CD4 and autoimmune thrombocytopenic purpura: Both of these types of immune-mediated platelet destruction were dependent on the presence of CD4+ T cells, as CD4+ T-cell depletion completely abrogated the ability of the β3 integrin-reactive splenocytes to induce severe thrombocytopenia or bleeding symptoms, suggesting that CD4+ helper T cells may be responsible for the initiation of immunopathology in ITP [133].