Lending a Helping Cell

What am I looking at?

This is a colored scanning electron microscopy image of a human helper T cell, also called a CD4+ lymphocyte.  

Biology in the background

There are several types of T cells in the immune system; the kind pictured here is known as a helper T cell. These cells can recruit or activate many other immune system cells. They help produce antibodies by activating B cells. They recruit and activate macrophages at the site of an infection, helping to destroy the pathogens causing an infection. They also help activate killer T cells to destroy infected or cancerous cells.

One of the main ways helper T cells carry out these varied functions is by using chemicals called cytokines that stimulate a variety of other cells in the immune system.

A helper T cell is about 8 to 10 micrometers in diameter, or roughly eight or nine times smaller than the width of a human hair.

Technique

This image was created using electron microscopy.