MAIT cells were primarily identified as Vα7.2 TCR+CD161+ T cells and we examined CD8 and CD4 subsets (Fig. 3a) and found that patients with LCH had an increased proportion of blood CD4+Vα7.2 TCR+CD161+ T cells, and a similar trend was observed in lesions, although this was not significant (Fig. 3b). Here, CD8A is linked to Langerhans cell histiocytosis.