The identification of cell surface antigens by Lloyd J. Old marked a pivotal moment in immunology and cell biology. Conducted at New York University Medical Center, Old's research focused on isolating proteins found on the cell membranes of various cells, which could then be used to differentiate one cell type from another. This was a significant breakthrough given the limited understanding of cell interactions at the time. By discovering these antigens, researchers gained crucial insights into the mechanisms of the immune system and how it identified and attacked foreign cells, including cancerous ones.

Old's work involved both the utilization of serological techniques to identify these antigens and experimentation with tumor models to observe the immune responses. His research indicated that certain antigens were expressed in specific types of tumors, suggesting that immune response could be harnessed for cancer treatment. This led to the eventual development of targeted therapies and vaccines, marking a notable shift towards precision medicine in oncology.

The identification of these antigens not only enriched the scientific understanding of cellular biology but also provided a framework for future research in vaccine development and immunotherapy. This was crucial in pioneering techniques for diagnosing diseases based on the identification of unique markers on cell surfaces, paving the way for numerous advancements in medical science.