Functional characteristics of human peripheral blood alpha/beta TCR+, CD4-and CD8- double-negative (DN) T cells

The function of human peripheral blood alpha/beta TCR positive, CD4- and CD 8- double-negative T lymphocytes (DN cells) in vivo is not completely under stood. The response of; immunomagnetically isolated DN cells to PHA and ant i-CD3 was compared to the response of single-positive (SP) CD4 and CD8 subs ets. Proliferation of DN cells in response to PHA was largely independent o f APC. This suggests activation requirements for DN cells that are differen t from SIP cells, Upon activation, HLA-DR was found to be upregulated early on DN cells, and IL-4 and IL-10 were detected in the supernatants of DN ce lls. These observations in vitro could correspond with an immunoregulatory role of human DN cells in vivo.