Canadian Health&Care; Mall

The amount of inhibition of NK cell activity observed in vivo was about 40 percent, which was about equal to that observed by direct addition in vitro at the concentration of 1X 10_4M aminophylline (2 X 10'M theophylline). The NK cell activity was returned to the level of before administration on the seventh day after cessation of administration (Fig 2A). The NK cell activity could be enhanced by addition of IL-2 even after administration of theophylline when comparing Figure 2A and 2B, but still the inhibition was significant when comparing before and after administration in the presence of IL-2 (Fig 2B). Frequencies of NK Cells Not Changed after Administration of Theophylline in Vivo The total counts of lymphocytes in peripheral blood were not significantly changed comparing before and after administration (data not shown). The percentages of Leu 7 and Leu 11a positive cells (those are considered as surface markers of NK cells) were not significantly changed either (data not shown). The percentages of OKT-3, OKT-4, OKT-8, and OKMI positive cells and the OKT-4/8 ratio were not changed (data not shown). These results suggested that the inhibition of NK cell activity was caused by functional inhibition of individual NK cells, but was not due to a decreased frequency of NK cells in vivo.