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[Are suppressor T-cells the primary target cells of lead immunotoxicity?]
Abstract:
Studies were performed to investigate the effect of chronic low level lead exposure on the regulatory functions of T cells in the humoral immune response to sheep red blood cells (SRBC) in mice. Female mice were exposed to lead (as lead acetate) in the diet at 545 (group 1) and 2180 ppm (group 2) for 10 weeks. Lead exposure resulting in blood lead levels (PbB) of about 50 micrograms/100 g (group 1) produced a substantial increase of the number of IgG antibodies secreting spleen cells on days 3 and 4 after challenge. At the higher exposure level (group 2; PbB 60-80 micrograms/100 g) a suppression of the number of IgG plaque forming cells was observed. The IgM response was much smaller than the IgG response. Although differences between the group means were small, the results indicate that there also is an enhancement of the IgM response in the lower dosage group on days 3 and 4. In a second experiment the effect of in vivo lead exposure on antigenic competition was examined. Lead substantially reduced the effect of antigenic competition. Results of both experiments suggest that suppressor T cells rather than helper T cells may represent the primary target for lead. Throughout this study serum complement C3 levels were determined. Complement C3 levels tended to be reduced in the lead exposed groups before as well as after inocculation with SRBC.
Insights
Chronic low-level lead exposure impacts T cell regulation of immune responses. Lead exposure can enhance or suppress antibody production and affect immune competition, suggesting suppressor T cells are a primary target.
Area of Science:
- Immunology
- Toxicology
- Cellular Biology
Context:
- Investigating the immunomodulatory effects of environmental toxicants.
- Understanding the impact of chronic low-level lead exposure on adaptive immunity.
- Examining T cell-mediated regulation within humoral immune responses.
Purpose:
- To determine how chronic low-level lead exposure affects T cell regulatory functions in mice.
- To assess the impact of lead on the humoral immune response to sheep red blood cells (SRBC).
- To investigate lead's effect on antigenic competition and identify the primary T cell subset targeted.
Summary:
- Mice exposed to lead acetate (545 or 2180 ppm) showed altered IgG antibody production against SRBC, with lower doses enhancing and higher doses suppressing antibody-secreting cells.
- Lead exposure reduced the effect of antigenic competition and tended to lower serum complement C3 levels.
- Results suggest that suppressor T cells, not helper T cells, are the primary target of lead's immunomodulatory effects.
Impact:
- Highlights the differential effects of lead exposure levels on specific antibody responses (IgG, IgM).
- Provides evidence for lead's disruption of immune regulation and competition mechanisms.
- Identifies suppressor T cells as a key target, informing future research on lead's neurotoxic and immunotoxic mechanisms.