Activation of Antigen-Specific CD4+ Th2 Cells and B Cells In Vivo Increases Norepinephrine Release in the Spleen and Bone Marrow

Abstract

The neurotransmitter norepinephrine (NE) binds to the β2-adrenergic receptor (β2AR) expressed on various immune cells to influence cell homing, proliferation, and function. Previous reports showed that NE stimulation of the B cell β2AR is necessary for the maintenance of an optimal primary and secondary Th2 cell-dependent Ab response in vivo. In the present study we investigated the mechanism by which activation of Ag-specific CD4+ Th2 cells and B cells in vivo by a soluble protein Ag increases NE release in the spleen and bone marrow. Our model system used scid mice that were reconstituted with a clone of keyhole limpet hemocyanin-specific Th2 cells and trinitrophenyl-specific B cells. Following immunization, the rate of NE release in the spleen and bone marrow was determined using [3H]NE turnover analysis. Immunization of reconstituted scid mice with a cognate Ag increased the rate of NE release in the spleen and bone marrow 18–25 h, but not 1–8 h, following immunization. In contrast, immunization of mice with a noncognate Ag had no effect on the rate of NE release at any time. The cognate Ag-induced increase in NE release was partially blocked by ganglionic blockade with chlorisondamine, suggesting a role for both pre- and postganglionic signals in regulating NE release. Thus, activation of Ag-specific Th2 cells and B cells in vivo by a soluble protein Ag increases the rate of NE release and turnover in the spleen and bone marrow 18–25 h after immunization.