Delayed-type hypersensitivities (DTH)

Definition

Delayed-type hypersensitivities (DTH) are immune responses that occur 24-72 hours after exposure to an antigen. They are mediated by T cells and result in tissue inflammation and damage.

5 Must Know Facts For Your Next Test

1. DTH reactions involve CD4+ T cells, specifically Th1 cells.
2. Common examples of DTH include contact dermatitis and the tuberculin skin test.
3. Cytokines like IFN-γ play a crucial role in DTH by activating macrophages.
4. The reaction time for DTH is typically between 24 to 72 hours after antigen exposure.
5. Histologically, DTH is characterized by the presence of macrophages and lymphocytes.

Related terms

Immediate Hypersensitivity: A rapid allergic reaction mediated by IgE antibodies that occurs within minutes of antigen exposure.

Th1 Cells: A subset of T-helper cells that produce cytokines like IFN-γ and are involved in cell-mediated immunity.

Cytokines:

Signaling proteins released by cells that have a specific effect on interactions and communications between cells.