Lymphocyte subclasses in pregnancy induced hypertension

To B or not to B cells-mediate a healthy start to life

Maternal immune responses during pregnancy are critical in programming the future health of a newborn. The maternal immune system is required to accommodate fetal immune tolerance as well as to provide a protective defence against infections for the immunocompromised mother and her baby during gestation and lactation. Natural immunity and antibody production by maternal B cells play a significant role in providing such immunoprotection. However, aberrations in the B cell compartment as a consequence of maternal autoimmunity can pose serious risks to both the mother and her baby. Despite their potential implication in shaping pregnancy outcomes, the role of B cells in human pregnancy has been poorly studied. This review focuses on the role of B cells and the implications of B cell depletion therapy in pregnancy. It highlights the evidence of an association between aberrant B cell compartment and obstetric conditions. It also alludes to the potential mechanisms that amplify these B cell aberrances and thereby contribute to exacerbation of some maternal autoimmune conditions and poor neonatal outcomes. Clinical and experimental evidence suggests strongly that maternal autoantibodies contribute directly to the pathologies of obstetric and neonatal conditions that have significant implications for the lifelong health of a newborn. The evidence for clinical benefit and safety of B cell depletion therapies in pregnancy is reviewed, and an argument is mounted for further clinical evaluation of B cell-targeted therapies in high-risk pregnancy, with an emphasis on improving neonatal outcomes and prevention of neonatal conditions such as congenital heart block and fetal/neonatal alloimmune thrombocytopenia.

T lymphocyte subpopulations and lymphocyte proliferative activity in normal and pre-eclamptic pregnancy

The purpose of this study was to assess whether any changes occur in the cellular immunity in normal and pre-eclamptic pregnancy. T lymphocyte subpopulations and the lymphocyte proliferative responses to mitogens (PHA, Con A, PWM) in the fetal calf serum were examined in normal pregnant and pre-eclamptic primiparas in the third trimester of pregnancy. In normal pregnancy the absolute and percentage numbers of CD3+ and CD4+ T cells were significantly lower and the CD4+/CD8+ ratio almost halved, in comparison with non-pregnant subjects. In the pre-eclamptic women a decreased absolute and percentage content of CD8+ T cells and increased percentage of CD3+ and CD4+ lymphocytes were found--in comparison with the normal pregnant women--which led to an almost 2.5-fold increase of the CD4+/CD8+ ratio. No disorders were found in the lymphocyte proliferative responses to mitogens in either normal or pre-eclamptic pregnancy. We conclude that despite the shifts among T lymphocyte subsets, mitogen-induced lymphocyte proliferation presents its functional stability and unchanged reactivity in normal and pre-eclamptic pregnancy.

Decreased levels of circulating CD4+ T lymphocytes during normal human pregnancy

Peripheral blood mononuclear cell (PBMC) populations during human pregnancy have been investigated by many authors, although the different results obtained, principally in relation to T cells, are very discrepant. In this study we aimed to exclude all the possible causes of these discrepancies: small sample size; diurnal rhythm of CD4+ T cells; smoking habits; haemodilution which occurs during pregnancy and inappropriate statistical analysis; in order to determine whether gestation has a definite effect on PBMC populations. We found that the percentage of CD4+ T lymphocytes decreases in the first and second trimesters, returns to the non-pregnant level in the third trimester and remains there in the postpartum period. The percentages of CD3+ T lymphocytes run parallel to those of CD4+ while CD8+ T lymphocytes do not vary. The proportion of CD16+ cells, which include mature NK cells, diminishes in the second trimester and this reduction is maintained in the third trimester and the puerperium. No variation was found in the other PBMC studied (CD20+ lymphocytes, CD14+ monocytes and D/DR+ cells). When parity was considered no difference was seen between primiparous and multiparous women in any of the cell populations tested.