Summary auto-generated
This study investigated the role of macrophages in the murine immune response to Actinobacillus actinomycetemcomitans, a gram-negative bacterium associated with periodontal disease. Female BALB/c mice were treated with carrageenan to suppress macrophage function, then immunized with heat-killed A. actinomycetemcomitans. Carrageenan-treated mice showed partial suppression of delayed-type hypersensitivity (DTH) response, reduced interferon-gamma production, lower serum IgG and IgM antibody levels, and delayed lesion healing compared to untreated controls. Adoptive transfer experiments revealed that antigen-pulsed macrophages from immunized donors only partially restored immune responses in carrageenan-treated recipients, while complete spleen cell transfer fully restored responses. Naive macrophages from sham-immunized donors failed to enhance immunity. These results demonstrate that macrophages play a partial but not exclusive role in inducing immune responses to A. actinomycetemcomitans, suggesting that other antigen-presenting cells, particularly dendritic cells, also contribute to the adaptive immune response against this periodontopathogen.
Key findings
- Carrageenan-induced macrophage suppression in mice resulted in partial reduction of DTH response, antibody production, and interferon-gamma levels to A. actinomycetemcomitans
- Antigen-pulsed macrophages transferred to macrophage-depleted mice only partially restored immune responses and lesion healing, while complete spleen cell transfer fully restored immunity
- Macrophages alone are insufficient for mounting complete immune responses to A. actinomycetemcomitans, indicating other antigen-presenting cells like dendritic cells contribute to adaptive immunity
- Carrageenan treatment delayed wound healing of bacterial lesions despite partial preservation of immune function, linking macrophage activity to tissue repair
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