The immune system recognizes and defends us against internal threats
caused by invading organisms and pathogens. The innate immune system recognizes
bacteria, fungi and other organisms, breaks them down, identifies a characteristic
protein on them (an antigen) and attaches it to the surface of specific cells, which
present it to the adaptive immune system for destruction. The adaptive or acquired
immune system acts once then it is stimulated by the innate system. The adaptive
immune response is initiated by specific interactions between antigen loaded, mature
dendritic cells and naïve CD4+ T cells in the lymph nodes. The five families of immune
cells are: phagocytes, granulocytes, natural killer (NK) cells, lymphocytic T-cells and
lymphocytic B-cells. The four major classes of immune system mediators are
chemotactic agents, cytokines, C-reactive protein and antibodies. A fifth class of
immune network mediators comprises the small molecules, including neurotransmitters,
such as L-DOPA and catecholamines. Risk factors for autoimmune diseases include
exposure to man-made chemicals. Benlysta (belimumab) is approved for treating lupus
erythematosus. AIDS is caused by the retrovirus HIV. Currently, a mixture, or cocktail
of antiretroviral drugs is given in what is often called highly active antiretroviral
therapy, or HAART. Microbes in the intestines and lungs (acquired from the
environment) keep rare invariant natural killer immune cells from triggering
autoimmune diseases.
Keywords: Immune system, innate, adaptive, HIV, HAART, autoimmune
diseases.
