The blood protein hCAP‐18 in neutropenia: An 18‐month experience of a new ELISA for clinical use

Abstract

Neutropenia as an isolated clinical finding may include aetiologies ranging from severe disease to a transient condition, and differential diagnosis may be challenging. Previous data and clinical experience suggest that low levels of the neutrophil‐derived protein human 18 kDa cathelicidin antimicrobial protein (hCAP‐18) in the blood are predictive of more severe forms of neutropenia. The objective of this study was to present the results from a newly developed ELISA method that has been used in clinical routine in Sweden since 2018 for quantification of hCAP‐18 in blood plasma. Using this method, we report that patients with severe disease analysed during the study period presented with low or undetectable levels of blood plasma hCAP‐18, validating its use as screening tool for severe neutropenia. Furthermore, neutropenic patients as a group displayed lower levels of hCAP‐18 as compared to blood donors. Within the group of neutropenic patients, those with neutrophil antibodies displayed significantly higher hCAP‐18 levels compared to patients with idiopathic neutropenia. By including an analysis of hCAP‐18 in the primary investigation of neutropenia, an increased accuracy in differential diagnosis is achieved, thus contributing to reduced costs of neutropenia management.

Perturbed NK-cell homeostasis associated with disease severity in chronic neutropenia

“…The log2transformed arbitrary unit Normalized Protein eXpression (NPX) was used for all calculations and visualization. Plasma levels of the human hCAP-18/pro-LL-37 were analyzed using a recently described in-house ELISA 24 .…”

The human cathelicidin hCAP‐18 in serum of children with haemato‐oncological diseases

“…For quantification of hCAP-18 in blood serum, a recently developed enzyme-linked immunosorbent assay (ELISA) validated for clinical use was utilized. For assay details, see Mörtberg et al 20 In short, the hCAP-18 ELISA is a sandwich ELISA with a monoclonal mouse-anti-hCAP-18 as capture antibody (clone H7, Thermo Fisher Scientific, Stockholm, Sweden) and a polyclonal rabbit anti-hCAP-18 detection antibody (OSC0000W, Thermo Fisher Scientific). Recombinant hCAP-18 protein (cAMP, 34-173 aa, Nordic Biosite, Täby, Sweden) was used to construct a calibration curve.…”

“…hCAP-18 in blood serum and plasma has been shown to be stable over long time, stored at −80°C, as evident from previous work. [14][15][16]20 In order to investigate a possible impact of long-term storage on hCAP-18 stability in serum, we performed Spearman correlation tests between hCAP-18 and sample age. There was no correlation for children with acute leukaemia (p = 0.4), nor for children with nonhaematological malignancies (p = 0.7), indicating that hCAP-18 levels in this study were stable following longterm storage.…”

“…17 Vitamin D has the capacity to induce hCAP-18/LL-37 in leukocytes and epithelial cells, 18,19 but it is not known whether vitamin D status affects blood hCAP-18 levels. Reference values for hCAP-18 in adults have been published, 20 but are lacking for children.…”

Citrullination Alters the Antibacterial and Anti-Inflammatory Functions of the Host Defense Peptide Canine Cathelicidin K9CATH In Vitro

“…Like human cathelicidin LL-37, K9CATH is expressed in leukocytes, epithelial cells, and keratinocytes. The concentration of the human cathelicidin hCAP18 (the proform for LL-37) was recently measured in plasma from healthy human controls to range between 2231276 ng/ml (6). In addition, higher levels have been detected in plasma of multiple trauma patients (7) and in skin lesions of patients with rosacea and psoriasis (8).…”