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Supplementary Material for: The CD6 Scavenger Receptor Is Differentially Expressed on a CD56dim Natural Killer Cell Subpopulation and Contributes to Natural Killer-Derived Cytokine and Chemokine Secretion

posted on 18.12.2010, 00:00 by Braun M., Müller B., ter Meer D., Raffegerst S., Simm B., Wilde S., Spranger S., Ellwart J., Mosetter B., Umansky L.
The CD6 scavenger receptor is known to be expressed on virtually all T cells and is supposed to be involved in costimulation, synapse formation, thymic selection and leukocyte migration. Here, we demonstrate that CD6 is differentially expressed by a subpopulation of peripheral CD56dim natu- ral killer (NK) cells and absent on CD56bright NK cells. CD56dimCD16+ cells represent the major NK subset in the periphery, and most cells within this group are positive for CD6. Most killer immunoglobulin-like receptor- and immunoglobulin-like transcript-positive cells also belong to the CD6+ subpopulation, as expected from their restricted expression on CD56dim NK cells. In addition, CD6+ NK cells are similar to the newly identified CD94lowCD56dim NK subpopulation and most distant from the recently defined CD27+ NK subpopulation based on the reverse correlation of expression between CD6 and CD27, a marker associated primarily with CD56bright NK cells. With respect to CD6 function on NK cells, direct CD6 triggering did not result in degranulation but induced secretion of cytokines (interferon-γ and tumor necrosis factor-α) and chemokines [CXCL10 (IP-10), CXCL1 (GRO-α)]. Thus, CD6 expression on peripheral NK cells marks a novel CD56dim subpopulation associated with distinct patterns of cytokine and chemokine secretion.