Inducing and regulating human naive CD4 T cell proliferation by different antigen presenting cells.

We have shown in previous studies that naive CD4 T cells isolated from human peripheral blood are induced to proliferate by CD4CD11cCD14CD16 dendritic cells presenting the superantigen SEE. Since this population is very poorly expressed in blood, we tried to find other antigen presenting cells (APCs) to induce this proliferation. The aim of the previous studies was to investigate the regulation of T cell proliferation in pediatric monogenic autoimmune diseases and the regulation of this proliferation by regulatory T cells (TREGs). Since the blood samples from pediatric patients were very small, it was important to study other APCs that are more commonly present in the blood. In this study we tested different APCs isolated from controls, CD19 B cells, CD11cCD14 and CD11cCD14 monocytes, CD11cCD14CD16 and CD16 dendritic cells. The different T cell populations, naive effector T cells and regulatory T cells were separated simultaneously from the same sample. We show in these studies that CD19 B cells, CD14 and more specifically CD14CD16, are also able to induce T cell proliferation as previously described with CD14CD16 DCs, but under different conditions. No proliferation was induced with CD14 monocytes. However, these three APCs are less potent than CD16 and inhibition by TREG is more difficult to detect. In addition, when we test the role of CTLA-4 in the regulation of TEFF proliferation, we observe that for some APCs, the inhibition by CTLA-4 was quite different. No inhibition was observed with CD19 B cells in contrast to CD11cCD14CD16 and CD11cCD14CD16.