Studies on the immunomodulatory effects of vitamin D

The effect of vitamin D on T lymphocytes was investigated using the test of active E-rosettes formation. It was found that: 1. A single oral administration of 600,000 IU of vitamin D2 causes a significant increase in the formation of active E-rosettes. The peak of the increase was found 24 hours after the administration of vitamin D. The formation of E-rosettes the seventh day of the study was comparable with the pre-administration value; 2. Sera with higher concentration of 1,25-dihydroxyvitamin D[1,25(OH)2D] cause a significant increase in the formation of active E-rosettes; 3. Vitamin D is capable of reverting significantly the effect of a serum factor which suppresses the active E-rosettes formation. The authors observed a significant decrease in the effect of trypsin on the lymphocytes after oral administration of a single oral dose of 600,000 IU of vitamin D2. The trypsin-treated lymphocytes regained their lost capacity to bind sheep red blood cells (SRBC) when incubated with AB serum at 37 degrees C for 3 hours. The recovery of E-rosettes-forming capacity of trypsinised lymphocytes considerably increased when the cells were incubated with serum containing higher concentration of 1,25(OH)2D of 600,000 IU of vitamin D2.