The present invention relates to an isolated human or human-adapted antibody antagonist or fragment thereof that specifically binds Domain I (SEQ ID NO: 9) of human interleukin-1 receptor like 1 (ST2L), comprising a heavy chain complementarity determining region (HCDR) 1 (HCDR1), a HCDR 2 (HCDR2), a HCDR 3 (HCDR3), a light chain complementarity determining region (LCDR) 1 (LCDR1), a LCDR 2 (LCDR2), and a LCDR 3 (LCDR3), wherein a) the HCDR1 comprises SEQ IDNO: 96; b) the HCDR2 comprises SEQ ID NO: 110; c) the HCDR3 comprises SEQ ID NO: 84; d) the LCDR1 comprises SEQ ID NO: 130; e) the LCDR2 comprises SEQ ID NO: 90; and f) the LCDR3 comprises SEQ ID NO; 131.