White blood cells are an integral component of your blood. They are a vital part of your immune system, detecting and dealing with infections. There are different types of white blood cells. If you have an abnormally low or high number of white blood cells, it might indicate an underlying problem.

What are white blood cells?

White blood cells, also called leucocytes, detect and deal with infections or foreign molecules that enter your body. White blood cells will produce antibodies to fight the infection and help with other immune responses.

They are one of four main components of your blood, along with red blood cells, platelets and plasma.

What are the types of white blood cells?

There are different types of white blood cells which each have different roles to play.

The main types of white blood cells are:

• Neutrophils and monocytes, which mainly fight against bacteria.
• Eosinophils and basophils are mainly involved in allergic responses.
• Lymphocytes, which can be T-cells or B-cells, produce antibodies against foreign organisms and are especially involved in fighting off viruses.

What are the problems involving white blood cells?

An abnormally low or high number of white blood cells might indicate an underlying problem.

If you have too few of the healthy type of white blood cells called neutrophils, this is known as neutropenia. It might be a sign of a serious problem, or it might just be because you've got a virus. It can also come on after cancer treatment

If you have too many white blood cells, it could be because you’ve got a bacterial infection. Also leukaemia, a type of cancer, makes you produce large numbers of abnormal white blood cells.