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Delayed-type hypersensitivity is mediated by a sequence of two different T cell activities.
Journal of Immunology (Baltimore, Md. : 1950)
|November 1, 1984
Summary
The early phase of delayed-type hypersensitivity (DTH) requires serotonin release, and the late phase depends on this early serotonin response. This suggests a sequential cascade in DTH reactions involving T cells and mast cells.
Area of Science:
- Immunology
- Cellular Biology
Background:
- Delayed-type hypersensitivity (DTH) involves early (2-hr) and late (24-48 hr) skin reactions.
- The early DTH component is T cell and mast cell dependent, involving serotonin release.
Purpose of the Study:
- To investigate the relationship between the early and late components of DTH.
- To determine the role of serotonin in the cascade of DTH reactions.
Main Methods:
- Pharmacological agents were used to block serotonin release or activity before and after skin challenge.
- Kinetic analysis examined the temporal relationship between early and late DTH phases.
- Adoptive cell transfer was used to study T cell populations in DTH.
Main Results:
- Agents blocking serotonin before challenge inhibited both early and late DTH components.
- Serotonin blockade after the early response had no effect on the late phase.
- A fixed 10-12 hour gap was observed between early and late DTH phases, dependent on the early response onset.
Conclusions:
- DTH is a cascade initiated by T cells releasing factors that trigger mast cells to release serotonin.
- Serotonin facilitates endothelial gaps, allowing a second T cell population to enter and induce the late DTH response via lymphokine release.