Spontaneous Apoptosis of the Lymphocytes in Cord Blood of Late Preterm Newborns

Background/Aims: Apoptosis plays an important role in shaping the repertoire of lymphocytes and in regulating the size of the mature lymphocyte pool. The best-defined regulators of apoptosis in T cells are members of the Fas and Bcl families. Fas/FasL pathway is critically involved in the elimination of mature, self-reactive lymphocytes. Bcl-2 protein is important for lymphocyte survival in response to growth factors and various activating stimuli. We have compared the role of CD4⁺, CD8⁺, Fas, FasL and Bcl-2 in spontaneous apoptosis of T lymphocytes from cord blood and tested there is or not relation to gender.

Patients and Methods: We have introduced 28 late preterm newborns to our studies, 15 females and 13 males. Blood was collected from umbilical artery immediately after cutting cord. We have determined the following parameters: the per cent of CD4⁺ and CD8⁺ lymphocytes, the Fas and FasL phenotype and Bcl-2 using flow cytometer Coulter PC 500, Krefeld, Germany.

Results: We have found the increase per cent of CD4⁺ in females 56.10 %, in relation to males 38.15 %. The same per cent was found for CD8⁺ in both gender: 19.60 % females, 17.35 % males.

The antigen Fas (CD95) was more expressed in females: on CD4⁺ 12.80 %, CD8⁺ 8.15 %, in comparison to males: CD4⁺ 9.89 %, CD8⁺ 6.06 %. FasL (CD95L) was lower per cent in females: both on CD4⁺ 6.92 %, CD8⁺ 5.68 %, in relation to males: CD4⁺ 8.94 %, CD8⁺ 7.04 %. Bcl-2 was a little lower in females on CD4⁺ 96.9 % and evidently lower on CD8⁺ 79.14%. In males we noted on CD4⁺ 97.40% and on CD8⁺ 93.01 %. Summarizing our findings we can underline T lymphocytes in females are more activated, what indicate Fas. Inhibitor of apoptosis Bcl-2 is less expressed in females, in comparison to males lymphocytes.

Conclusion: Our preliminary results seems to indicate spontaneous apoptosis of T lymphocytes is more expressed in female newborns.