Biochemical analysis of leukocytes after in-vitro and in-vivo ac-2 tivation with bacterial and fungal pathogens using Raman 3 spectroscopy
in: International Journal of Molecular Sciences (2021)
Biochemical information from activated leukocytes provide valuable diagnostic infor-27 mation. In this study, Raman spectroscopy was applied as a label-free analytical technique to char-28 acterize the activation pattern of leukocyte subpopulations in an in-vitro infection model. Neutro-29 phils, monocytes, and lymphocytes were isolated from healthy volunteers and stimulated with 30 heat-inactivated clinical isolates of Candida albicans, Staphylococcus aureus, and Klebsiella pneumoniae. 31 Binary classification models could identify the presence of infection for monocytes and lympho-32 cytes, classify the type of infection as bacterial or fungal for neutrophils, monocytes, and lympho-33 cytes and distinguish the cause of infection as Gram-negative or Gram-positive bacteria in the mon-34 ocyte subpopulation. Changes in single-cell Raman spectra upon leukocyte stimulation can be ex-35 plained with biochemical changes due to the leukocyte’s specific reaction to each type of pathogen. 36 Raman spectra of leukocytes from the in-vitro infection model were compared with spectra from 37 leukocytes of patients with infection (DRKS-ID: DRKS00006265) with the same pathogen groups, 38 and a good agreement was revealed. Our study elucidates the potential of Raman spectroscopy-39 based single-cell analysis for the differentiation of circulating leukocyte subtypes and identification 40 of the infection by probing the molecular phenotype of those cells.