[Levels of lymphocyte subpopulations in peripheral fetal blood in Rh(D) erythrocyte isoimmunization in pregnancy].

INTRODUCTION

In the foetus in utero predominates a considerable percentage of immunologically so-called naive lymphocytes of the T and B series. The objective of the presented work was to assess by means of flow cytometry and labelled monoclonal antibodies quantitative changes in cell sub-populations of the foetal immune system before the foetus is altered by severe heamolysis as a result of Rh(D) isoimmunization.

METHOD

The authors obtained by intrauterine puncture of the umbilical cord peripheral blood from 10 foetuses with isoimmunization during the 23rd-35th week of gestation, confirmed by the direct Coombs test and with a mean haematocrit value of 30.8% +/- 8.02. These findings were compared with values in the peripheral blood stream in a control group of 35 foetuses during the 18th-39th week of pregnancy with normal intrauterine development (haematocrit 34.2% +/- 5.87). The authors assessed the haemogram and CD signs in the lymphocyte population.

RESULTS

In the peripheral bloodstream of foetuses with erythrocyte isoimmunization the authors did not detect, as compared with the control group (p > 0.01), a lower haemoglobin level (10.6 +/- 2.77 g/dl vs. 11.9 +/- 2.03 g/dl) a lower haematocrit (30.8% +/- 8.02 vs. 34.2% +/- 5.87) and fewer leucocytes 5.1 +/- 2.39 x 10(9)/l versus 6.97 +/- 3.29 x 10(9)/l. In foetuses with Rh(D) isoimmunization the authors found a higher percentage of T(CD3+) lymphocytes (79.0% +/- 11.23 vs. 73.7% +/- 12.79, but did not prove an increase of activated T lymphocytes (%DR+ from CD3+) (1.0% +/- 0.52 vs. 1.3 +/- 0.58). The percentage ratio of T helper cells (CD+) was higher than in the control group (61.0% +/- 10.25 vs. 56.1% +/- 12.45). In foetuses with Rh(D) isoimmunization there was no difference in the ratio of CD8 positive cells (24.1% +/- 8.23 vs. 23.6% +/- 7.26). Suppressor T cells (CD8+CD11b+) were fewer (4.1% +/- 1.24 vs. 7.5 +/- 11.23) than in the control group. The number of NK cells in foetuses with Rh(D) isoimmunization was 5.1% +/- 3.26 vs. 6.9% +/- 3.86, in isoimmunized foetuses there is a higher ratio of so-called naive T helper cells Th1 (CD4+ CD45 RA+) 49.3% +/- 12.71 vs. 43.0% +/- 12.88. When assessing naive B1 cells (CD19+CD5+), the authors did not find a difference between the two groups (10.4% +/- 6.20 vs. 9.06% +/- 12.1). The ratio of CD4: CD8 in the group with isoimmunization was higher than in the control group (3.1 +/- 1.39 vs. 2.5 +/- 1.13).

CONCLUSION

In isoimmunized foetuses in the initial stages of haemolysis no detactable immune response with significant changes in the lymphocyte sub-populations was found.