Severe combined immunodeficiency (SCID) is a pathology that is known as bladder syndrome because sick people are highly vulnerable to infectious diseases and must be kept in a sterile environment. This ailment is the result of severe damage in the immune system, so the latter is considered practically absent.
This disease, which belongs to the category of primary immunodeficiencies and is caused by multiple molecular defects, leading to the disruption of the functions of T cells and B cells. Sometimes the functions of killer cells are disrupted. In most cases, the disease is diagnosed before the age of 3 months from birth. And without the help of doctors, such a child is very rarely able to live more than two years.
About the disease
Every two years, experts of the World Health Organization very carefully review the classification of this disease and are consistent with modern methods of control relating to disorders of the immune system and immunodeficiency states. Over the past few decades, they have identified eight classifications of the disease.
Severe combined immunodeficiency is pretty well studied in the world, and yet the survival rate of sick children is not very high. Here, accurate and specific diagnostics are important, which will take into account the heterogeneity of the pathogenesis of immune disorders. However, it is often carried out either in an incomplete volume, or late, with a great delay.
Typical infections and skin diseases are the most common signs of severe combined immunodeficiency. We will consider the reasons below. It is precisely they that help in the diagnosis of children.
Given that in recent years, advances in gene therapy and the potential for bone marrow transplantation have advanced far, patients with SCID have a good chance of developing a healthy immune system and, as a result, hope for survival. But still, if a serious infection is rapidly developing, the prognosis is often unfavorable.
Causes of the disease
The main reason for severe combined immunodeficiency is mutations at the genetic level, as well as naked lymphocyte syndrome, and tyrosine kinase deficiency.
These causes include infections such as hepatitis, pneumonia, parainfluenza, cytomegalovirus, respiratory syncytial virus, rotavirus, enterovirus, adenovirus, herpes simplex virus, chickenpox, Staphylococcus aureus, enterococci and streptococci, Pseudomonas aeruginosa. Fungal infections also cause predisposition: biliary and renal candidiasis, Candida albicans, legionella, moraxella, listeria.
Many of these pathogenic factors are also present in the body of an absolutely healthy person, but in the formation of adverse conditions, a situation may occur when the protective properties of the body decrease, which, in turn, will provoke the development of immunodeficiency states.
Aggravating factors
What can provoke severe combined immunodeficiency? The presence of maternal T cells in sick children. This fact can cause reddening of the skin with T-cell infiltration, an increase in the amount of liver enzyme. Inadequately, the body can also respond to an inappropriate bone marrow transplant, a blood transfusion that differs in parameters. Signs of rejection include: destruction of biliary epithelium, necrotic erythroderma on the intestinal mucosa.
In previous years, newborns were vaccinated with vaccinia virus. In this regard, children with severe immunodeficiency were dying. To date, the BCG vaccine, which contains the bacillus of Calmette-Guerin, is used worldwide, but it is often the cause of death of children with this disease. Therefore, it is very important to remember that live vaccines (BCG, chickenpox) are strictly forbidden to patients with SCID.
Main forms
Severe combined immunodeficiency in children is a disease characterized by an imbalance of T and B cells, resulting in reticular dysgenesis.
This is a rather rare bone marrow pathology, which is characterized by a decrease in the number of lymphocytes and a complete absence of granulocytes. It does not affect the production of red blood cells and megakaryocytes. This disease is characterized by the underdevelopment of secondary lymphoid organs, and is also a very severe form of SCID.
The reason for this dysgenesis is the inability of granulocyte precursors to form healthy stem cells. Therefore, the functions of hematopoiesis and bone marrow are distorted, blood cells can not cope with their function, respectively, the immune system can not protect the body from infections.
Other forms
Other forms of SCID include:
- Alpha-1 antitrypsin deficiency. The lack of T cells, and, as a consequence, the lack of activity in B cells.
- Adenosine deaminase deficiency. The lack of this enzyme can lead to an excessive accumulation of toxic metabolic products inside the lymphocytes, which causes cell death.
- Deficiency of gamma chains of the T-cell receptor. It is due to a gene mutation on the X chromosome.
- Janus kinase-3 deficiency, CD45 deficiency, CD3 chain deficiencies (combined immunodeficiency, in which mutations occur in genes).
Among doctors there is an opinion that there is a certain group of unrecognized immunodeficiency states.
The causes and symptoms of severe combined immunodeficiency are often interrelated.
However, there are a number of rare genetic diseases of the immune system. These are combined immunodeficiencies. They have less severe clinical manifestations.
Patients with this form of deficiency are helped by bone marrow transplantation from both relatives and from extraneous donors.
Manifestations of the disease
These conditions are characterized by the following manifestations:
- Severe infections (meningitis, pneumonia, sepsis). At the same time, for a child with a healthy immune system, they may not pose a serious threat, while a child with a severe combined ID (TKID) carries a mortal danger.
- Manifestations of inflammation of the mucous membranes, enlarged lymph nodes, respiratory symptoms, cough, wheezing.
- Impaired renal and liver function, skin lesions (redness, rash, ulcers).
- Thrush (fungal infections of the genitals and oral cavity); manifestations of allergic reactions; enzymatic disorders; vomiting, diarrhea; poor blood test results.
It is becoming increasingly difficult to diagnose severe immunodeficiency, since the use of antibiotics is very widespread, which in turn, as a side effect, tends to change the nature of the course of the disease.
The treatment of severe combined immunodeficiencies is presented below.
Therapies
Since the bone marrow transplantation is the basis for the treatment of such severe immunodeficiencies, other treatment methods are practically ineffective. Here it is necessary to take into account the age of patients (from the moment of birth to two years). Children must be given attention, show love, affection and care for them, create coziness and a positive psychological climate.
Family members and all relatives should not only support such a child, but also maintain friendly, sincere and warm relations within the family. Isolation of sick children is unacceptable. They should be at home, within the family, while receiving the necessary supportive care.
Hospitalization
Hospitalization is required in the presence of severe infections, or if the condition of the child is unstable. In this case, it is necessary to exclude contact with relatives who have recently suffered from chicken pox or any other viral diseases.
It is also necessary to observe strict personal hygiene rules for all family members who are near the child.
Stem cells for transplantation are obtained mainly from bone marrow, but in some cases, cord blood and even peripheral blood from related donors may be suitable for this purpose.
The ideal option is a sibling of a sick child. But transplants can also be successful from “related” donors, that is, mother or father.
What does the statistics say?
According to statistics (over the past 30 years), the overall survival rate of patients after surgery is 60-70. More likely to succeed if the transplant is carried out in the early stages of the development of the disease.
Operations of this kind should be carried out in specialized medical institutions.
So, the article examined severe combined immunodeficiency in a child.