Rapid monitoring of T- lymphocyte CD4+/CD8+ ratio in patient immune management by infrared spectroscopy of whole leukocytes

As an essential indicator of human immune status, the T- lymphocyte CD4+/CD8+ ratio can be used to monitor the progression of diverse pathological status, assess the effectiveness of treatment and prognosis. Unfortunately, the conventional method for detecting the T- lymphocyte CD4+/CD8+ ratio is time-consuming and costly. Here, the Fourier transform infrared (FTIR) spectroscopy analysis method was applied to 52 clinical samples of varying immune statuses, revealing the nature of changes in immune status. A fitted model was built using FTIR spectroscopy based on fluorescence activated cell sorting (FACS), providing a correlation formula between the concentration of leukocyte subpopulations and the corresponding infrared spectrum. It was shown that the T- lymphocyte CD4+/CD8+ ratio can be identified from the spectral features of whole leukocyte populations using the principal component analysis- linear discriminant analysis (PCA-LDA) model. To this end, it has been demonstrated that the parameter of β-sheets/α-helix can separate sample sets in normal immune status with 100 % specificity and in abnormal immune status with 92 % sensitivity successfully by fitting protein secondary structures. It's an effective way to rapidly monitor T- lymphocyte CD4+/CD8+ ratio in patient immune management, which improves the effectiveness of clinical decision-making of treatment response. This way may serve as the basis for subsequent direct blood testing, and may be potentially utilized by hospitals in the future.