| It occurs when a child lacks lymphocytes, the specialized white blood cells that the body uses to fight infection. |
| The wound is then filled by a blood clot containing platelet aggregates, red blood cells, and white blood cells trapped in a fibrin meshwork. |
| There are three chapters devoted to the structure and function of erythrocytes and white blood cells. |
| For example, white blood cells in your urine usually mean that you have an infection. |
| Aggregate formation appears to play a role in the immune response by drawing white blood cells to the site of inflammation. |
| The infection causes the immune system to activate white blood cells and chemicals to fight the bacteria. |
