primary immunodeficiencies in adults
Causes and risk factors
In most cases they appear because of a hereditary genetic alteration: the altered gene conditions a defect in the development or maturation of the cells of the immune system or the lack in the blood of a protein of the complement system. The latter system is a set of plasma proteins that enhance the innate immune defense.
More precisely, in the primitive forms of immunodeficiency the defect is of the immune system. In acquired primitive forms, such as the common variable immunodeficiency of the adult, the defect arises in adulthood for reasons not yet clarified.
In the secondary forms, an originally healthy immune system becomes ill following an infection (e.g. from HIV, as in the Acquired Immunodeficiency Syndrome or AIDS) or after treatment with drugs (e.g. with anticancer chemotherapy).
Very rarely the disease can be associated with a thymus neoplasm.
Which are the symptoms?
The most severe congenital forms (severe combined immunodeficiency or SCID, adenosine deaminase deficiency, sex-linked agammaglobulinemia or Bruton's disease) manifest as early as neonatal or early childhood with:
- bacterial infections;
- viral infections;
- repeated fungal and protozoal infections.
They are identified and treated by pediatricians.
Other milder forms such as selective IgA deficiency, certain immunoglobulin subclass deficiencies or myeloperoxidase deficiency may, on the other hand, not significantly compromise the defense capabilities and can only be detected in adulthood.
How is it diagnosed?
The tests necessary to identify an immunodeficiency are the dosage of immunoglobulins and the count of T and B lymphocytes in the blood. In specialized laboratories it is then possible to perform more sophisticated functional tests.
How is it treated?
Primary immunodeficiency therapy is on two levels:
• the treatment of infectious complications with antibiotic therapy;
• the periodic administration of large quantities of human immunoglobulins intravenously.
However, these therapies are not sufficient to guarantee survival in the most severe forms, such as immunodeficiencies with severe combined defect (SCID), which can lead to death in the first few years of life if not corrected. Currently this is only possible through allogeneic bone marrow transplantation. For some forms of SCID, experimental gene therapy has already achieved success.