ICOS and myasthenia gravis: When thymocytes were stained for PD-1 and ICOS expression, an increase of PD-1 was detected on the thymocytes and the CD4+CD8− SP cells of AChR-MG patients (seven ISP and 11 ISN patients) compared to Con (p = 0.039 and p = 0.028, respectively) (Figure 7).