Monitoring human leukocyte antigen class I molecules by micro-raman spectroscopy at single-cell level

Human leukocyte antigen (HLA) class I molecules are formed by three immunoglobulin-like domains (α1, α2, and α3) once folded by peptide and β ₂-microglobulin show the presence of two α-helix streams and one β-sheet limiting the pocket for the antigenic peptide. The loss of HLA class I expression in tumors and virus-infected cells, on one hand, prevents T cell recognition, while on the other hand, it leads to natural killer (NK) cell mediated cytotoxicity. We propose the possibility of using Raman spectroscopy to measure the relative expression of HLA class I molecules at the single-cell level. Raman spectra are recorded for three cell lines (K562, T2, and T3) and monomers (HLA class I folded, unfolded and peptide+β ₂-microlobulin refolded) using 830 nm laser line. Our data are consistent with the hypothesis that in the Raman spectra, ranging from 1600 to 1800 cm ^-1, the intensity variation of cells associated with HLA class I molecules could be measured.