C. Tkaczyk et al., In vitro and in vivo immunostimulatory potential of bone marrow-derived mast cells on B- and T-lymphocyte activation, J ALLERG CL, 105(1), 2000, pp. 134-142
Background: Mast cells, which play a unique role in inflammatory and allerg
ic responses, have also been shown to actively participate to the build-up
of protective host defense mechanisms. Recently, they have been shown to st
imulate resting B cells and to form heterotypic aggregates with activated T
cells, resulting in mast cell degranulation.
Objectives: Our aim is to investigate the cytokine requirements and the mec
hanisms by which murine mast cells activate resting B and T lymphocytes,
Methods: Mouse bone marrow-derived mast cells (BMMCs) or peritoneal mast ce
lls were cocultured with resting splenocytes, Activation of B and T lymphoc
ytes was assessed by measuring cell proliferation, blast formation, and cyt
okine release.
Results: We report that addition of IL-4-treated BMMCs to normal spleen cel
ls resulted within 48 hours in a B- and T-cell activation with substantial
amounts of the T-H1 cytokines IFN-gamma and IL-12 and no detectable IL-4, W
e also demonstrate that mature mast cells in the peritoneal cavity are able
to induce spleen cell activation and cytokine release. Addition of antileu
kocyte function-associated antigen 1 and anti-intercellular adhesion molecu
le 1 to the cocultures completely abrogates mast cell-induced blast formati
on and cytokine release. Experiments performed in vivo indicate that spleen
cells from mice injected with BMMCs sustain their capacity of proliferatio
n and cytokine production in vitro without any further stimulation.
Conclusion: These observations suggest that mast cells may exert a helper e
ffect on B and T lymphocytes, initiate T-H1-type immune responses, and may
participate, through this mechanism, in the downregulation of allergic resp
onses.