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Updated: Jun 14, 2026
Analyzing the Functions of Mast Cells In Vivo Using 'Mast Cell Knock-in' Mice
Published on: May 27, 2015
Mast cells protect against airway Mycoplasma pneumoniae under allergic conditions
N M Michels1, H W Chu, S C LaFasto
1National Jewish Health, 1400 Jackson Street, Denver, CO 80206, USA.
Background:
Infection with Mycoplasma pneumoniae (Mp) in asthma can occur both acutely and chronically with an associated Th2 inflammatory response and/or increased numbers of bronchial mast cells. Mast cells have previously been shown to promote mycoplasma clearance in mice; however, it is unknown whether mast cells would aid Mp clearance under allergic conditions.
Objective:
Our aim was to determine the impact of allergic inflammation on mast cell-mediated lung Mp clearance. Furthermore, as we have previously demonstrated an essential role for IL-6 in lung Mp clearance we also investigated the role of mast cell-derived IL-6.
Methods:
Mast cell-deficient (WBB6F1/J-Kit(W)/Kit(W-v)) mice were challenged with ovalbumin to induce airway inflammation before Mp infection. The role of mast cell-derived IL-6 in bacterial clearance was further investigated by reconstitution of mast cell-deficient mice with IL-6(-/-) mast cells.
Results:
Allergic mast cell-deficient mice exhibited increased lung Mp burden compared with control littermates. Intravenous adoptive transfer of wild-type and IL-6(-/-) mast cells significantly improved Mp clearance in mast cell-deficient mice. Acutely after Mp infection, allergen-challenged mast cell-deficient mice had increased levels of the pro-inflammatory cytokines IL-6 and TNF-alpha in the bronchoalveolar lavage (BAL) fluid. The total number of neutrophils was also increased in mast cell-deficient mice.
Conclusions:
Our results establish that mast cells aid host defense against Mp in an allergic setting and that while IL-6 is necessary for lung Mp clearance, mast cell-derived IL-6 is not required.
Insights
Mast cells help clear Mycoplasma pneumoniae (Mp) infections in allergic asthma by aiding host defense. However, mast cell-derived IL-6 is not essential for this lung Mp clearance.
Area of Science:
- Immunology
- Respiratory Medicine
- Microbiology
Background:
- Asthma is linked to Mycoplasma pneumoniae (Mp) infection, Th2 inflammation, and increased mast cells.
- Mast cells promote mycoplasma clearance in mice, but their role in allergic conditions is unclear.
Purpose of the Study:
- To investigate how allergic inflammation affects mast cell-mediated lung Mp clearance.
- To determine the role of mast cell-derived IL-6 in lung Mp clearance.
Main Methods:
- Mast cell-deficient mice were sensitized to ovalbumin to induce allergic airway inflammation before Mp infection.
- Reconstitution of mast cell-deficient mice with wild-type or IL-6(-/-) mast cells was performed to assess IL-6's role.
Main Results:
- Allergic mast cell-deficient mice showed higher lung Mp burden.
- Adoptive transfer of mast cells improved Mp clearance.
- Allergen-challenged mast cell-deficient mice had elevated IL-6, TNF-alpha, and neutrophils in BAL fluid.
Conclusions:
- Mast cells contribute to host defense against Mp during allergic inflammation.
- IL-6 is crucial for lung Mp clearance, but mast cell-derived IL-6 is not required.
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