We found that ALPS-FAS patients with CD4 lymphopenia have autoantibodies against CD4-T-cells causing NK-mediated antibody-dependent-cellular-cytotoxicity (ADCC) and that the presence of such autoantibodies is associated with an expansion of the CCR7lowPD-1high circulating T-follicular-helper cells (cTfh) subset that have been most recently associated with autoantibody production (11). Here, CD4 is linked to lymphopenia.