It has been shown recently that one gamma/delta cell line, termed IDP2, derived from a immunodeficient patient recognizes the CD1c molecule on the surface of target cells. In light of these data, we have tested 43 cloned and 11 polyclonal gamma/delta cell lines derived from peripheral blood of 19 donors following nonspecific mitogenic stimulation. In this panel, which included lymphocytes expressing various combinations of gamma and delta chains, only one clone, termed J2B7, was found to interact with target cells via a CD1c-dependent recognition pathway. These J2B7 lymphocytes have, like IDP2, a delta chain which results from the frequent V1/J1 rearrangement while they use a distinct V gamma gene segment. The data support the view that the CD1c major histocompatibility complex "class I-like" gene product does not have a pivotal contribution to the repertoire of peripheral blood gamma/delta cells in adult individuals.