Secondary immunodeficiency is a disease of the immune system that occurs in children and adults, not associated with genetic defects and characterized by the development of repeated, prolonged infectious and inflammatory pathological processes that are poorly amenable to etiotropic treatment. There are acquired, induced and spontaneous forms of secondary immunodeficiency. Symptoms are caused by a decrease in immunity and reflect a specific lesion of an organ (system). The diagnosis is based on the analysis of the clinical picture and data from immunological studies. Vaccination, substitution therapy, and immunomodulators are used in the treatment.
Secondary immunodeficiency – immune disorders that develop in the late postnatal period and are not associated with genetic defects, occur against the background of initially normal reactivity of the body and are caused by a specific causal factor that caused the development of a defect in the immune system.
The causal factors leading to a violation of immunity are diverse. Among them are long-term adverse effects of external factors (environmental, infectious), poisoning, toxic effects of drugs, chronic psychoemotional overload, malnutrition, injuries, surgical interventions and severe somatic diseases that lead to disruption of the immune system, reduced body resistance, the development of autoimmune disorders and neoplasms.
The course of the disease may be latent (there are no complaints and clinical symptoms, the presence of immunodeficiency is detected only in a laboratory study) or active with signs of an inflammatory process on the skin and subcutaneous tissue, upper respiratory tract, lungs, genitourinary system, digestive tract and other organs. Unlike transient shifts in immunity, with secondary immunodeficiency, pathological changes persist even after the elimination of the causative agent of the disease and the relief of inflammation.
A wide variety of etiological factors, both external and internal, can lead to a pronounced and persistent decrease in the body’s immune defense. Secondary immunodeficiency often develops with general exhaustion of the body. Prolonged malnutrition with a deficiency in the diet of protein, fatty acids, vitamins and trace elements, impaired absorption and breakdown of nutrients in the digestive tract lead to disruption of the maturation of lymphocytes and reduce the body’s resistance.
Severe traumatic injuries of the musculoskeletal system and internal organs, extensive burns, serious surgical interventions are usually accompanied by blood loss (along with plasma, complement proteins, immunoglobulins, neutrophils and lymphocytes are lost), and the release of corticosteroid hormones designed to maintain vital functions (blood circulation, respiration, etc.) is even greater depresses the work of the immune system.
The leading role in the development of secondary immunodeficiency is played by chronic viral infectious diseases (HIV, cytomegalovirus infection, Epstein-Barr viruses and other herpes viruses, less often measles, rubella, viral hepatitis, etc.), causing suppression of cellular and humoral immunity. Bacterial and fungal infections, parasitic diseases have an adverse effect on the immune status.
A pronounced violation of metabolic processes in the body in somatic diseases (chronic glomerulonephritis, renal insufficiency) and endocrine disorders (diabetes, hypo- and hyperthyroidism) leads to inhibition of chemotaxis and phagocytic activity of neutrophils and, as a consequence, to secondary immunodeficiency with the appearance of inflammatory foci of various localization (more often these are pyoderma, abscesses and phlegmons).
Immunity decreases with prolonged use of certain medications that have an overwhelming effect on the bone marrow and hematopoiesis, disrupting the formation and functional activity of lymphocytes (cytostatics, glucocorticoids, etc.). Radiation exposure has a similar effect.
In malignant neoplasms, the tumor produces immunomodulatory factors and cytokines, as a result of which the number of T-lymphocytes decreases, the activity of suppressor cells increases, and phagocytosis is inhibited. The situation is aggravated by the generalization of the tumor process and metastasis to the bone marrow. Secondary immunodeficiency often develops in autoimmune diseases, acute and chronic poisoning, in elderly people, with prolonged physical and psycho-emotional overload.
Clinical manifestations are characterized by the presence in the body of a prolonged, resistant to etiotropic therapy, chronic infectious purulent-inflammatory disease against the background of a decrease in immune protection. In this case, the changes may be transient, temporary or irreversible. There are induced, spontaneous and acquired forms of secondary immunodeficiency.
The induced form includes disorders arising from specific causal factors (X-ray radiation, prolonged use of cytostatics, corticosteroid hormones, severe injuries and extensive surgical operations with intoxication, blood loss), as well as severe somatic pathology (diabetes mellitus, hepatitis, cirrhosis, chronic renal failure) and malignant tumors.
In the spontaneous form, the visible etiological factor that caused the violation of immune protection is not determined. Clinically, in this form, there is the presence of chronic, difficult to treat and often aggravated diseases of the upper respiratory tract and lungs (sinusitis, bronchiectasis, pneumonia, lung abscesses), digestive tract and urinary tract, skin and subcutaneous tissue (boils, carbuncles, abscesses and phlegmons), which are caused by conditionally pathogenic microorganisms. Acquired immunodeficiency syndrome (AIDS) caused by HIV infection is isolated in a separate acquired form.
The presence of secondary immunodeficiency at all stages can be judged by the general clinical manifestations of the infectious and inflammatory process. This may be prolonged subfebrility or fever, enlarged lymph nodes and their inflammation, muscle and joint pain, general weakness and fatigue, decreased performance, frequent colds, recurrent sore throats, often recurrent chronic sinusitis, bronchitis, recurrent pneumonia, septic conditions, etc. At the same time, the effectiveness of standard antibacterial and anti-inflammatory therapy is low.
Detection of secondary immunodeficiency requires a comprehensive approach and participation in the diagnostic process of various specialist doctors – allergologist–immunologist, hematologist, oncologist, infectious disease specialist, otorhinolaryngologist, urologist, gynecologist, etc. This takes into account the clinical picture of the disease, indicating the presence of a chronic infection that is difficult to treat, as well as the identification of opportunistic infections caused by opportunistic microorganisms.
It is necessary to study the immune status of the body using all available techniques used in allergology and immunology. Diagnosis is based on the study of all parts of the immune system involved in protecting the body from infectious agents. At the same time, the phagocytic system, the complement system, and subpopulations of T- and B-lymphocytes are studied. Studies are carried out by conducting tests of the first (indicative) level, which allows to identify gross general violations of immunity and the second (additional) level with the identification of a specific defect.
When conducting screening studies (level 1 tests that can be performed in any clinical diagnostic laboratory), you can get information about the absolute number of leukocytes, neutrophils, lymphocytes and platelets (both leukopenia and leukocytosis, relative lymphocytosis, elevated ESR), the level of protein and serum immunoglobulins G, A, M and E occur, hemolytic activity of complement. In addition, it is possible to perform the necessary skin tests to detect delayed-type hypersensitivity.
An in-depth analysis of secondary immunodeficiency (level 2 tests) determines the intensity of phagocyte chemotaxis, the completeness of phagocytosis, subclasses of immunoglobulins and specific antibodies to specific antigens, the production of cytokines, T-cell inducers and other indicators. The analysis of the data obtained should be carried out only taking into account the specific condition of this patient, concomitant diseases, age, the presence of allergic reactions, autoimmune disorders and other factors.
During the examination, differential diagnosis is carried out with primary immunodeficiency, prolonged infectious diseases of viral, bacterial, fungal and parasitic nature, somatic diseases, endocrine disorders, neoplasms.
The effectiveness of the treatment of secondary immunodeficiency depends on the correctness and timeliness of the identification of the etiological factor that caused the appearance of the defect of the immune system and the possibility of its elimination. If a violation of immunity has arisen against the background of a chronic infection, measures are taken to eliminate foci of inflammation using antibacterial drugs, taking into account the sensitivity of the pathogen to them, conducting adequate antiviral therapy, using interferons, etc. If the causal factor is malnutrition and vitamin deficiency, measures are being taken to develop a proper diet with a balanced combination of proteins, fats, carbohydrates, trace elements and the necessary caloric content. Also, the existing metabolic disorders are eliminated, the normal hormonal status is restored, conservative and surgical treatment of the underlying disease (endocrine, somatic pathology, neoplasms) is carried out.
An important component of the treatment of patients with secondary immunodeficiency is immunotropic therapy using active immunization (vaccination), substitution treatment with blood preparations (intravenous plasma, leukocyte mass, human immunoglobulin), as well as the use of immunotropic drugs (immunostimulators). The expediency of prescribing a particular remedy and the selection of dosage is carried out by an allergist-immunologist, taking into account the specific situation. With the transient nature of immune disorders, timely detection of secondary immunodeficiency and the selection of the right treatment, the prognosis of the disease may be favorable.