CD28 and gestational diabetes: When PBMCs were stimulated with anti-CD3/anti-CD28, there was a significant increase in CD8+ T lymphocytes and a significant decrease in CD4+ T lymphocytes, in relation to cells cultured with only a medium, both in the GDM group (p = 0.0004 and p < 0.0001, respectively) and in the control group (p < 0.0001 and p < 0.0001, respectively).