(this is one of many FAQ files found at Terry) What is HIV/AIDS? Human immunodeficiency virus (HIV) is a retrovirus that attacks white blood cells known as T4 (CD4) lymphocytes . The function of the T4 cells is to determine if foreign matter such as bacteria or viruses has entered the human body . Upon interaction with a bacterial or viral cell, a T4 cell will alert the immune system to its presence . The immune system responds by attacking and eliminating the foreign matter and any infected cells using an array of white blood cells (both B and T…