CD4 and lymphopenia: In humans studies, CD4 depletion mAb also only induced a transient deletion and T‐cell numbers also rapidly repopulated within a month10 followed by a persistent lymphopenia for many months.10, 25, 28 Furthermore, as found in mice also,4 this treatment targeted the naive CD4 T‐cell subsets and there was particularly rapid repopulation of the CD40RO memory T‐cell subset,28, 29 which would contain the pathogenic T cells.