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Immunological parameters,selected for evaluation of immunological vigor.
Immunity is composed of various cells as mentioned above and their numbers
and functions are assessed as immunological parameters. We selected immunological
parameters which are apt to decline with age, at the time of diseases and
at the exposure to stress. They are :
Number of T cell,
Number and ratio of T cell subpopulations ;
CD4+T cells, CD8+T cells, CD4/CD8T cell ratio, CD8+CD28+T cell,
naive T cell, memory T cell, naive/memory T cell ratio,
B cells and NK cells
T cell proliferative activity (TA) and various cytokine production that are assessed in vitro culture in the presence of mitogenic substance. TA reflects value obtained
in vitro using determined number of cells and thus converted to the value at the
whole body level (TCPI: T cell proliferative index) by considering the
number of T cells in the peripheral blood.
Assessment and judgment of immunological vigor.
- Immunological score and grade.
The values of immune parameters were standardized by assigning scores of 3 (high level), 2 (moderate level) and 1 (low level) according to the data base obtained from 500 healthy people. After standardization, the scores of 7 or 8 types of immune parameters were summed and the numerical value obtained for each individual was termed the score of immunological vigor (SIV). These scores were then classified into 5 grades, from V to I. We call this step as scoring of immunological vigor (SIV). The SIV can be expressed as a numeral and judged as high or low.
- Immunological age and T lymphocyte age.
- Estimation of immunological age by TCPI.
T cell proliferation index (TCPI) showed a negative correlation with chronological age and it is possible to guess the age of an individual from the TCPI. The age thus obtained is named immunological age (IA) which is not necessarily the same with the chronological age. The immunological score is well correlated with the immunological age.
When immunological score is high, IA is often younger than chronological age, and when immunological score is low, IA is often older than chronological age.
- Estimation of T lymphocyte age by number of CD8+CD28+ T cells
The number of CD8+CD28+ T cells decreases clearly with advance of age as. Thus it is possible to estimated the age of individual by the number of CD8+CD28+ T cells. The age estimated in this way is defined as “T lymphocyte age”（TA).
TA is based on the number of CD8+CD28+ T cells which can be easily obtained by flow cytometric analysis of lymphocytes.
When immunological score is high, TA is often younger than chronological age, and when immunological score is low, TA is often older than chronological age.
IA is based on the proliferative activity of T cells and therefore lymphocytes must be cultured in vitro, while TA is based on the number of CD8+CD28+ T cells which can be easily obtained by flow cytometric analysis of lymphocytes.
Magnitude of IA is well correlated with that of TA and both are convenient indicators to see the level of immunological vigor at a glance.
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