08-11-2011, 09:43 PM
Immunosuppression
Glucocorticoids suppress the cell-mediated immunity. They act by inhibiting genes that code for the cytokines IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-8 and IFN-γ, the most important of which is IL-2. Smaller cytokine production reduces the T cell proliferation.[21]
Glucocorticoids do, however, not only reduce T cell proliferation, but also lead to another well known effect called glucocorticoid induced apoptosis. The effect is more prominent in immature T cells that still reside in the thymus, but also affect peripheral T cells. The exact mechanism underlying this glucocorticoid sensitivity still remains to be elucidated.
Glucocorticoids also suppress the humoral immunity, causing B cells to express smaller amounts of IL-2 and of IL-2 receptors. This diminishes both B cell clone expansion and antibody synthesis. The diminished amounts of IL-2 also causes fewer T lymphocyte cells to be activated.
Since glucocorticoid is a steroid, it regulates transcription factors; another factor it down-regulates is the expression of Fc receptors on macrophages, so there is a decreased phagocytosis of opsonised cells.
http://en.wikipedia.org/wiki/Glucocorticoid
Glucocorticoids suppress the cell-mediated immunity. They act by inhibiting genes that code for the cytokines IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-8 and IFN-γ, the most important of which is IL-2. Smaller cytokine production reduces the T cell proliferation.[21]
Glucocorticoids do, however, not only reduce T cell proliferation, but also lead to another well known effect called glucocorticoid induced apoptosis. The effect is more prominent in immature T cells that still reside in the thymus, but also affect peripheral T cells. The exact mechanism underlying this glucocorticoid sensitivity still remains to be elucidated.
Glucocorticoids also suppress the humoral immunity, causing B cells to express smaller amounts of IL-2 and of IL-2 receptors. This diminishes both B cell clone expansion and antibody synthesis. The diminished amounts of IL-2 also causes fewer T lymphocyte cells to be activated.
Since glucocorticoid is a steroid, it regulates transcription factors; another factor it down-regulates is the expression of Fc receptors on macrophages, so there is a decreased phagocytosis of opsonised cells.
http://en.wikipedia.org/wiki/Glucocorticoid