Color enhanced scanning electron micrograph (SEM) of two T-lymphocytes, a type of white blood cell involved in the stimulation (helper T-cells) and regulation (suppresser T-cells) of immune response. Cytotoxic T-cells (killer T-cells) target virus invaded cells and cancer cells, destroying them by lysis. Characteristic of T-lymphocytes are the long microvilli projecting from the cell surface. T-lymphocytes are susceptible to infection by the Human Immunodeficiency Virus (HIV), the causative agent of AIDS. Magnification = x1,300 at 35mm.