MedTerms Medical Dictionary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Find a medical definition by using the A-Z listing (select a letter)

T cell: A type of white blood cell that is of key importance to the immune system and is at the core of adaptive immunity, the system that tailors the body's immune response to specific pathogens. The T cells are like soldiers who search out and destroy the targeted invaders.

Immature T cells (termed T-stem cells) migrate to the thymus gland in the neck, where they mature and differentiate into various types of mature T cells and become active in the immune system in response to a hormone called thymosin and other factors. T-cells that are potentially activated against the body's own tissues are normally killed or changed ("down-regulated") during this maturational process.

There are several different types of mature T cells. Not all of their functions are known. T cells can produce substances called cytokines such as the interleukins which further stimulate the immune response. T-cell activation is measured as a way to assess the health of patients with HIV/AIDS and less frequently in other disorders.

T cell are also known as T lymphocytes. The "T" stands for "thymus" -- the organ in which these cells mature. As opposed to B cells which mature in the bone marrow.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Find a medical definition by using the A-Z listing (select a letter)

Copyright © 1996-2003 MedicineNet, Inc. All rights reserved.
MedicineNet, Inc. does not endorse any of the services or products offered on this page.

Information in the MedTerms Medical Dictionary is provided for informational purposes only and is not a substitute for professional medical advice. You should not use this information for diagnosing or treating a medical or health condition. You should carefully read all product packaging. If you have or suspect you have a medical problem, promptly contact your professional healthcare provider.