Other factors likely to operate include local entrapment of lymphocytes in the lymphoedematous limb, upregulation of apoptosis induced by increased Fas (CD95) levels, as described in IL,12 disordered lymphopoiesis/thymic atrophy,13 and disordered interactions between the lymphoid cells and the lymphatic endothelial cells.10 The interaction between systemic immunodeficiency and lymphoedema is likely to be bidirectional and complex. Here, FAS is linked to thymus atrophy.