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Protection from O,O,S-trimethyl phosphorothioate-induced immune suppression
K E Rodgers1, D L Haviland, C F Ware
1Division of Biomedical Sciences, University of California, Riverside 92521-0121.
Immunopharmacology
|May 1, 1989
Summary
O,O,S-trimethyl phosphorothioate (OOS-TMP), a malathion impurity, suppressed immune cell generation. Its antagonist, O,O,O-trimethyl phosphorothionate (OOO-TMP), and OOS-TMP pretreatment offered varied protection against this immune suppression.
Area of Science:
- Immunotoxicology
- Environmental Health
- Cellular Immunology
Background:
- Technical malathion contains impurities like O,O,S-trimethyl phosphorothioate (OOS-TMP).
- OOS-TMP has been shown to suppress key immune responses, including cytotoxic T lymphocyte (CTL) and antibody-secreting cell (Ab) generation.
- Understanding the immunomodulatory effects of OOS-TMP and potential protective strategies is crucial for risk assessment.
Purpose of the Study:
- To investigate the protective effects of an OOS-TMP antagonist (OOO-TMP) and OOS-TMP pretreatment against OOS-TMP-induced immune suppression.
- To evaluate the impact of different treatment regimens on immune cell proliferation and function.
- To determine if protection against lung toxicity correlates with protection against immune suppression.
Main Methods:
- Animals were subjected to various treatment regimens involving acute or repeated administration of OOS-TMP and/or OOO-TMP.
- Lymphoid organ sizes were assessed.
- Splenocyte proliferation responses to mitogens (Concanavalin A and Lipopolysaccharide) were measured.
- In vitro generation of antibody-secreting cells (Ab) to sheep red blood cells (SRBC) and cytotoxic T lymphocytes (CTL) to alloantigen were assessed.
Main Results:
- No significant changes in lymphoid organ sizes were observed across treatment groups.
- Splenocyte proliferation responses to mitogens were significantly elevated in groups treated with OOO-TMP alone, co-administered OOO-TMP/OOS-TMP, and repeated OOS-TMP followed by a challenge dose.
- Antibody response to SRBC was significantly elevated following OOO-TMP administration and at a lower dose of repeated OOS-TMP administration.
- No significant alterations in CTL generation were observed across treatment groups.
Conclusions:
- The protective effects against OOS-TMP-induced immune suppression varied depending on the immune parameter assessed.
- Treatments that protected against lung toxicity did not universally protect against all forms of OOS-TMP-induced immune suppression.
- The sensitivity of different immune responses to OOS-TMP suppression influences the observed protective outcomes.