Immunology Basics - Immunological Computation: Theory and Applications - page 20

u n

M Φ

−

NK natural killer

PMN

−

polymorphonuclear leukocytes

Φ −

M macrophages

−

IFN interferon

Lysis

Figure 1.14 Overall immunity (coverage) with different defense mechanisms.
(From Whitton, J. L., Curr. Top. Microbiol. Immunol. , 232, 1-14, 1998.)

h e importance of self-regulatory mechanisms is evident in clonal expansion (in
humoral immunity) due to the presence of an antigen; this is also observed when
specifi c immune cells are reduced after the clearance of antigens. Such a control of
antibody production is thought of as an idiotypic regulatory network (Jerne, 1974).
Moreover, B cell clonal expansion and proliferation are closely regulated to pre-
vent uncontrolled immune response. h is second signal helps to ensure tolerance
and discrimination between dangerous and harmless invaders. So the purpose of this
accompanying signal in identifying nonself is to minimize false alarms and to gene-
rate a decisive response in case of a real danger. Figure 1.14 depicts defense strategies
(outer layers), involvement of immune cells and molecules (inner circle), and their
interconnecting mechanisms in the biological defense system (Whitton, 1998).

1.6 Signaling and Message-Passing Mechanism
In the immune system, signal diff usion and dialogue are noticeable as two kinds of
communication schemes. h ey play a major role in sharing and passing information
during the immune response. In immune diff usion , the message is passed from one
immunocomponent to others without any feedback. Another scheme is called immune
dialogue , where the immune system components continuously exchange molecular
signals with their counterparts. Immune sensitivity is determined by context, where
an immune cell and a pathogen play on one another. h e body is under constant