Gene expression profiling demonstrates a molecular link between (angioimmunoblastic T-cell lymphoma) AITL and follicular helper T (TFH) cells (adapted from de Leval et al⁶).

In this molecular profiling study of 18 AITL and 16 peripheral T-cell lymphomas, not otherwise specified (PTCL, NOS) samples, gene set enrichment analyses (GSEA) were performed by using sets of genes representative of distinct normal T-cell subsets, in order to compare the molecular signature of the tumor samples. Panels A and B show enrichment score (ES) curves generated by such analyses. In panel A, genes discriminant between AITL and PTCL, NOS were ranked (according to the signal to noise ratio) from left to right, and GSEA was performed by using a set of 100 genes overexpressed in normal TFH cells; the ES curve is significant, meaning that the AITL samples display significant enrichment in the TFH signature, as compared to PTCL, NOS. In panel B, two AITL samples consisting of purified tumor cell suspensions were compared with 16 AITL tissue samples, and GSEA showed a significant enrichment of the tumor cell suspensions in the set of the 42 core genes (accounting for the enrichment in panel A). Finally the finding that the imprint of the TFH signature was stronger in purified AITL tumor cells samples compared with AITL tissues, validates that the molecular link with TFH cells was related to the neoplastic cells. Panel C show the associated heatmap of these 42 core genes. Expression data from normal T-cell subsets, 2 AITL tumor cell suspension samples (arrows), 16 AITL tissue samples and 16 PTCL, NOS samples are represented. Standardized expression ranges from −2.0 (blue) to 2.0 (red).