Biology Reference
In-Depth Information
evidence supports the involvement of PRL in autoimmune disease
[109, 113-115]
and cancer
[116,117]
.
The INIM system is capable of functioning in the absence of the pituitary gland. As
a matter of fact, INIRs function at the cellular level, and after activation of such cells by
antigens bearing homologous epitopes (homotopes), the CTKs produced maintain the
response at the cellular level, if necessary. However, the HPA axis is invariably activated
by INIM-derived CTKs, and GCs act as an important safeguard against exaggerated
CTK production. During acute illness, GCs and CATs amplify innate immune function.
This is the case under homeostatic conditions as well, where the HPA axis functions in
balance with PRL and GH, so both ADIM and INIM functions exist in harmony
[13]
.
Redundancy is the rule within the IS. There are eight major immunoglobulin
classes. Each may recognize the same epitope on an antigen, yet the defense mech-
anisms activated by each are very different. There is significant redundancy in the
CTK families and in chemokines. There are multiple alternatives in cell-mediated
immunity as well. For instance, a target (cancer) cell may be killed by killer T lym-
phocytes, by NK cells, by NK T cells, by activated macrophages, antibodies, comple-
ment, and so on
[118]
.
It was observed in cancer immunology that a given cancer is attacked by a num-
ber of immune mechanisms in the raw, until all mechanisms are bypassed by the
cancer and it can progress to clinical cancer
[119]
. For this reason, the process of
oncogenesis may take up to 30 years. Several other diseases show similar pathology.
For instance, in asthma the pathological lesions are present at all times, yet symp-
toms are manifested only periodically during “attacks”
[120]
. One may propose that
during the silent periods the pathological process is suppressed/controlled by regula-
tory mechanisms available in the host. Similarly, in Alzheimer's disease numerous
plaques form in the brain, and these patients are severely ill; yet indistinguishable
plaques are found in asymptomatic normal individuals, but in much lower numbers
[121]
. Apparently, the brain is able to compensate for injury to a significant degree,
but not to the extent that occurs in Alzheimer's disease.
1.6 Protection for Life by the Neuroimmune Supersystem
All of us suffer from febrile illness on numerous occasions and recover. This indi-
cates that our INIM system is a very important and efficient defense mechanism.
This wonderful defense system is one that we have for life: it is always there for us,
never lost, and fights for us until the last moment of our existence
[122]
.
The ADIM system does not decline, either. Rather, it undergoes age-related
changes: for example, in older individuals the system is maintained largely by mem-
ory cells, so the thymus has little to do; hence it involutes. However, the thymus may
be reactivated by severe immune depletion, which indicates that the involuted thy-
mus is still a functional organ that is ready to act when necessary
[28,123]
. The loss
of adaptive immunity is not obligatory with aging; it is well preserved in the case of
successful aging. Immunosuppression by Tsr during acute illness is reversible, and it
occurs during healing
[28]
. Moreover, the homeostatic survival of T, B, and NK cells
