Bone marrow origin of mucosal mast cells

Area of Science:

• Immunology
• Cell Biology
• Parasitology

Background:

• Infection with Nippostrongylus brasiliensis induces mucosal mast cell (MMC) accumulation in the small intestine.
• Athymic mice lack MMC, while W/Wv mice are deficient in both MMC and connective tissue mast cells (CTMC).
• CTMC are known to originate from bone marrow.

Purpose of the Study:

• To elucidate the developmental origin of mucosal mast cells (MMC).
• To determine the role of the thymus and bone marrow in MMC and CTMC development.

Main Methods:

• Hematopoietic and lymphoid tissues from normal mice were transplanted into athymic and W/Wv mice.
• The MMC response to N. brasiliensis infection was evaluated in recipient mice.
• Different cell populations (bone marrow, thymus, spleen) and treatments (anti-Thy 1) were tested for their ability to restore mast cell populations.

Main Results:

• MMC deficiency in athymic mice was corrected by thymus or spleen cell grafts, but not bone marrow.
• Both MMC and CTMC deficiencies in W/Wv mice were corrected by bone marrow or spleen cell grafts.
• These findings indicate that MMC, like CTMC, derive from bone marrow precursors but require thymic influence for maturation.

Conclusions:

• Mucosal mast cells (MMC) derive from bone marrow, not the thymus.
• MMC development is dependent on a thymus-derived factor.
• Athymic mice have bone marrow mast cell precursors but lack thymic influence, while W/Wv mice lack mast cell precursors but possess thymic influence.