Receiving a blood test result with terms like “high neutrophils” and “low lymphocytes” can be confusing. These are two types of white blood cells that play distinct roles in the body’s immune system. Their levels, when viewed together, offer a snapshot of the body’s current state. This article will explain the functions of neutrophils and lymphocytes, what it might mean when their levels are simultaneously high and low, and why this result warrants a discussion with a healthcare provider.
Understanding Neutrophils and Lymphocytes
Neutrophils are the most abundant type of white blood cell and are the immune system’s “first responders.” When pathogens enter the body or an injury occurs, they are among the first cells to travel to the site. Their primary job is to engulf and destroy invading microorganisms through phagocytosis. They also release enzymes and antimicrobial proteins to kill pathogens directly. Neutrophils produce chemical signals, known as cytokines and chemokines, which help recruit and activate other immune cells, making them a part of the innate immune system.
In contrast to neutrophils, lymphocytes are the specialists of the immune system and are central to the adaptive immune response, a targeted and long-lasting defense mechanism. The two main types are B-cells and T-cells, which work together to eliminate specific pathogens like viruses.
B-cells are responsible for humoral immunity. When they identify a foreign antigen, they transform into plasma cells and produce antibodies that circulate in the blood. These antibodies attach to pathogens, neutralizing them or marking them for destruction. T-cells are in charge of cell-mediated immunity, with some cells directly killing infected or cancerous body cells, while others coordinate the overall response. Both B-cells and T-cells can also form “memory cells” after an infection, allowing the immune system to respond more quickly to the same pathogen in the future.
The Significance of the Combined Pattern
Observing high neutrophils alongside low lymphocytes provides more information than looking at each value in isolation. This combination suggests an immune system under physiological stress, mobilizing its immediate-response forces while specialized immunity is suppressed. The body’s reaction to a severe threat often involves a surge in neutrophil production from the bone marrow. At the same time, the body releases stress hormones, such as cortisol, which can cause a temporary decrease in circulating lymphocytes, a condition known as lymphopenia.
This dynamic has led medical professionals to use the Neutrophil-to-Lymphocyte Ratio (NLR). The NLR is determined by dividing the neutrophil count by the lymphocyte count from a blood test. It serves as a marker of systemic inflammation and physiological stress. A high NLR indicates an emergency-like response where immediate defense takes precedence over the functions of the adaptive immune system.
Potential Causes of High Neutrophils and Low Lymphocytes
Acute Infections
One of the most frequent reasons for a high neutrophil and low lymphocyte count is a significant infection. Severe bacterial infections, such as pneumonia or sepsis, trigger a massive release of neutrophils from the bone marrow to fight the invading bacteria, causing a sharp rise in their numbers. Certain viral infections like influenza and COVID-19 can also produce this pattern. Viruses can lead to a drop in lymphocyte counts because the cells may be heavily recruited to the site of infection or their production may be suppressed.
Inflammation and Tissue Injury
Significant physical trauma or tissue damage can also cause a high neutrophil-to-lymphocyte ratio. Events such as an accident, extensive surgery, a heart attack, or severe burns are perceived by the body as injuries. In response, the immune system initiates an inflammatory cascade to clear out damaged cells and begin the repair process, which involves a surge in neutrophil production. The accompanying physiological stress contributes to the drop in lymphocyte levels, reflecting the body’s focus on crisis management.
Medications
The use of certain medications can also cause this blood count pattern. Corticosteroids, such as prednisone, are well-known for this effect. These drugs are anti-inflammatory agents that mimic the body’s own stress hormones. As a result, they can increase neutrophil levels while decreasing lymphocyte levels, creating the characteristic high NLR pattern.
Some Cancers
Some types of cancer can lead to chronically high neutrophil and low lymphocyte counts. Certain malignancies create a persistent state of inflammation, which signals the immune system to maintain a high level of neutrophils. This sustained inflammatory state, driven by the cancer, can result in an elevated Neutrophil-to-Lymphocyte Ratio. This finding reflects the systemic impact the disease is having on the body, rather than pointing to a specific cancer type.
Next Steps and Medical Interpretation
A lab result showing high neutrophils and low lymphocytes is a data point, not a diagnosis. A physician interprets this finding within the context of a person’s health, symptoms, and medical history. This pattern is a clue that prompts a more thorough investigation to identify the underlying cause. The first step is to review the complete blood count (CBC) panel and conduct a physical examination.
Follow-up tests may be ordered, such as a C-reactive protein (CRP) test to quantify inflammation, blood cultures for infection, or imaging studies like X-rays or CT scans. Medical treatment is directed at the underlying condition, not the blood counts. As the underlying problem is treated, the neutrophil and lymphocyte levels will return to their normal ranges. Discussing these results with the healthcare provider who ordered the test is the necessary next step.