TREM-1 is also produced in a soluble form, which lacks the transmembrane domain.[14,15] Soluble triggering receptor expressed on myeloid cells 1 (sTREM-1) proteins are detected in patients suffering from severe infectious diseases including pneumonia, sepsis, and chronic bowel disease.[16,17] Elevated level of sTREM-1 is associated with the disease severity and adverse outcome in patients with sepsis and lower respiratory tract infection.[18,19]. Here, TREM1 is linked to Recurrent lower respiratory tract infections.