Biology Reference
In-Depth Information
5.11 B Cell
The primary role of the B cell is produce antigen-specific antibodies that will
increase cell-mediated clearance of the antigen. The role played by NE in regulating
the magnitude of an antibody response has been indicated primarily by studies con-
ducted in NE-depleted mice. Most data showed that NE depletion decreased the Th
cell-dependent antibody response (reviewed in Ref.
[126]
), suggesting that NE might
exert an enhancing effect on the endogenous activity of immune cells that generate
the antibody response. A plethora of
in vitro
studies followed and showed that NE did
indeed affect B cell activity directly. For example,
2
AR stimulation and elevation
of cAMP affected B cell proliferation by either inhibiting
[127-129]
or enhancing
[130-132]
B cell proliferation. The reader is referred to the following comprehensive
review of all of the early history in this area of defining the effects of NE on B cell
activity
[126,133]
. It is now clear that many of these findings were important in lay-
ing the groundwork for the studies described in this section, which have started to
identify the molecular mechanism responsible for mediating the enhancing effect of
NE on the antibody response (
Figures 5.3 and 5.4
).
Pharmacologic characterization of the NE effect on the antibody response showed
that NE produced an enhanced response
[134]
, a result supported by the finding that
selective
2
AR stimulation enhances the antibody response with a magnitude and
kinetics similar to that produced by NE, and this enhancement was blocked with the
2
AR antagonist propranolol
[135]
. These results suggested that NE stimulates the
β
2
AR
Naive CD4+
T Cell
Differentiation
β
2
AR
Th1 Cell
Th2 Cell
Figure 5.3
2
AR expression by murine CD4
T cell subsets.
The murine naïve CD4
T cell expresses the
2
AR, and this expression is maintained as the naïve T cell differentiates
to a Th1 cell. However, as the naïve T cell differentiates to a Th2 cell,
2
AR expression is lost;
the mechanism by which this occurs remains unknown.
