Polymyxin B-immobilized fiber (PMX) columns have traditionally served as a cornerstone for treating endotoxemic septic shock. However, recent evidence suggests their utility extends to non-infectious conditions like the acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF). Researchers recently conducted an in vitro study to evaluate PMX column neutrophil removal and its impact on various leukocyte subtypes under controlled stimulation.

Selective Adsorption of Activated Leukocytes

Specifically, the study utilized whole blood from healthy donors treated with lipopolysaccharide (LPS) to simulate leukocyte activation. Consequently, the results demonstrated that PMX columns possess a significantly higher removal capacity for monocytes and granulocytes compared to control columns. Furthermore, the column preferentially targeted activated CD11b-positive neutrophils. This selective removal is vital because these activated cells often drive the hyper-inflammatory state seen in critically ill patients. Interestingly, lymphocyte removal remained insignificant, which suggests a highly specific immunomodulatory action.

Impact on the Neutrophil-to-Lymphocyte Ratio (NLR)

Besides cell removal, the research highlighted a significant reduction in the neutrophil-to-lymphocyte ratio (NLR). In fact, the rate of NLR change directly correlated with the extent of neutrophil removal. This correlation was particularly strong in blood samples treated with LPS. Therefore, the PMX column neutrophil removal process may offer a dual benefit: clearing circulating endotoxins and recalibrating the systemic inflammatory response. These findings provide a strong hypothesis-generating framework for using PMX columns in diseases where activated neutrophils play a central pathogenic role.

Does the PMX column remove all white blood cells?

No, the PMX column specifically targets activated granulocytes and neutrophils. The study found that lymphocyte levels were not significantly affected, allowing for a targeted immunomodulatory effect.

Why is the removal of CD11b-positive neutrophils important?

CD11b is a marker of neutrophil activation. These activated cells release inflammatory mediators and proteases that can cause tissue damage. Removing them helps dampen the excessive inflammatory response in conditions like sepsis and AE-IPF.

Disclaimer: This content is for informational and educational purposes only... Refer to the latest local and national guidelines for clinical practice.

References

1. Miyamoto Y et al. Removal of activated neutrophils by a polymyxin B-immobilized fiber (PMX) column. Int J Artif Organs. 2026 Apr 04. doi: 10.1177/03913988261429911. PMID: 41934212.

2. Shoji H, Opal SM. Therapeutic rationale for endotoxin removal with polymyxin b immobilized fiber column (PMX) for septic shock. Int J Mol Sci. 2021 Feb 23;22(4):2029. doi: 10.3390/ijms22042029.

3. Kim MJ, et al. Polymyxin B-hemoperfusion in patients with acute exacerbation of idiopathic pulmonary fibrosis: a single-center prospective pilot study. Korean J Intern Med. 2024 May;39(3):458-468. doi: 10.3904/kjim.2024.244.