Exploring the in vitro expansion of CD4 T cells. For improved culturing of CD4 T cells linked to FNAIT

Abstract

Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a rare disease that may cause serious bleedings in the fetus or neonate of a woman who has developed antibodies against the fetus’ platelets. Development of FNAIT has been linked to the presence of platelet reactive CD4 T cells that help B cells to develop into antibody producing plasma cells. To be able to conduct research on such T cells, the Immunology research group must be able to expand and keep them in long term cultures. Recent work revealed that several established T cell clones had started proliferating poorly. In an attempt to understand why and to possibly improve the culturing of future T cell clones, this study looked into some of the conditions that may influence the growth of these cells when expanded in vitro. The established anti- CD3 expansion culture protocol was compared to one that used PHA, but no advantage of using the latter was detected. It was demonstrated that different B-LCLs used as growth promoting feeder cells expressed varying levels of the surface molecules B7-1 and B7-2. This did however not seem to influence their feeder capacity despite the fact that expanding CD4 T cells were shown to express high levels of CD28, which costimulates growth when bound by B7. Expanding CD4 T cells also expressed the inhibitory molecule PD-1, and it was revealed that expression of its ligand, PD-L1, was induced in B-LCLs when used as feeder cells along with PBMCs. Whether this influences the efficiency of an expansion culture is yet to be determined.