CXCL13 and pneumonitis: An increased frequency of ICOS+CD4+ T cells was a better predictor for pneumonitis development than those of CXCL13 or IL-6 levels (Figure 7D and Supplemental Table 3), and combined assessment of both changes in ICOS+CD4+ T cells and CXCL13 levels had an even greater predictive value for later development of pneumonitis (Figure 7D and Supplemental Table 5).