In vitro-cultivated, tumor-infiltrating B cells (TIBs) from non-small cell lung cancer (NSCLC)—which commonly harbors KRAS and EGFR mutations (3)–are able to present antigen to and activate CD4 TIL, while some TIB subsets can have an equally immunosuppressive effect on CD4+ T cells (15). Here, CD4 is linked to non-small cell lung carcinoma.