Abstract 4525: Dynamic changes in patterns of ganglioside expression characterize maturation of cytotoxic T cells and natural killer cells into effector cells and suggest a close relationship between the two cell types

Gangliosides are glycosphingolipids that play important regulatory roles in cell signaling. Their patterns of expression during human lymphoid cell development and differentiation, however are not not known. Here, we used the ganglioside-binding B subunits of E. coli enterotoxins (LT-IIa-B, LT-IIb-B and LT-IIc-B) as molecular probes to dissect the membrane ganglioside composition of human CD8+ T cells and NK cells, two important players in the anti-tumor response. Human normal PBMC isolated from leukoreduction filters by Ficoll density gradient centrifugation were stained with recombinant LT-IIa-B, LT-IIb-B or LT-IIc-B, and with monoclonal antibodies to CD3, CD8, CD16, CD19, CD27, CD62L, CD45RA, CD45RO and CD56. Using FACS analysis, we found that ganglioside ligands for LT-IIb-B (avidity: GD1a>GT1b>GM2/GM3) and LT-IIc-B (avidity: GM1>GM2 >GM3/GD1a) were increasingly expressed during transitions from naïve T cells, either (CD8+CD45RA+CD62L+) or (CD8+CD45RO-CD27+), to memory T cells of both central memory (CD8+CD45RA-CD62L+) and effector memory (CD8+CD45RA-CD62L-) phenotypes and from memory T cells (CD8+CD45RO+CD27+) to terminally differentiated effector memory (CD8+CD45RO+CD27-) T cells, with expression of ganglioside ligands for LT-IIb-B exhibiting the most significant increase. Patterns of ganglioside expression in the NK cell subsets were remarkably similar to those observed in the CD8+ T cell subsets: Ganglioside ligands for LT-IIb-B and LT-IIc-B were increasingly expressed during transitions from circulating naïve (CD16dimCD56bright) to effector (CD16+CD56dim) NK cells and from effector NK cells to activated mature (CD16+CD56-) NK cells, with expression of ganglioside ligands for LT-IIb-B exhibiting the most significant increase. No major changes in expression of ganglioside ligands for LT-IIa-B (avidity: GD1b>GM1>GT1b) were detected across either CD8+ T cell or NK cell populations. Taken together these results demonstrate dynamic changes in the patterns of ganglioside expression throughout CD8+ T cell and NK cell differentiation. The unique and shared pattern suggests the existence of cell signaling similarities during development and function of these distinct cell types, and this relationship could prove invaluable in the development of novel cancer immunotherapies. Citation Format: Madison K. Ritter, Mary-Peyton A. Knapp, Taylor A. Johnson, Natalie D. King-Lyons, Lorrie Mandell, Jennifer T. Grier, Terry D. Connell, Sergio Arce. Dynamic changes in p