Human immunodeficiency virus, or HIV for short, is a retrovirus that targets the body’s immune system. Over time, HIV infection can lead to acquired immune deficiency syndrome or AIDS for short, making clients more vulnerable to other infections and certain tumors that a healthy immune system would usually be able to fend off.
All right, let’s quickly review some physiology. The immune system consists of white blood cells that protects us from pathogens, and destroys tumor cells. Now, the immune system has two main branches that work together, and include the innate and the adaptive immune responses.
So, the first is the innate immune response, which involves non-specific cells like neutrophils and macrophages that act as first-responders, as well as dendritic cells, which then activate the adaptive immune response. This response is highly specific, and is mediated by cells called lymphocytes, which include T and B cells. T cells can be further divided into CD4+ and CD8+ T cells. CD4+ T cells are also known as T helper cells, because they interact with dendritic cells, and in turn help activate the rest of the lymphocytes. On the other hand, CD8+ T cells, also known as cytotoxic T cells, are in charge of cell-mediated immunity, where they attack abnormal cells. Finally, B cells mediate a type of adaptive response, called humoral immunity, by secreting antibodies that bind to and destroy specific antigens.