Relationship between adenosine deaminase activity and cytokine-secreting T cells in normal pregnancy

To evaluate the relationship between plasma adenosine deaminase activity and the proportion of cytokine-secreting T cells as causes of changes in adenosine deaminase activity in normal pregnancy.

Plasma adenosine deaminase activity and the proportions of cytokine-secreting T cells were measured in the peripheral blood of 26 nonpregnant and normal pregnant women in the third trimester. The proportion of CD4-positive T cells secreting interferon-gamma derived from T helper 1 cells, and interleukin-4 derived from T helper 2 cells, were analyzed by flow cytometry. The ratio of interferon-gamma-secreting cells to interleukin-4-secreting cells was taken as the T helper 1/T helper 2 ratio.

Mean plasma adenosine deaminase activity in normal pregnant women, averaged, was significantly lower than that in nonpregnant women (10.3 +/- 0.6 U/L versus 13.8 +/- 0.5 U/L, P <.05). In normal pregnant women, the proportion of interferon-gamma-secreting cells was significantly lower than that in nonpregnant women (20.5% +/- 1.0% versus 24.7% +/- 1.2%, P <.05), but the proportion of interleukin-4-secreting cells did not differ from that of nonpregnant women. Consequently, the T helper 1/T helper 2 ratios were significantly decreased during normal pregnancy. A significant correlation was found between adenosine deaminase activity and the proportion of interferon-gamma-secreting cells (r =.54, P <.05).

Decreased plasma adenosine deaminase activity in normal pregnant women may be in part associated with changes in the immunological status, especially the decrease of the proportion of interferon-gamma-secreting cells.