The immune system consists of various specialized organs, molecules and cells in the body that plays protection role against diseases. Assessment of the immune system in psychoneuroimmunology involves research dedicated to stress-neuro endocrine-immune interactions and their consequences for immunomodulation (Vedhara, & Irwin, 2005). The immune system is prone to a wide range of infectious agents on daily basis. The system is however capable of clearing the pathogens long before they have an opportunity to result in diseases. The immune system is composed of two components namely innate and acquired components. During attack the innate system immediately takes on cells to the infected area, triggers repair and kills the pathogens. If the pathogen escapes the innate immune mechanism, the acquired immune system is triggered. The acquired immune system is highly specific and slowly increases its immunity with time. When the same pathogen attacks the body again, the acquired immunity responds fast and is more intense (Cohen & Herbert, 1996).
Since the immune system is composed of complex network of components, successful fight against pathogens requires a harmonious communication between these organs. The effectiveness of the immune system is measured by two methods namely; in vitro and in vivo methods. The two methods have been widely researched to gain insight into the complex interactions between organs, molecules and cells. There are a number of in vitro methods which include; cytotoxicity assays, lymphocyte proliferation, antibody assays and lymphocyte subsets. The following paragraph will describe the lymphocyte subsets in vitro method (Vedhara, & Irwin, 2005).
The rationale behind lymphocyte subset method is that complete eradication of pathogens depends on the efficiency of immune cells and appropriate cell ratios. This has led to a widespread use of total white blood cell (WBC) counts and lymphocyte subsets counts as indices of immune system efficiency. This method has three advantages. From various investigations it has been suggested that significant changes occurs in WBC subpopulation in response to severe stress. The measurement of cell counts is therefore an effective way of assessing the effects of stress. Secondly, the measurements of cell activation markers offer information on the extent and nature of cellular activation. This may offer insight into ways in which stress mat affects the immune system (Byrne-Davis & Vedhara, 2008).
Thirdly, it is possible to know whether apparent alterations in the immune system are due to changes in the functional efficacy of the cells or simply to changes in the cell numbers. On the other hand, this method consists of two shortcomings. The cell numbers do not correlate well with cell function and thus impossible to know the functional efficacy of cells from cell numbers measurement. In addition the cell numbers vary depending on the number of factors such as migration and circadian rhythms (Vedhara, & Irwin, 2005).
Integrated into vivo measurements are widely used because their outcome results are of greatest clinical relevance compared to in vitro method. The rationale behind this method is that hypersensitivity, an adaptive immune response, results in tissue damage. Delayed hypersensitivity is slow and takes more than 12 hours to develop. Several types of DTh have been studied but only the tuberculin type is widely applied. This method is considered a suitable assay in measuring a preceding exposure to a specific antigen as well as in the determination of specific immunodeficiencies. However, this method fails to determine where the immune system impairment has taken place and the nature of the immune response generated. Further, DTh antigen is likely to be influenced by a previous antigen exposure (Byrne-Davis & Vedhara, 2008).
References
Byrne-Davis, L., & Vedhara, K. (2008). Psychoneuroimmunology. Social and Personality Psychology Compass, 2 (2), 751-764. Cohen, S., & Herbert, B. (1996). Health Psychology: Psychological Factors and Physical Disease from the Perspective of Human Psychoneuroimmunology. Annual Review of Psychology, 47, 113-142. Vedhara, K., & Irwin, R. (2005). Human Psychoneuroimmunology. USA, Oxford University Press.