Artwork entitled Inside the AIDS Virus", showing a possible mechanism by which the Human Immunodeficiency Virus (HIV) disables the immune system through the interaction of a monocyte (blue) & a T4 cell (pink). In a normal immune response, monocytes function to engulf & process foreign antigens, presenting fragments (as MHC molecules) for recognition by receptors (CD4) on T4 cells. However, HIV also binds to CD4 & may prevent this antigen presentation. Here, an antigen presented by the monocyte appears yellow. The cup-shaped CD4 is filled with HIV protein (green) & so is "blind" to the MHC and the antigen. Thus the immune response is cancelled. First published New Scientist, 10 February 1990."