Serum adenosine deaminase and its isoenzyme activities in pregnancy

ADA is widely distributed in human tissues, which may contribute to the maturation of the immunological system, especially the proliferation and differentiation of lymphoid cells, and seems to be critical at different stages of the maturation process. The activity of ADA changes in diseases characterized by the alteration of cell-mediated immunity. In this study we examined changes in serum total ADA activity and the patterns of two ADA isoenzymes, ADA-1 and ADA-2, in healthy pregnant women, and evaluated the possible role of the alteration of cell-mediated immunity during pregnancy as causes of changes in ADA activity.

We measured serum activities of total ADA, ADA-1 and ADA-2 in healthy pregnant women (n=129) and age-matched healthy nonpregnant women (n=42). We divided the study group into three different subgroups: first trimester, second trimester and third trimester.

Serum ADA, ADA-1 and ADA-2 activities in healthy pregnant women were significantly lower than in nonpregnant women (p<0.001, p<0.001 and p<0.01 respectively). ADA (p<0.001) and ADA-2 (p<0.001) activities in the first trimester were significantly lower than in the control group. However, there were no significant differences between the first trimester and control group according to their ADA-1 activities (p=0.016). ADA (p<0.001), ADA-1 (p<0.001) and ADA-2 (p<0.008) activities in the second trimester were significantly lower than in the control group. Combined trisomy 21 risk, biochemical trisomy 21 risk, age risk and trisomy 18 + Nuchal translucency (NT) risk were calculated using a first trimester screening test in 63 pregnant women. Furthermore, trisomy 21 risk, age risk and trisomy 18 risk were calculated by triple test in 52 pregnant women. ADA, ADA-1 and ADA-2 activities were not significantly correlated with risks in the first trimester screening test. ADA-1 activity was slightly significantly negative correlated with age risk (r= -0.314, p<0.05) and trisomy 18 risk (p<0.05) in the triple test. ADA (p<0.05) and ADA-2 (p<0.05) activities were slightly significantly correlated with gestational age, while there was no significant correlation between ADA-1 activity and gestational age.

Serum ADA activity may be useful for clinical diagnosis and observation of high-risk pregnancies in which cell-mediated immunity has been altered.