Lysosomal dysfunction is linked to various diseases, including neurodegenerative, cardiovascular, and cancerous conditions. Damage to the lysosomal membrane, causing lysosomal membrane permeabilization (LMP), can lead to autophagy, inflammation, or cell death. Cytotoxic T lymphocytes (CTLs) exhibit high lysosomal membrane stability and numerous lysosomes per cell, prompting analysis of whether this is due to lysosome quantity or membrane composition. The research aimed to utilize galectin puncta assays, the most sensitive method for LMP detection, on THP-1 and MCF-7 cell lines, as inducing lysosomal damage with LLOMe. We focused on detecting galectin-1 and galectin-3 through indirect immunofluorescence and LAMP-1 and LAMP-2 proteins as lysosomal markers, using confocal microscopy and flow cytometry to visualize and quantify the results. Both THP-1 and MCF-7 cell lines were used as references for these methods, which we plan to apply to CTL cells in the future.