What Is Primary Immunodeficiency?

1. Diseases dominated by humoral immune (B-cell) deficiency are manifested by a decrease or lack of immunoglobulin.

Primary immunodeficiency disease

Primary immunodeficiency disease is a rare group of diseases that is genetically related. It often occurs in infants and young children. It has repeated infections and is seriously life-threatening. Because some of them may be treated effectively, timely diagnosis is still important. According to the different nature of immunodeficiency, it can be divided into three major categories: humoral immunodeficiency, cellular immunodeficiency and combined immunodeficiency. In addition, non-specific immune defects such as complement defects and phagocytic defects also belong to this group. The exact incidence of various types of primary immunodeficiency diseases in China is unclear, and the relative incidence is roughly 50% of humoral immune deficiency, 10% of cellular immune deficiency, 30% of combined immune deficiency, 6% of phagocytic function deficiency, complement Defect 4%.

Types and examples of primary immunodeficiency diseases

Humoral immunodeficiency

1. Diseases dominated by humoral immune (B-cell) deficiency are manifested by a decrease or lack of immunoglobulin.

Including: (1) Primary gamma globulin deficiency: There are two types: Bruton type, which is more common, is infantile digammaglobulin deficiency, which is related to the recessive inheritance of X chromosome, which only occurs in boys and is born Onset after six months; Autosomal recessive genotype, both men and women can be affected, can also be seen in the elderly.

(2) Solitary IgA deficiency: This disease is the most common congenital immunodeficiency disease. The patient's serum IgA and mucosal surface secretory IgA (SlgA) are deficient. It can be familial or acquired, the former inherited by autosomal recessive or dominant. Most patients are asymptomatic, and some may have repeated sinus or lung infections and chronic diarrhea and asthma. The incidence of autoimmune and allergic diseases is also high.

(3) Common variable immunodeficiency disease: Common variable immunodeficiency is a common and unclearly understood group of syndromes. Both men and women can be affected, ranging from 15 to 35 years of age, and can be congenital or acquired. The scope of the immune deficiency can vary with the stage of the disease. Hypoglobulinemia is present at the onset of the disease, and cellular immunodeficiency can be complicated with the progression of the disease.

Primary immunodeficiency cell immunodeficiency

2. Diseases that are predominantly of cellular immune (T cell) deficiency are more common in simple T cell immune deficiency, which are often accompanied by varying degrees of humoral immune deficiency. This is because normal antibody formation requires the cooperation of T and B cells. The occurrence of T-cell immunodeficiency is related to thymic dysplasia, so it is also called thymic dysplasia or Di George syndrome. This disease is related to the developmental defects of the pharyngeal sac in the third and fourth stages of the embryo. Therefore, patients often have thymus and parathyroid gland absent or underdeveloped, and congenital cardiovascular abnormalities (aortic constriction, right aortic arch deformity, etc.) And other face and ear deformities. T cells are reduced or absent in the peripheral blood circulation, and the number of plasma cells in lymphoid tissues is normal, but lymphocytes in the paracortical thymus-dependent area and around the splenic arterial sheath are significantly reduced.

Primary immunodeficiency disease

3. Combined immunodeficiency disease

(1) Severe combined immunodeficiency disease: This disease is a disease with severe defects in humoral immunity and cellular immunity. Generally, T cell immune deficiency is more prominent.

(2) Immune deficiency disease with thrombocytopenia and eczema: This disease is also known as Wiscott-Aidrich syndrome. It is a recessive inherited immunodeficiency disease of the X chromosome, which is more common in boys. The clinical manifestations are eczema, thrombocytopenia, and repeated infection .

(3) Immunodeficiency disease with ataxia and telangiectasia: This disease is an autosomal recessive genetic disease that often affects young children and has T and B cell immune deficiency.

Phagocytic dysfunction of primary immunodeficiency disease

4. Phagocytic dysfunction

The disease manifests as a decrease in the number of phagocytic cells, a migration dysfunction, and a normal phagocytic capacity, but the ability to kill and digest pathogens is lost due to the lack of various enzymes that digest pathogens in the cell. Patients are susceptible to both pathogenic and non-pathogenic microorganisms, so they are prone to repeated infections. Chronic granulomatosis is a recessive genetic disorder of the X chromosome, which usually starts around the age of 2 and manifests as cervical lymph nodes, skin, Chronic suppurative inflammation or granulomatous inflammation of the lungs, bone marrow, etc., and enlarged liver and spleen.

Primary immunodeficiency disease complement deficiency

5. Complement defect

Complement plays an important role in inflammation and immune response. Common complement defects include lack of C3 or lack of C3 inhibitors. The latter causes excessive consumption of C3 and also decreases C3 levels in serum, leading to repeated bacterial infections. C1 inhibitor is defective. C1 inhibitor is a glycoprotein in serum. In addition to its inhibitory effect on Cis, it can also inhibit the activation of inflammatory mediators such as plasminogen and kinin. Therefore, the deficiency of C1 inhibitor can lead to Increased vascular permeability and tissue edema, so-called hereditary angioedema.