Clonal Anergy

Anergy is the concept whereby the human body’s immune system is unable to launch a complete attack and effectively stops itself from being able to properly launch an immune response against an antigen. This may be because the antigen in point may be a host antigen.

Both B-lymphocytes and T-Lymphocytes can become anergic, but they have different ways of becoming anergic and halting the immune response.

When CD8+ T-Cells (Cytotoxic T-Cells) are immature, they drift through the body’s bloodstream. Without having a previous encounter with a pathogen, they are considered to be naďve cytotoxic T cells. In order to be activated, they must go through two stages; recognition and verification.

Recognition (Signal 1) entails the cytotoxic T-cells recognizing that a cell is infected. This occurs due to chemical reactions between the specific proteins and chemicals on the membrane of the infected cell. Once the cell has been recognized to be infected, the cytotoxic T-cell must go through the process of verification.

Verification (Signal 2) involves professional APC’s, or antigen-presenting cells, which are part of the body, but induce a chemical reaction between their cell membrane and the cell membranes of the T-cells. Once cytotoxic T-cells have been activated once, the need for verification is eliminated. Faster responses occur upon reinfection by the same pathogen, because T-cells do not need to undergo verification again.

Helper T-Cells also go through this same process. Verification is vital, because if verification is not undergone, the body assumes that it is attacking itself, and the T-cells undergo a state of anergy, which means that they float listlessly through the body until atrophying.

B-Lymphocytes also have methods of inducing anergy. This is through reaction with soluble antigens in the bloodstream. B-cells are activated by T-cells.

Figure 1.M – Macrophages attacking a cancer cell