Basophilia (basophilic leukocytosis) is an increase in the content of basophils more than 150 in 1 μl of blood or more than 1% of the total number of leukocytes. It often accompanies eosinophilia, since basophils and eosinophils are jointly involved in many pathological reactions. The causes of basophilia are allergic, inflammatory, oncohematological diseases. There are no specific manifestations, the clinical picture is determined by the underlying pathology. Measurement of the level of basophils is carried out in the general blood test. To eliminate basophilia, it is necessary to treat the disease against which it arose.
An increase in the percentage of basophils with a normal level of leukocytes is called relative basophilia. An increase in the number of basophils along with general leukocytosis is an absolute basophilia. According to the pathogenetic mechanism of development, the following types of basophilia are distinguished:
There is a so-called physiological basophilia, which is not associated with any pathological processes. Most often occurs in women (during pregnancy, during ovulation, and in the middle of the luteal phase of the menstrual cycle), since a high concentration of estrogens causes basophilic leukocytosis. In young children, the cause of simultaneous basophilia and monocytosis is the eruption of milk teeth. Sometimes basophilia occurs during the recovery period from infections (chicken pox, influenza, tuberculosis).
The most common cause of basophilia is IgE-mediated hypersensitivity reactions. Such reactions underlie urticaria, atopic dermatitis, bronchial asthma, etc. When the allergen interacts with IgE receptors on the basophil membrane, they degranulate and release a large amount of histamine, leukotrienes, and interleukins (mediators of allergic inflammation). Basophils also secrete a special protein - an eosinophilic chemotactic factor that stimulates the influx of eosinophils to the site of inflammation. The degree of basophilia is insignificant, it is quickly resolved after the elimination of clinical symptoms.
Another common cause of basophilia, especially among children, is helminthiases: hookworm, ascariasis, and toxocariasis. This is because basophils can cause chemotaxis (targeted movement) of eosinophils, which are the main antiparasitic tool of the immune system. Despite this, basophilia is considered a less sensitive marker of helminthic invasion than eosinophilia. The concentration of basophils increases slightly and only in the acute period (larval migration stage), then returns to normal levels.
Basophilia is often caused by diseases accompanied by inflammation. This mainly concerns autoimmune inflammation of the connective tissue, which is most characteristic of rheumatological pathologies. The exact pathogenetic mechanism of basophilia in these diseases has not been established. In children, basophilic leukocytosis is mainly observed during the active phase of acute rheumatic fever, and in adults - with ulcerative colitis and diffuse connective tissue diseases (systemic lupus erythematosus). Basophilic leukocytosis indicates a very intense inflammatory process in the tissues; during remission, basophils remain within the normal range.
The main cause of high basophilia (up to 4-5%) is recognized oncohematological pathologies, namely, chronic myeloid leukemia, mast cell leukemia (a malignant form of systemic mastocytosis), polycythemia vera (Wakez's disease). The mechanism of basophilic leukocytosis is the tumor (clonal) degeneration of the progenitor cell in the bone marrow and hyperproduction of basophils. A simultaneous increase in basophils with eosinophils (basophilic-eosinophilic association) is one of the laboratory signs of blast transformation of chronic myeloid leukemia (the final stage of the disease, characterized by a very high risk of mortality).
Basophilic leukocytosis. Several basophils in view
To find out the cause of basophilic leukocytosis, you need to contact a medical specialist. The doctor asks the patient if he has recently had an infectious disease or if he suffers from an allergic pathology. If there are any symptoms (joint pain, weight loss, spontaneous bleeding), they must be mentioned. An additional examination is also assigned, including:
A short-term increase in basophils during recovery from an acute viral infection or during pregnancy is a normal and harmless phenomenon that does not require any intervention. Persistent, and even more high (up to 5%) basophilic leukocytosis, requires correction by treating the disease that caused its development.
Basophilia in itself does not bring any harm to health. In some cases, it may be an indicator of a poor prognosis (for example, the sudden onset of basophilia indicates the development of a blast crisis in chronic myelogenous leukemia). However, the prognosis is mainly determined by the underlying disease. Therefore, if basophilic leukocytosis is detected, you should consult a doctor to find out its cause.