An immune state of patient is the first question in medicine. The fluorescent probe offers clinicians a quick, reliable, and reproducible method. The material is presents findings of investigating the possibility of using the original fluorescent probe ABM (an aminoderivative of benzanthrone) for the detection of structural/functional alterations in blood plasma albumin and among immunocompetent cells in patients with different pathologies (non-malignant and malignant). We registered probe ABM spectral parameters in patients lymphocytes, blood plasma, and ABM auto-fluorescence in plasma. The fluorescence intensity of ABM in blood plasma and lymphocyte suspension differed from control values and showed specific differences in patient groups in accordance with immune status of patients. A significant decrease in ABM fluorescence in plasma could be explained, in part, by a diminished binding capacity of the albumin of these patients. The ABM fluorescence in cell suspension and blood plasma was found to correlate with select immunological parameters (CD4+/CD8+ ratious, lymphocyte counts, etc.). There was a strong agreement between changes in ABM spectral parameters and both clinical and pathological estimates of disease severity. Measures of ABM spectral characteristics could potentially be a useful tool to estimate the immune status of patients. Compared to many commonly used diagnostic protocols, the fluorescence based method is sensitive, less expensive and time consuming, technically simple and convenient.