A blood test can identify components that are essential for a healthy immune system.
Immunology is a science that deals with the immune system and the cell-mediated and humoral aspects of immunity and immune responses.
Immune function tests can determine whether an individual is allergic, and if so, to what. Many diseases result from the immune system defence systems inappropriately targeting normal organs systems resulting in "auto-immune diseases". For this reason, many other immunological tests constitute diagnostic markers for disorders such as lupus, rheumatoid arthritis, diabetes and thyroid conditions. Other immunological tests monitor tissue injury due to inflammation.