunology
- Infectious Diseases
- Primatology
Background:
- Plasmodium falciparum infection can alter host immune responses.
- Cell-mediated immunity plays a crucial role in controlling parasitic infections.
- Owl monkeys are relevant models for studying malaria due to their susceptibility.
Purpose of the Study:
- To investigate the effect of acute-phase plasma from Plasmodium falciparum-infected owl monkeys on normal lymphocyte functions.
- To determine if this plasma affects in vitro correlates of cell-mediated immunity.
- To elucidate the mechanism by which plasma affects lymphocyte responsiveness.
Main Methods:
- Collected plasma from owl monkeys during the acute phase of P. falciparum infection.
- Assessed the in vitro response of normal monkey and human peripheral blood lymphocytes to mitogens (phytohemagglutinin, concanavalin A, pokeweed mitogen) and allogeneic/xenogeneic antigens in the presence of acute-phase plasma.
- Evaluated lymphocyte cytotoxicity to rule out cell death as a cause of reduced responsiveness.
Main Results:
- Acute-phase plasma significantly reduced lymphocyte responses to mitogens and histocompatible antigens in normal monkeys.
- Human lymphocyte responses to phytohemagglutinin and concanavalin A were also suppressed by the plasma.
- The plasma was not cytotoxic, indicating that reduced responsiveness was not due to cell destruction.
Conclusions:
- Acute-phase plasma from P. falciparum-infected owl monkeys impairs key cell-mediated immune functions.
- The plasma appears to inhibit the initial steps of lymphocyte transformation.
- These findings suggest a potential immunomodulatory role of acute-phase plasma during malaria infection.