Effects of the phenotypic polarization state of human leukocytes on the optical absorbance spectrum

• Published in: Journal of biophotonics Vol. 14; no. 6; pp. e202000487 - n/a
• Main Authors: de Brito Sousa, Kaline, de Fátima Teixeira da Silva, Daniela, Rodrigues, Maria Fernanda Setúbal Destro, Garcia, Mónica Pereira, de Oliveira Rodini, Carolina, Mesquita‐Ferrari, Raquel Agnelli, Hamblin, Michael R, Bussadori, Sandra Kalil, Nunes, Fabio Daumas, Fernandes, Kristianne Porta Santos
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY‐VCH Verlag GmbH & Co. KGaA 01.06.2021; Wiley Subscription Services, Inc
• Subjects: Absorbance; Immunoregulation; Inflammation; Leukocytes; Leukocytes (neutrophilic); Light therapy; Lipopolysaccharides; Lymphocytes; Monocytes; Neutrophils; optical absorbance; Phenotypes; photobiomodulation; Polarization; Wavelengths; photobiomodulation; monocytes; leukocytes; lymphocytes; optical absorbance; neutrophils
• ISSN: 1864-063X; 1864-0648; 1864-0648
• DOI: 10.1002/jbio.202000487

This study evaluated the optical absorbance spectrum of human monocytes, neutrophils and lymphocytes polarized, or not, to the inflammatory or immunoregulatory phenotypes. Peripheral human blood leukocytes were isolated and polarized (10 ng/mL) with LPS or IL‐4 + LPS for 2 hours. After polarization, cells were washed and incubated for an additional 24 hours (monocytes and lymphocytes) or 12 hours (neutrophils). Next, cells were collected to evaluate the optical absorbance spectrum. The three types of leukocytes exhibited absorbance in the region from 450 to 900 nm, with greater absorbance at wavelengths lower than 570 nm. Lymphocytes had a second region of greater absorbance between 770 and 900 nm. Inflammatory monocytes and lymphocytes showed increased absorbance of blue, green and yellow wavelengths (monocytes), as well as red and infrared wavelengths (monocytes and lymphocytes). Immunoregulatory polarization altered the absorbance of monocytes and lymphocytes very little. Neutrophils treated with LPS or LPS + IL‐4 exhibited lower absorbance at wavelengths higher than 575 nm compared to untreated cells. The present findings showed that leukocytes exhibit greater absorbance in regions of the spectrum that have not been much used in photobiomodulation (PBM), and the polarization of these cells can affect their capacity to absorb light. Taken together, these results suggest new perspectives in the use of PBM in the clinical setting depending on the wavelengths and the stage of the inflammatory process. The effects of photobiomodulation (PBM) depend on the absorption of light by chromophores. We showed that leukocytes exhibit greater absorbance in regions of the spectrum that have not been commonly used in PBM, and the polarization of these cells affects their capacity to absorb light. Thus, combining wavelengths in specific periods of the inflammatory process may be considered, not forgetting that light transmission is highly dependent on wavelength.