T lymphocytes from the blood of two thymoma patients with hypogammaglobulinaemia suppressed the in vitro proliferation of allogeneic pre-B cells. Both patients lacked pre-B and B cells in blood and bone marrow. It is possible that pre-B cells, as well as B cells, may be targets for suppression by T cells in thymoma patients with hypogammaglobulinaemia.
