Importantly, we provide evidence that this pathway might be active in human TLS, both in inflammatory conditions and in the earliest phases of malignant transformation (in the MALT lymphoma parotid treated in vitro with ICOS blocking antibody), where ICOS/ICOSL activation is continuously required for LT production and the aberrant lymphoid chemokine/cytokine expression. This evidence concerns the gene ICOS and MALT lymphoma.