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Abrogation of graft-versus-host reaction by dieldrin in mice
P Hugo1, J Bernier, K Krzystyniak
1Institut Armand-Frappier, Laval-des-Rapides, Québec, Canada.
Abstract:
Sublethal exposure to the organochlorine pesticide, dieldrin, decreased the T-cell immune response in mice. Indeed, a transient inhibition of the mixed lymphocyte reactivity (MLR) was noted at 7 days after intraperitoneal exposure to 0.6 LD50 dieldrin. The present study was undertaken to further investigate the effects of dieldrin on the T-cell immune response, using the graft-versus-host reaction (GVHR) as a model, in order to assess T-cell subset efficiency. Lymphoid cells of A/J mice injected intraperitoneally 7 days earlier with 36 mg/kg body weight dieldrin were transferred into H-2-incompatible F1 hybrids. With this model, known to induce a marked GVHR, we have observed that dieldrin inhibited the potential of parental cells to induce a GVHR in hybrid mice. This effect could not be attributed to a direct cell cytotoxicity, nor to the modulation of major T-cell subsets as shown by thymic and peripheral T-cell subpopulation analysis. Collaboration processes between these cellular subsets seem to represent a potential site for the dieldrin-induced suppression.
Insights
Sublethal exposure to the organochlorine pesticide dieldrin impairs T-cell immune responses. Dieldrin suppressed the graft-versus-host reaction (GVHR) in mice, indicating a potential disruption in T-cell collaboration.
Area of Science:
- Immunology
- Environmental Toxicology
- Cellular Biology
Background:
- Organochlorine pesticides, like dieldrin, are environmental contaminants with known toxic effects.
- Previous studies indicated dieldrin can suppress T-cell mediated immune responses, such as mixed lymphocyte reactivity (MLR).
- The specific mechanisms underlying dieldrin's impact on T-cell subsets and their interactions remain unclear.
Purpose of the Study:
- To investigate the effects of sublethal dieldrin exposure on T-cell immune responses.
- To utilize the graft-versus-host reaction (GVHR) model to assess T-cell subset efficiency following dieldrin exposure.
- To elucidate the potential mechanisms of dieldrin-induced T-cell suppression.
Main Methods:
- Mice (A/J) were exposed intraperitoneally to dieldrin (36 mg/kg body weight).
- Lymphoid cells from exposed mice were transferred into H-2-incompatible F1 hybrid recipients to induce GVHR.
- T-cell subpopulations in thymus and periphery were analyzed to assess cellular modulation.
Main Results:
- Dieldrin exposure significantly inhibited the capacity of parental lymphoid cells to induce a GVHR in hybrid mice.
- The observed suppression was not due to direct cytotoxicity of dieldrin on cells.
- Analysis revealed no significant modulation of major T-cell subpopulations.
Conclusions:
- Sublethal dieldrin exposure suppresses T-cell mediated immunity, specifically impacting the GVHR.
- Dieldrin's inhibitory effect on T-cell responses may stem from interference with intercellular collaboration rather than direct cell killing or T-cell subset depletion.
- Further research is needed to pinpoint the exact molecular pathways involved in dieldrin-induced T-cell suppression.