The high blood lymphocytes or “lymphocytosis”, as it is technically known, is an indication that an infectious or neoplastic process takes place in the body, such as a viral infection, although in more severe cases it can mean a cancer or an autoimmune disorder.
Lymphocytes are one of the different types of “white cells”, in charge of defending the body from external and internal threats, such as infections, foreign bodies, trauma and tumors..
There are several types of lymphocytes, each with a specific task. Most commonly, elevated lymphocytes in the blood correspond to a particular group of these cells depending on what is causing the lymphocytosis..
In general, lymphocytosis is an asymptomatic process in itself, being the symptoms that the patient presents those derived from the condition that afflicts him.
To detect if lymphocyte levels are normal, it is necessary to perform a hematology where not only the total number of white cells are reported, but also the proportion of the different types..
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In normal hematology, the total number of white cells (generally known as “leukocytes”) should be between 7,500 and 10,000 cells per cubic millimeter of blood analyzed..
In adults, of the total white cells no more than 35-27% correspond to lymphocytes, between 55 and 60% are neutrophils, and the remaining percentage is divided between eosinophils and monocytes (less than 2% each type).
In young children, the ratio of lymphocytes to neutrophils is inverse, which means that around 60% of white cells correspond to lymphocytes and around 40% to leukocytes..
Lymphocytosis is said to exist when one of the following conditions occurs:
- The total white blood cell count rises with an increase in the percentage of lymphocytes compared to normal, for example: an adult has 12,000 white blood cells with 65% lymphocytes.
- The total white cell count is normal but the relationship between leukocytes and lymphocytes is reversed, for example: an adult patient has 8,600 white cells of which 75% are lymphocytes.
In both cases, the total number of lymphocytes will be higher than normal and it will be necessary to investigate the cause in order to establish the most appropriate treatment..
The causes of high lymphocytes in the blood are multiple and very varied, however for practical purposes they can be divided into two large groups:
- Infectious causes
- Tumor causes
In the first case, the lymphocytes rise as a normal defense response of the body against an infection, usually of viral origin..
When this happens, the lymphocytes are responsible for directly destroying the viruses and releasing the antibodies that will help chemical immunity..
On the other hand, when the cause of lymphocytosis is a tumor, it is a type of hematological cancer, in which the lymphocytes grow in an exaggerated and uncontrolled way.
In these cases, the excess of lymphocytes generates serious problems that can compromise the life of the patient..
White blood cells rise in response to infections, however since each type of white blood cell has a specific function, each series rises in response to a particular type of infection..
Thus, neutrophils are the white blood cells that rise in most bacterial infections, while lymphocytes remain within a normal range..
On the contrary, in the vast majority of viral infections the neutrophils remain unchanged, the lymphocytes being the ones that rise.
In this way, we have a wide range of viral infections with elevated lymphocytes. Among the most common infectious causes of elevated blood lymphocytes are:
- Infectious mononucleosis
- Cytomegalovirus infection
- Viral Hepatitis
- Herpesvirus infection (chickenpox)
- Viral rash infections (rubella, measles, viral mumps)
- Influenza and parainfluenza virus infection
In general, the elevation of lymphocytes in the blood secondary to viral diseases is transient, and the values return to normal once the infectious process resolves.
It is important to note that even when viral infections are responsible for lymphocytosis, in the vast majority of cases there are other non-viral infections that can occur with elevated blood lymphocytes.
Non-viral infections associated with lymphocytosis include tuberculosis, toxoplasmosis, brucellosis, and even malaria (malaria).
In all these cases the lymphocytosis disappears once the responsible disease is treated.
The goal of lymphocyte elevation in all infections is to defend the body against infection, either by destroying infectious agents (the responsibility of Killer T lymphocytes) or by releasing antibodies (B lymphocytes)..
Unlike what happens in viral diseases, when lymphocytes rise due to neoproliferative disease (cancer), they do so in a sustained manner.
In some cases, the lymphocytes rise and remain at a given level for a long time (for example, the number of lymphocytes rises to 22,000 and remains stable), while in others they tend to rise constantly reaching levels much higher than normal ( 50,000, 60,000, 80,000 lymphocytes per cubic millimeter of blood and even more).
In both conditions, a hematological neoplasm should be considered as responsible for the elevation of lymphocytes in the blood. These neoplasms are divided into two large groups: lymphoma and leukemia..
Lymphomas are solid neoplasms that affect the lymph nodes. Since the main cellular component of the lymph nodes are lymphocytes in different stages of maturation, patients with lymphoma have an increased number of circulating lymphocytes in the blood.
Of these lymphocytes, the vast majority are mature forms and their number remains high, but more or less stable at a given level for a long time..
For its part, leukemia is considered a proper hematic neoplasm; does not affect solid organs such as lymph nodes, but rather cells in the bone marrow, where all blood cells originate.
In patients with leukemia, the most common is a pattern of leukocytosis that rises constantly without reaching a ceiling, that is, the lymphocytes rise without stopping, usually at the expense of immature forms.
Leukemia is named after the predominant cell type. Thus, there are:
- Myelogenous leukemia (LM)
- Chronic myeloid leukemia (CML)
- Acute myeloid leukemia (AML)
- Chronic lymphoid leukemia (CLL)
- Acute lymphoid leukemia or acute lymphoblastic leukemia (ALL)
The differentiation of the type of leukemia is based on laboratory studies (flow cytometry), since clinically it is almost impossible to distinguish one from the other.
Elevated lymphocytes in the blood do not produce symptoms by themselves, on the contrary, they are part of a syndromic complex that can be accompanied by various symptoms depending on the clinical condition to which the leukocytosis is associated.
In cases of infectious diseases, it is common for the patient to present general symptoms such as general malaise, asthenia (lack of energy or weakness), fever (body temperature above 38.5 ºC), joint and muscle pain.
Depending on the type of viral infection, there may be associated clinical signs such as hepatomegaly (enlargement of the liver, painful or not), splenomegaly (enlargement of the spleen) and lymph nodes (palpable lymph nodes).
In the case of exanthematic viral diseases, the typical rash will appear every few days after the onset of fever and lymphocytosis.
On the other hand, in patients affected by influenza or parainfluenza viruses, the symptoms are, in most cases, very similar to those of the common cold..
In the case of patients with lymphocytosis due to neoplasms, the symptoms are usually general and nonspecific, raising the suspicion of this type of disease either due to the duration of the symptoms (they exceed 7 to 10 days after a viral infection) or due to to findings in laboratory tests.
In general, the symptoms that accompany the elevation of lymphocytes in the blood due to neoplastic disease are fever (without identified infectious focus), weight loss, asthenia (generalized weakness), hyporexia (lack of appetite) and in some cases tendency bleeding or bruising from minor trauma.
In the clinical evaluation of the patient, it is common to detect growth of the liver, spleen or lymph nodes, however clinically there is no way to know if this growth is due to a viral infection or a neoplasm.
The initial diagnosis of lymphocytosis is given by hematology.
Once it is determined that the lymphocytes are elevated, complementary studies are performed to determine the cause. Such examinations are indicated according to the clinical condition, age group and risk factors of the patient..
In cases of viral diseases, the most common is to reach the final diagnosis through serology studies, while in neoplasms it will be necessary to perform peripheral blood smears, flow cytometry and even lymph node biopsy.
There is no treatment for elevated blood lymphocytes per se, instead the cause of lymphocytosis should be treated.
Symptomatic treatment will be necessary for most viral diseases, since almost all are self-limited and will heal without intervention. When necessary, specific treatment should be started as in the case of hepatitis C.
Likewise, when lymphocytosis is associated with TB, toxoplasmosis, brucellosis or any other type of non-viral infection, it will be necessary to administer antibiotics depending on the causative agent..
Finally, in cases of neoplasms of the hematopoietic system (bone marrow and lymph nodes), it will be necessary to administer an appropriate chemotherapy regimen according to the cell line.
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