Lymphocytes: your body's first line of defense
Lymphocytes are immunity sentinels that protect the body and are the basis of new cancer treatment options.
Published on March 13, 2025
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Lymphocytes, a critical type of white blood cell, form the cornerstone of our immune system by recognizing and attacking pathogens. Having a balanced level of them is key to a strong health condition. While high levels might point to infections like mononucleosis, low levels, or lymphocytopenia, could indicate a predisposition to infections and even grave health risks.
Lymphocytes, which form 20% to 40% of white blood cells, are crucial defenders in your body's immune system. These specialized cells develop in the red bone marrow and serve as vigilant protectors against disease and infection. In healthy adults, the normal range typically falls between 1,000 and 4,800 lymphocytes per microliter of blood. Two types of lymphocytes exist: T cells and B cells.
T cells are responsible for your body’s immune system response, attacking and killing directly infected and tumor cells. B cells make antibodies, proteins that target viruses, bacteria, and all other foreign invaders.
When lymphocytes rise concern
Medical experts consider lymphocyte levels concerning when they fall below 1,500 per microliter, known as lymphocytopenia. High levels exceeding 4,000 per microliter may indicate lymphocytosis, often triggered by the body's response to infections or inflammatory conditions. Even seemingly mundane factors like intense exercise or alcohol consumption can affect these numbers.
A Danish study revealed a significant correlation between low lymphocyte counts and increased mortality risk. The research, examining 108,135 individuals between 2003 and 2015, found this association persisted regardless of other risk factors, including age. Common symptoms for individuals experiencing low lymphocyte counts may include frequent or unusual infections, swollen lymph nodes, and joint pain. Importantly, abnormal levels can signal various underlying conditions, from viral infections like COVID-19 to autoimmune disorders like lupus and rheumatoid arthritis.
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Diagnostic approach
Healthcare providers typically assess lymphocyte health through specific tests, including the absolute lymphocyte count and flow cytometry. The latter involves a sophisticated process where blood cells are suspended in fluid and analyzed using laser technology. When examining results, doctors pay particular attention to whether lymphocytes are monoclonal (from a single cell) or multi-clonal (from multiple cells), as this distinction can help differentiate between potential blood cancers and normal immune responses.
Innovators in lymphocytes research
Given lymphocytes' primary role in bolstering the human body’s immunity, innovative companies are developing lymphocyte-based treatment options. An example is Iovance Biotherapeutics. The Californian is pioneering a disruptive approach in cancer care through T-cell-based immunotherapy. The company deploys billions of tumor-infiltrating lymphocyte (TIL) cells to recognize and target cancer cells. As the company performs clinical tests, this therapy potentially applies to several solid tumor types–such as tissues and bones, sarcomas–and to blood cancers.
Similarly, Obsidian Therapeutics is also working on engineered TIL therapies. The company’s proprietary cytoDRIVE platform technology is the tool to leverage drug responsive domains (DRDs) to control protein function. For every protein, Obsidian engineers a ‘gene cassette’ with a DRD tag that is then inserted into the target cell. At the moment, the company is working to offer a therapy solution for melanoma–skin cancer.
Turnstone Biologics is also developing new medicines to treat and cure solid tumors. The company is developing TIL therapies by selecting the most potent–most capable–tumor-reactive T-cells to mediate a response. The Selected TILs approach focuses on selecting and expanding the most potent tumor-reactive T cells to overcome the limitations of bulk TILs.
As lymphocytes therapy research gains momentum, in the future we can expect new care options to arise and provide options to patients worldwide.
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