MCAT Anatomy > Immune System > Cell Mediated Immunity

Cell Mediated Immunity

Background

Based on T-lymphocytes and although both B-cells and T-cells originate in the bone marrow, T-cells mature in the thymus unlike B-cells which mature in the spleen and lymph nodes. There are three major types of t-cells

Click here to learn more about how immune system cells form in the bone marrow.

Helper (T4) cells

MCAT Immume System - Helper T Cell Activation

Suppressor (T8)

Suppressor (T8) cells help tone down immune response once infection is contained. They may also form memory B cells

Killer T (Cytotoxic)

MCAT Immume System - Killer T Cell

(3) Killer T (cytotoxic) cells have a CD8 surface protein that can directly kill an infected cell by secreting toxic chemicals

These types of cells coordinate an immune response by secreting chemicals known as lymphokines which are capable of recruiting other immune cells such as plasma, cytotoxic, and macrophages and increasing their activity. T-cells bind to antigens presented by major histocompatibility class I molecules (receptors) at the cells surface.

MCAT Immume System - HIV Attack

HIV works by destroying T4 cells and essentially immobilizing the host’s immune systems. These specific cells are the reason why organ transplantation requires the use of immunosuppressants.

Click here to learn more about the structure of HIV here.

Auto-immunity means the attack of the body on itself.

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