CD19 and mantle cell lymphoma: Through a single-cell analysis of pre-infusion CD19-CAR T cell products derived from 22 patients with DLBCL, FL, or MCL, they identified a heterogenous profile of engineered T cells, characterized by polyfunctional CD41+ and CD81+ subsets secreting IFN-γ, IL-8, IL-5, granzyme B, and/or MIP-1a [33].