Congenital agammaglobulinemia is inherited as an X-linked recessive trait, with the defect lying in the impaired differentiation of pre-B cells into B cells. This disease is only seen in males and is also known as Bruton's disease.

bubble_chart Clinical Manifestations

After 4-6 months of birth, the protective effect of maternal IgG disappears, and severe purulent bacterial infections begin to occur repeatedly, especially upper and lower respiratory tract infections. Common conditions include purulent bronchitis, pneumonia, otitis media, as well as meningitis, osteomyelitis, and suppurative arthritis. However, there is no particular susceptibility to toxins or fungi. The child's lymph nodes are underdeveloped, and the tonsils are small or absent. Despite repeated infections, the lymph nodes and spleen do not enlarge.

bubble_chart Auxiliary Examination

1. The total serum immunoglobulin is less than 250 mg/dl, IgG is less than 200 mg/dl, and IgA, IgM, IgD, and IgE are barely detectable.

2. There is a significant reduction in circulating B cells bearing surface Ig or Ia-like antigens, which differs from common variable immunodeficiency.

3. Absence or very low titers of isohemagglutinins.

4. Extremely low or absent antibody response to vaccination.

5. The lymphocyte count in peripheral blood is normal, with an increased percentage of T cells and very few (<0.5%) or absent B cells. The T/B cell ratio is elevated.

6. Cellular immune function is normal.

Lymph node and tonsil biopsy: Absence of germinal centers and plasma cells (while the bone marrow contains a normal number of pre-B cells).

bubble_chart Treatment Measures

The principle is to use replacement therapy to supplement the antibodies that the patient cannot produce. The method involves periodic intramuscular injections of human serum immunoglobulin, with a dose of 0.7 ml/kg of gamma globulin per month. Normal serum IgG is approximately 12.0 g/L. Although this regimen can only maintain the patient's serum IgG at a level of 2.0 g/L, it has a significant therapeutic effect. Long-term repeated injections may cause local scar formation at the injection site, and occasionally fever, rash, urticaria, asthma, and shock-like reactions such as a drop in blood pressure, which should be promptly treated as anaphylactic shock. For patients who do not respond to intramuscular gamma globulin or cannot tolerate the pain, continuous intravenous infusion of plasma at 10 ml/kg can be administered to increase serum immunoglobulin levels. Additionally, intravenous immunoglobulin infusion of 600 ml/kg per month may be given; administering antihistamines or hydrocortisone before the infusion can significantly reduce the side effects of the globulin^[7]

bubble_chart Differentiation

1. Transient hypogammaglobulinemia of infancy: ①Serum IgG is very low, while IgA and IgM are normal. ②The B-cell count in peripheral blood is normal. ③Lymph node biopsy shows plasma cell-like lymphocytes despite the absence of mature plasma cells. ④The ability to synthesize immunoglobulins usually recovers within 18 months.

2. Normal infants aged 5-9 months: ①Although serum IgG is low, it is higher than 350mg/dl. ②IgM and IgA can be detected in serum.