All are true regarding agammaglobulinemia except -a) Loss of germinal centre in lymph nodeb) Normal cortical lymphocytesc) Normal cortical lymphocytes in paracortex and medullad) Decreased red pulp in spleene) Immunodeficiency (cell mediated)
**Core Concept**
Agammaglobulinemia is a primary immunodeficiency disorder characterized by a deficiency in the production of antibodies (immunoglobulins) due to a defect in B-cell development and function. This leads to impaired humoral immunity and increased susceptibility to infections, particularly those caused by encapsulated bacteria.
**Why the Correct Answer is Right**
Agammaglobulinemia is caused by mutations in genes involved in B-cell development, such as BTK (Bruton's tyrosine kinase) or CD19. The absence of germinal centers in lymph nodes is a hallmark of this condition, as germinal centers are crucial for B-cell maturation and antibody production. However, the paracortex and medulla of lymph nodes are not directly affected, as they are primarily involved in T-cell function and other immune processes. Additionally, the spleen's red pulp is not significantly decreased, as this region is involved in filtering the blood and removing old or damaged red blood cells.
**Why Each Wrong Option is Incorrect**
**Option A:** The loss of germinal centers in lymph nodes is a characteristic feature of agammaglobulinemia, making this option incorrect.
**Option B:** Normal cortical lymphocytes are not typically affected in agammaglobulinemia, as the condition primarily affects B-cell development and function.
**Option C:** Normal cortical lymphocytes in the paracortex and medulla are indeed present in agammaglobulinemia, as these regions are involved in T-cell function and other immune processes.
**Option D:** Decreased red pulp in the spleen is not a characteristic feature of agammaglobulinemia, as the condition primarily affects antibody production and B-cell development.
**Clinical Pearl / High-Yield Fact**
Agammaglobulinemia is a classic example of a primary immunodeficiency disorder that affects antibody production, leading to increased susceptibility to infections. It is essential to consider this condition in patients with recurrent infections, particularly those caused by encapsulated bacteria.
**Correct Answer: C. Normal cortical lymphocytes in paracortex and medulla.**