CD122-targetted IL-2 signals cause acute and selective apoptosis of B cells in Peyer's Patches.

Interleukin-2 (IL-2) has both pro- and anti-inflammatory properties that have been harnessed clinically and that are used experimentally to modulate leukocyte subsets in vivo. In mice, the bioavailability and half-life of IL-2 in vivo can be increased by complexing recombinant IL-2 with different clones of anti-IL-2 monoclonal antibodies that differentially target the cytokine to cells expressing different kinds of IL-2 receptors. While the impacts of systemic IL-2: anti-IL-2 antibody complex (IL-2C) administration are well-defined in the spleen and peripheral lymph nodes, how immune cells in the gut and gut-associated lymphoid tissues respond to IL-2C is not well characterized. Here, we analyze how major leukocyte populations in these tissues respond to IL-2C. We find that IL-2C targeting cells expressing IL-2 receptor beta cause an acute decrease in cellularity of Peyer's Patches while cell numbers in the lamina propria and intraepithelial lymphocytes are unaffected. Cell contraction in Peyer's Patches is associated with the apoptosis of multiple B cell subsets. Our results are important to consider for understanding off-target impacts of IL-2C regimes in experimental models and for considering how IL-2 may contribute to the etiology or severity of gut-associated conditions such as Crohn's Disease.