Analysis of Mononuclear Cell Subsets in Pregnancies with Intrauterine Growth Retardation. Evidence of chronic B lymphocyte activation

We have examined the mononuclear cell (MC) subpopulations of 5 pregnant women: Three of them had a previous history of IUGR, whereas two were primiparae and presented IUGR at the term of gestation. IUGR was confirmed after delivery in three women. The analysis of MC subsets was performed by rosetting and immunofluorescence techniques; both heterologous antisera specific for human immunoglobulins and monoclonal antibodies specific for T cell antigens and for M1 and Ia-like antigens were used. The three patients with IUGR confirmed at birth presented numbers of circulating lymphoid cells positive for cytoplasmic IgM, IgG and IgA and with morphologic features of plasmablasts or plasma cells at least tenfold higher than in normal pregnant women at the term of gestation. Our data suggest that chronic activation of the lymphoid system occurs in pregnant women with IUGR. Maternal abnormal reactivity to fetal antigens or to undiagnosed chronic infections may be likely explanations for this phenomenon. Further studies are clearly needed to clarify the relationship between B-lymphocyte activation and pregnancy and to examine the hypothesis of an altered balance of the immunoregulatory T lymphocyte subsets in patients with IUGR.