Immune system plays important role in the maintenance of health in all living animals. However, such an important system decays with advance of age, starting at as early as the 3rd decade in humans. Some case shows early starts as early as teen age, and the other case maintains high level of immunological level at 5th or 6th decade. It is important to note that the onset and magnitude of immunological decline are different from individual to individual leading to a great heterogeneity among individuals. Causes of immunological decline with age are multifactorial, partly genetic and partly environmental, including lifestyle, food, physical exercise, sleep, habits (smoking and alcohol) and various stresses. It is good to note that declined activity of the immune system is somehow reversible, although not totally.  For instance, restoration of immunological function was attempted in cancer patients by infusion of activated autologous T cells [1-3]. There are many reports that magnitude of immune system is partly reversible by improvement of lifestyles [2-10,12,13] and by mitigation of stressful environments [3-6]. One of purposes of this paper is promoting and encouraging people to start immunological restoration by using any possible methods available. By immunological restoration people becomes more powerful and active in terms of physical endurance and psychological strength, and can have more enjoyable life. This is partly related with intimate interaction of the immune system with nervous and endocrine systems (the so-called neuroendocrine immune system) [11]. Furthermore, people may be able to overcome or delay the appearance of many kinds of diseases, including cancer [2]. There are many ways to restore immunological vigor, but the first accessible step is improvement of lifestyle, including food, physical exercise, sleep and change of stressful environment. As already mentioned above, magnitude of immunological level is different among individuals, the first step for immunological improvement is the exact determination of immunological level for each individual. The second step is thorough examination of lifestyle including food, physical exercise, habit of tabaco and alcohol, sleep, environmental stress and vaccination.

Figure 1: Immunological Grade of Healthy People and Cancer Patients Immunological Grade of Cancer Patients Shows Lower Immunological Grade as Compared with Healthy People.

In this step one has to carefully examine lifestyle and find out any defect in lifestyle that probably impedes the immune system. For instance, when one finds that physical exercise is not sufficient in daily life, then one can plan to incorporate physical exercise in his lifestyle. When sleep is not suitable in lifestyle, one can start to improve sleep at nighttime. In this way, some of them who intend to improve lifestyle can successfully restore immunological vigor to some degree. If not successful, one can achieve improvement of lifestyle in other routes. Anyway, the first point is the discovery of immunological defect by using assessment of immunological vigor, explained later. It is important to understand which part of the immune system is depressed. Then one can find out later whether the defective portion of the immune system is recovered or not, after the effort of using available method of immunological restoration. In this paper, the first point deal with the method of immunological assessment. The second is explanation of individual variation and gender difference in immunological vigor. The third is influence of diseases on immunological vigor. In the Final section, micro blood sampling method is introduced for assessment of immunological vigor at home, together with questionnaire about lifestyle to find out any defect.

The Quantitative Assessment of Immunological Vigor

The immunological vigor is an imaginative term and the magnitude is calculated by using many immunological parameters obtained from numbers and functions of various subsets of lymphocytes in the peripheral blood. The magnitude of immunological vigor is temporarily expressed as number, and the range is roughly classified as 5 grades, as described later. The first trial was reported in 2007, comparing elderly people without diseases and cancer patients [2]. Using the same method, more precise trial was done in 2009 [3], including immunological restoration. Since immune functions are based on various immunological cells, number of immunological cells can be important indicator for immunological vigor. Then we thought proliferative activity of T cells is the next important factor of immunological vigor. The third is cytokines produced by cells composing the immune system. The assessment of immunological vigor was based on 10 parameters obtained from lymphocytes and then the number of parameters can be reduced to 7 by excluding the assessment of cytokines. Five parameters can be selected to T cell function.

Table 1: In The Beginning 10 Parameters Are Shown Below.

CD3+T cells (number/µl), 2) CD4+ naïve T cells (number/µl), 3) NK cells (number/µl), 4) B cells (number/µl), 5) Ratio of CD4+T cells/CD8+T cells, 6) Ratio of CD4+ naïve T cells / CD4+ memory T cells, 7) T cell proliferative index (TCPI) as described later.  8) IL-2 production level in vitro under stimulation, 9) IL-4 production level in vitro under stimulation, 10) IFN-??production level in vitro under stimulation. Each index was given a score from 1 to 3 (1: low, 2: moderate, 3: high) by comparison to values of population’s data base. The summation of score of 10 parameters was named score of immunological value (SIV) ranging between 10 to 30. This SIV was then classified into 5 grades; Grade V (SIV30-29; sufficiently high), Grade IV (SIV 28-26; fairly good), Grade III (SIV25-22; slight decline), Grade II (SIV21-17; moderate decline), Grade I (SIV16-10; severe decline). Table 1 is summarizing the scoring and the grading of immunological vigor using 10, 7, 5 parameters, respectively. Immunological grade is useful to easily judge the immunological level in individual case. The level of SIV was compared between 60 healthy people and 20 cancer patients. SIV level of healthy people showed gradual decrease with age (y=-0.042x + 28.1, R2=0.07) and were mainly distributed between 22 and 30. SIV level of cancer patients also showed gradual decrease with age (Y=-0.112x+30.4, R2=0.10).  Immunological grade is clearly lower in cancer patients as compared with so-called healthy people without apparent diseases (Fig.1). We defined a new parameter, T-cell proliferation index (TCPI) which was calculated by using the number and proliferation activity of T-cells [2]. The number of T-cells is essential for the maintenance of immune function. In addition, T-cell proliferation is the most essential function of T-cell immunity, including the process of antigen recognition and clonal division of T-cells. There are 4 combinations of T cells in terms of number and proliferative capacity. ?Both number and proliferative capacity are sufficient; ?Number is sufficient, but proliferative capacity is insufficient; ? Number is insufficient and proliferative capacity is sufficient; ? both are insufficient. Therefore, we arrived at the conclusion that we needed a new parameter which reflected both the number and proliferative capacity of T-cells. The new parameter, TCPI was calculated by the following equation. TCPI = T-cell proliferation activity x (T-cell number per μL/1000 and this is reflective of T cell function at whole body level, not in vitro culture level [1]. Therefore, TCPI is one of good parameters for the assessment of immunological grade.

Gender Difference

Gender-related differences in humans are commonly observed in behavior, physical activity, disease, and lifespan. However, the notion that age-related changes in the immune system differ between men and women remains controversial. We focused on gender difference in aging of the immune system using 162 healthy men and 194 healthy women, ranging in age from 20 to 80 years. Flow cytometric analyses were carried out on T cells and their subsets, and NK cells. In addition, the proliferative activities and cytokine-producing capacities of T cells in response to anti-CD3 monoclonal antibody stimulation were assessed [14].

Table 2: The Data Are Summarized.

Age-related decline of RBC is evident in men, but not in women, and gender difference is observed. Lymphocytes shows a trend of age-related decrease in men and women, and the decline is steeper in men (p<0.001). Age-related decline of T cells is evident in men, but not in women and gender difference is observed. Age-related decline of CD8⁺T cells is shown in both men and women with no gender difference. Age-related decline of CD3⁺T cells, CD8⁺CD28⁺T cells, T cells proliferative index, T cell immune score and B cells are shown in both men and women with gender difference. In gender difference, decline of the slope is steeper in men than in women.  CD4+T cells, CD4/CD8 T cells ratio and NK cells show age-related increase with gender difference (m>f). NK cells also shows age-related increase both in men and women with gender difference (m>f). Moreover, a trend of age-related decreases was observed in IFNγ, IL-2, IL-6, and IL-10 production, when lymphocytes were cultured under anti-CD3 monoclonal antibody stimulation. The rate of decline in IL-6 and IL-10 production was greater in men than in women (p < 0.05).

Difference in Immunological Grade among People Healthy People Patients with Non-Cancerous Diseases and Patients with Cancer

We need information of immunological vigor using a large number of healthy people and patients suffering from various diseases. So we decided to select 7 parameters from the immunological data in order to efficiently perform assessment of immunological vigor. Selected 7 parameters are 1) number of CD3+T cells, 2) number of CD8+CD28+T cells, 3) ratio of CD4+T cells to CD8+T cells, 4) number of CD4+naïve T cells, 5) ratio of CD4+naïve to CD4+ memory T cells, 6) NK cell, 7) B cells. All data can be obtained by flow cytometric analysis, and the process is efficient and relatively costless. Number of CD8+CD28+T cells lineally declines with age and it is possible to assess immunological age of people and we named it as T cell related age [1]. Using the simplified assessment of immunological grade, mentioned above, nearly 18,000 cases were analyzed [15]. They are composed healthy people (6684), patients with non-cancerous diseases (5725) and patients with cancer (5487). These people were classified as immunological grades from I to V as shown Figure 2. 

Figure 2: Comparison of Distribution of Immunological Grade in Healthy People (6684 M2571/F 4113), Patients with Non-Cancerous Diseases (5784 M3150/ F2537) and Patients with Cancers (5487 M2667/ F 2820).

Three groups indicate peak at Group III (slight decline), roughly showing normal distribution. The level of grade IV (fairly good) is apparently higher in people without diseases than other groups. While the level of grade II (moderate decline) is lower in people without diseases than other groups. In other words, patients with diseases belong to groups of lower grades as compared with other groups. In addition, it is important to note that approximately 2/3 of so-called healthy people belong to grade III, belonging to relatively low level of immunological vigor. It can be said that people without notable disease look healthy, but many of them belong to immunologically slightly too moderately lower level and need immunological restoration.

Assessment of Immunological Level by Micro Blood Sampling Method from Fingertip

Micro blood sampling method is usually employed for assessment of blood glucose level. This method is useful for those who want to know blood sugar level at home without visiting clinic. The same method is applicable for assessment of immunological vigor. About 30 µl of peripheral blood is enough for the assessment of 7 parameters of immunological vigor. Micro blood sampling method is useful for people either with diseases or without notable diseases who want to get information of immunological level or grade. In addition to the assessment of immunological level, people are requested to write in the questionnaire about lifestyle.

Table 2: Summary of questionnaire and comment.

Comment: Please Try to Improve Sleeping Disorder

Habit composed of 42 questions. Questions are composed of food, physical exercise, habit for smoking and alcohol, sleep and stress. This questionnaire is useful to find out defects in lifestyle habit. It is usually not easy to improve defects of lifestyle. An individual person understands clearly the presence of defects in lifestyle, because many questions are answered by the individual himself or herself.

The article funded by author Hirokwa working under Institute of Health and Life Science, Venture fraud Company Originating from Tokyo Med. Dent. University, Tokyo, Japan.

Note: The fund was raised from personal savings, but not the Institute of Health and Life Science, Venture fraud Company Originating from Tokyo Med. Dent. University, Tokyo, Japan as this institution was never encouraged the quality young researchers. So I would never recommend this institution for the quality young researchers for their studies.

1. Hirokawa K and Utsuyama M. Assessment of Age-related Decline of Immunological Function and Possible Methods for Immunological Restoration in Elderly. Handbook on Immunosenescence Basic Understanding and Clinical Applications (Editors Fulop T, Franceschi Claudio, Hirokawa K and Pawelec G) Springer Nature Switzerland AG. 2019; 2767-2793.
2. Hirokawa K, Utsuyama M, Kikuchi Y and Kitagawa M. Scoring of immunological vigor: Trial assessment of immunological status as a whole for elderly people and cancer patients. Immunosenescence (Ed. Pawelec G) Landes Bioscience. 2007; 15-23.
3. Hirokawa K, Utsuyama M, Ishikawa T, Kikuchi Y, Kitagawa M Fujii Y, Nariuchi H, Uetake H and Sugihara K. Decline of T cell-related immune functions in cancer patients and an attempt to restore them through infusion of activated autologous T cells. Mech Ageing Develop. 2008; 130: 86-91.
4. Fulop T, Larbi A, Hirokawa K, Mocchegiani E, Lesourd B, Castule S, Wikby A, Franceschi C and Pawelec G. Immunosupportive therapies in aging Clinical Interventions in Aging. 2007; 2: 33-54.
5. Hirokawa K and Utsuyama M. The Judgment on the Effect of the Immunized Milk by Immunity Evaluation Method Food and Development. 2008; 44: 78-79.
6. Kuroda R, Higuchi H, Yoshida K, Yonejima Y, Hisa K, Utsuyama M, Osawa K and Hirokawa K. Effects of chocolate containing Leuconostoc mesenteroides strain NTM048 on immune function: a randomized, double-blind, placebo-controlled trial Immunity and Aging. 2018; 15: 29-38.
7. Wheatley-Guy CM, Rosenthal AC, Gastineau DA, Katsanis E, Johnson BD and Simpson RJ. Exercise and the immune system: taking steps to improve responses to cancer immunotherapy. J Immunother Cancer. 2021; 9: 1872.
8. Barrea L, Muscogiuri G, Frias-Toral E, Laudisio D, Pugliese G, Castellucci B, Garcia-Velasquez E, Savastano S and Colao A. Nutrition and immune system: from the Mediterranean diet to dietary supplementary through the microbiota. Crit Rev Food Sci Nutr. 2020; 61: 3066-3090.
9. Larbi A, Lesourd B and Fulop T. The complex relationship between nutrition and immnosenescence. Handbook on Immunosenescence Basic Understanding and Clinical Applications (Editors Fulop T, Franceschi Claudio, Hirokawa K and Pawelec G) Springer Nature Switzerland AG. 2019; 2523-2538.
10. Bigley AB, Baker FL, Spielmann G and Simpson RJ. Aging immunity and the impact of physical exercise. Handbook on Immunosenescence Basic Understanding and Clinical Applications (Editors Fulop T, Franceschi Claudio, Hirokawa K and Pawelec G) Springer Nature Switzerland AG. 2019; 2823-2879.
11. Fulop T, Claudio F, Hirokawa K and Pawelec G. Neuroendocrine-Immune Network and Its 2 Age-Related Changes. Handbook on Immunosenescence Basic Understanding and Clinical Applications Springer Nature Switzerland AG. 2019; 1409-1423.
12. Simpson RJ, Campbell JP, Gleeson M, Krüger K, Nieman DC, Pyne DB, Turner JE and Walsh NP. Can exercise affect immune function to increase susceptibility to infection? Exerc Immunol Rev. 2020; 26: 8-22.
13. Kim JH, Kim DH, Jo S , Cho MJ, Cho YR, Lee YJ and Byun S. Immunomodulatory functional foods and their molecular mechanisms. Experimental & Molecular Medicine. 2022; 54: 1–11.
14. Hirokawa K, Utsuyama M, Hayashi Y, Kitagawa M, Makinodan T and Fulop T. Slower immune system aging in women versus men in the Japanese population. Immunity & Ageing. 2013; 28: 19-28.