The pro-protein of the antimicrobial peptide LL-37 is called human cathelicidin hCAP-18 (pro-LL-37). Numerous distinct cell types are capable of producing hCAP-18, although the majority of circulating hCAP-18 is generated by bone marrow neutrophil precursors. Additional indicators were required since neutrophil count, which is employed as a marker for myelopoiesis, did not necessarily correspond to neutrophil production in the bone marrow.

For a study, the reference range for blood hCAP-18 levels in healthy children was established by the researchers. The serum hCAP-18 in several diagnostic groups of children with haemato-oncological illnesses at diagnosis were compared. The research revealed that patients with non-hematological malignancies had serum hCAP-18 levels comparable to those of healthy children, while children with disorders that affect myelopoiesis, such as acute leukemia, aplastic anemia, or myelodysplastic syndrome, had low hCAP-18 levels.

Children with chronic myeloid leukemia had significant amounts of hCAP-18 in their blood, likely due to the abundance of myeloid cells at all phases of differentiation. They proposed that the examination of serum hCAP-18 gave further knowledge about myelopoiesis in children with haemato-oncological disorders, which may have future consequences for evaluating myelopoiesis in therapeutic treatment.