Two systems discussed by Vedhara and Irwin (2005) that measure the effectiveness of the immune system are the “in vitro” method and “in vivo” measures. The in vitro method measures the loss of specific immunology related cells and how this reduction can leave the individual in a more susceptible state to become infected with a variety of pathogens. One example of in vitro measurements, that became a more common term with the general public in the 1980s with the outbreak of HIV and AIDS, is the white blood cell counts consisting of neutrophils, lymphocytes, monocytes, eosinophils, and basophils (AIDS.Org, 2007). These measurements, in addition to assessing additional immune cell subsets, have some advantages as they can be indicators to overall stress levels in patients. Additionally, they are helpful in determining if there are problems with blood cell production in the bone marrow, noted by lower counts, or if there are significant infections that are being concurrently fought off, noted by an increase in the measured cell count (Vedhara & Irwin, 2005).
There are also limitations in the in vitro measurement system such as the fact that although the levels of cell count can be measured, they often can not be correlated with a disease or disorder. Additionally, it is difficult to take one measurement and consider it to be an accurate reading because cell counts vary based upon factors such as time of day or migration of cells. These variables cause too much noise in terms of measuring the effectiveness of the immune system (Vedhara & Irwin, 2005).
The in vivo measures include observing delayed hypersensitivity tests, which is when the body actually harms itself using its own immune system by having an excessive release of hypersensitive anti-bodies (Vedhara & Irwin, 2005). The advantage of measuring the reactions that occur within the human body is real time experimentation can occur in a real-life situation versus that of experimentation in a laboratory or with animals.
However, there are limitations and risks with this form of measurement such as how inducing this type of reaction in a human being may have significant ethical implications for the person conducting the experiment or measurement. Causing an immune response that results in the destruction of a microbe, which results in an inflammatory response, could cause a great deal of harm to the person (O’Neill, 2005). Additionally, it is very hard to have a control group and a treatment group when you are dealing with all of the variability associated with an individual human being (Vedhara & Irwin, 2005). Hypothetically, one person in the study may be stressed out, another person may have a poor diet, another person could be in top physical fitness, or socioeconomic status, age, race or gender could impact the response.
AIDS.Org (2007). Complete blood count (cbc). Information, Education, and Action. Retrieved September 19, 2007 from the World Wide Web: http://www.aids.org/Factsheets/121-Complete-Blood-Count-CBC.html
O’Neill, L. (2005). Immunity’s early-warning system. Scientific American, 292(1), 38-45.
Vedhara, K., & Irwin, M.R. (2005). Human Psychoneuroimmunology. New York, NY: Oxford University Press.