Bi-directional relationship of in vitro mast cell-nerve communication observed by confocal laser scanning microscopy

Communication between nerves and mast cells is a prototypic demonstration o f neuro-immune interaction. Recently; we used an in vitro co-culture approa ch comprising cultured murine superior cervical ganglia (SCG) and rat basop hilic leukemia (RBL) cells to study this interaction. Previously, we concen trated mainly on the activation signal from neurites to mast cells (RBL). H owever, it is proposed that mast cell-nerve communication is not a one-side d relationship but a bi-directional one. In the present work, we studied th e communication from mast cells to neurites, We observed that binding of an ti-IgE receptor antibodies to mast cells increases calcium ion concentratio n [Ca2+](i) in SCG neurites, This indicates that mast cell-nerve communicat ion is bi-directional, Confocal fluorescence microscopic images indicated t hat [Ca2+](i) in neurites increased after an increase of [Ca2+](i) in mast cells, The lag-time of neurite activation was several times longer than tha t of mast cell activation. The correlation coefficient between the lag-time s for mast cell and nerve activation was calculated to be 0,81, In addition , the fluorescence images showed that calcium signals in SCG neurites were able to extend to a long distance (100-200 mum) from the site where mast ce lls (RBL) attached to neurites.