Basophilia (basophilic leukocytosis) is an increase in the basophil content of more than 150 in 1 ml of blood or more than 1% of the total number of leukocytes. It is very often accompanied by 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. Basophil levels are measured in a general blood test. To eliminate basophilia, it is necessary to treat the disease against which it arose.
An increase in the percentage of basophils at normal leukocyte levels is called relative basophilia. An increase in the number of basophils along with general leukocytosis is absolute basophilia. According to the pathogenetic mechanism of development , the following types of basophilia are distinguished:
- Reactive. The most common variety. The cause is allergic and inflammatory diseases.
- Neoplastic (malignant). It is associated with oncohematological diseases. High basophilic leukocytosis is characteristic.
Causes of basophilia
There is a so-called physiological basophilia, which is not associated with any pathological processes. It is most often found 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 baby teeth. Sometimes basophilia occurs during recovery from infections (chickenpox, influenza, tuberculosis).
The most common cause of basophilia is IgE-mediated hypersensitivity reactions. Such reactions underlie urticaria, atopic dermatitis, bronchial asthma, etc. When an allergen interacts with IgE receptors on the basophil membrane, their degranulation occurs and a large amount of histamine, leukotrienes and interleukins (mediators of allergic inflammation) are released. Basophils also secrete a special protein – eosinophilic chemotactic factor that stimulates the influx of eosinophils to the focus of inflammation. The degree of basophilia is insignificant, it resolves quickly after the elimination of clinical symptoms.
Another common cause of basophilia, especially among children, is helminthiasis: hookworm, ascariasis, toxocarosis. This is due to the fact that basophils are able to cause chemotaxis (purposeful movement) of eosinophils, which are the main antiparasitic weapon of the immune system. Despite this, basophilia is considered a less sensitive marker of worm infestations than eosinophilia. The concentration of basophils increases slightly and only in the acute period (the stage of larval migration), then returns to normal indicators.
The cause of basophilia is often diseases accompanied by inflammation. This mainly concerns autoimmune inflammation of 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, in adults – with nonspecific 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 normal limits.
Malignant blood diseases
The main cause of high basophilia (up to 4-5%) is recognized as oncohematological pathologies, namely, chronic myeloid leukemia, mast cell leukemia (a malignant form of systemic mastocytosis), true polycythemia (Vakeza disease). The mechanism of basophilic leukocytosis consists in tumor (clonal) degeneration of the progenitor cell in the bone marrow and hyperproduction of basophils. Simultaneous increase of basophils with eosinophils (basophil-eosinophil 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).
- Endocrine disorders: severe hypothyroidism (myxedema).
- Blood diseases: hemolytic anemia, hemophilia.
- Taking medications: estrogen-containing drugs (oral contraceptives).
- Exposure to ionizing radiation.
To find out the cause of basophilic leukocytosis, you need to contact a medical specialist. The doctor asks the patient if he has recently suffered an infectious disease, if he suffers from an allergic pathology. If there are any symptoms (joint pain, weight loss, spontaneous bleeding), they should definitely be mentioned. An additional examination is also prescribed, including:
- Blood tests. The total number of leukocytes and the leukocyte formula is calculated. The concentration of markers of inflammation is determined – ESR, CRP. The ELISA method identifies specific antibodies (IgM, IgG) to helminth antigens. An analysis is carried out for the presence of autoantibodies – antistreptolysin, At to double-stranded DNA. For the diagnosis of chronic myeloid leukemia, the detection of the Philadelphia chromosome using cytogenetic research is informative. Through immunophenotyping of blood cells, tumor CD markers are found.
- Allergodiagnostics. The allergic nature of the disease is confirmed by the high content of immunoglobulin E (IgE) in the blood. To identify the causal (“guilty”) allergen, special skin and provocative tests are carried out – application to the skin, intradermal administration, inhalation of various allergens. Mast cell degranulation tests (direct or indirect) are also performed.
- Instrumental research. For the diagnosis of bronchial asthma, spirometry with a drug test has an important role. With rheumatism, echocardiography shows valve damage, sometimes an effusion into the pericardial cavity. In oncohematological diseases, ultrasound of the abdominal organs reveals hepatosplenomegaly. With ulcerative colitis, hyperemia and ulcerative defects of the mucous membrane are visible on fibrocolonoscopy.
- Histological studies. If a malignant blood disease is suspected, a sternal puncture or trepanobiopsy is necessarily performed to obtain a bone marrow sample. During its microscopic examination, diffuse hyperplasia of the granulocytic germ, a large number of blast cells are noted.
A short-term increase in basophils during recovery from an acute viral infection or during pregnancy is an absolutely normal and harmless phenomenon that does not require any intervention. Persistent, and even higher (up to 5%) basophilic leukocytosis, requires correction by treating the disease that caused its development.
- Anti-allergic treatment. To eliminate allergy symptoms, first of all, maximum restriction of contact with the allergen is recommended, antihistamines (loratadine, cetirizine) and glucocorticosteroids (prednisone) are also used. The method that allows you to completely get rid of allergies is allergen–specific immunotherapy (SIT).
- Deworming. Anthelmintic medications (mebendazole, albendazole) are used for helminthic invasions. Very often, antiallergic agents are additionally prescribed.
- Anti-inflammatory treatment. In autoimmune diseases, medications that suppress the inflammatory process are used – glucocorticoids, immunosuppressants (methotrexate, cyclophosphamide), derivatives of 5-aminosalicylic acid (sulfasalazine), derivatives of aminoquinoline (hydroxychloroquine).
- Treatment of oncohematological diseases. In case of malignant blood diseases, chemotherapy courses are prescribed from a combination of cytostatic drugs (imatinib, vinblastine, vincristine). With true polycythemia, hydroxyurea and alpha-interferon are effective for suppressing pathological hematopoiesis.
Basophilia itself does not cause any harm to health. In some cases, it can be an indicator of an unfavorable prognosis (for example, the sudden occurrence of basophilia indicates the development of a blast crisis in chronic myeloid leukemia). However, the prognosis is mainly determined by the underlying disease. Therefore, if basophilic leukocytosis is detected, you need to consult a doctor to find out its cause.