Continuing with the acute bronchitis case, this patient would usually be given a short term steroid “burst” of high dose prednisone. Those high daily dose is usually tapered off over the course of a few days to avoid adrenal exhaustion and withdrawal effects. You see, when you introduce prednisone (which the body recognizes as cortisol) to the body, the adrenals stop making their own supply. The theory behind tapering off of steroids like prednisone is that by slowly removing the external steroid source, the body can adapt and begin making its own again with less stress placed on the system. The practice of tapering in short term therapy, even in higher doses is debated by many clinicians. Some doctors and clinicians claim that not only is a taper not necessary in short term therapy (14 days or less) but it is better to stop this therapy earlier, the adrenals and body adjust just fine. Using a taper just introduces more of the artificial source for a longer period of time, which is best to be avoided to minimize side effects and more quickly restore natural body hormone levels.
Intravenously administered glucocorticoids , such as prednisone , are the standard of care in acute GvHD  and chronic GVHD.  The use of these glucocorticoids is designed to suppress the T-cell-mediated immune onslaught on the host tissues; however, in high doses, this immune-suppression raises the risk of infections and cancer relapse. Therefore, it is desirable to taper off the post-transplant high-level steroid doses to lower levels, at which point the appearance of mild GVHD may be welcome, especially in HLA mis-matched patients, as it is typically associated with a graft-versus-tumor effect. [ citation needed ] . Cyclosporine and tacrolimus are inhibitors of calcineurin. Both substances are structurally different but have the same mechanism of action. Cyclosporin binds to the cytosolic protein Peptidyl-prolyl cis-trans isomerase A (known as cyclophilin), while tacrolimus binds to the cytosolic protein Peptidyl-prolyl cis-trans isomerase FKBP12. These complexes inhibit calcineurin, block dephosphorylation of the transcription factor NFAT of activated T-cells and its translocation into the nucleus.  Standard prophylaxis involves the use of cyclosporine for six months with methotrexate. Cyclosporin levels should be maintained above 200 ng/ml.  Other substances that have been studied for GvHD prophylaxis include, for example: sirolimus, pentostatin and alemtuzamab.