HP and helminthiasis: To test whether Chi3l1 regulates TH2 responses to helminth infection, we measured mesenteric LN (msLN) CD4 T cell responses in wild-type (WT) BALB/c and Chi3l1-/- BALB/c mice that were orally infected with Hp. Consistent with previous studies (51), uninfected Chi3l1-/- mice did not exhibit changes in the numbers of total msLN cells or CD19 B cells (Figures S1A–C).