Thymus–Marrow Cell Interaction evaluated by PHA Stimulation and Graft versus Host Activity

Abstract

THERE is now abundant evidence for cooperation in certain immune responses between B and T lymphocytes¹ which are respectively of bone marrow and thymus derivation. B cells have been shown to secrete antibody but the helper role of the T cell is less well defined. It has also been suggested that in mice PHA responsiveness can be an exclusive characteristic of T cells². Experiments will be presented in this paper which can be interpreted to indicate that the capacity of dissociated thymus cells to respond to phytohaemagglutinin (PHA) in vitro can be much augmented by the presence of bone marrow cells which could be thought to have a helper role in this respect. A small series of experiments is also presented which suggests that a similar form of cooperation can take place in graft versus host responses.