Some data exists to suggest T cell-mediated cytotoxicity as an alternative mechanism for platelet destruction in immune-mediated thrombocytopenia (ITP) [25], and both CD4 and CD8 T cells infiltrate the pulmonary interstitium of patients with CVID [51, 52], but no causal link has yet been shown between CD8 T cell differentiation and ILD or AIC manifestation. Here, CD4 is linked to interstitial lung disease.