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IgA-driven antibacterial activity against Streptococcus pneumoniae by mouse lung lymphocytes
P Sestini1, L Nencioni, L Villa
1Institute of Respiratory Diseases, University of Siena, Italy.
The American Review of Respiratory Disease
|January 1, 1988
Summary
Mouse lung lymphocytes (LL) possess natural antibacterial (NA) activity against Streptococcus pneumoniae. This activity is mediated by a specific subset of IgA-bearing helper T cells, highlighting a novel immune defense mechanism.
Area of Science:
- Immunology
- Cell Biology
Background:
- Lung lymphocytes (LL) play a role in local defense mechanisms.
- Natural antibacterial (NA) and natural killer (NK) activities of lung cells were investigated.
Purpose of the Study:
- To investigate the role of lung lymphocytes (LL) in local defense mechanisms.
- To characterize the natural antibacterial (NA) activity of mouse LL against S. pneumoniae type 3.
- To compare the effector cells responsible for NA and NK activities.
Main Methods:
- In vitro assay using S. pneumoniae type 3 and YAC-1 tumor cells.
- Purification of LL using carbonyl iron and magnet treatment.
- Depletion experiments with antibodies and complement to identify effector cells.
- Functional assays with purified IgA and antibodies.
Main Results:
- Purified LL exhibited enhanced NA and NK activities.
- NA activity was mediated by Thy 1.2+, L3T4+, aGM1+ lymphocytes, distinct from NK effector cells (Thy 1.2-, aGM1+).
- NA activity was inhibited by anti-IgA but not anti-IgG, suggesting IgA mediation.
- Purified IgA specific for S. pneumoniae enhanced LL antibacterial activity.
- Specific IgA antibodies induced NA activity in alveolar macrophages and peritoneal exudate cells.
Conclusions:
- Mouse LL include a subset of IgA-bearing helper T cells with NA activity against S. pneumoniae.
- This NA activity is driven by an IgA-dependent mechanism.
- IgA antibodies can induce antibacterial activity in other immune cells like macrophages.