Which diagnostic finding is consistent with X-linked agammaglobulinemia?

Which diagnostic finding is consistent with X-linked agammaglobulinemia?

• A. IgG-normal
• B. B-cells-decreased
• C. IgA-normal
• D. T-cells-decreased

Answer: (B)

X-linked agammaglobulinemia stems from a mutation that blocks B cell maturation, so there are very few mature B cells in the peripheral blood. The diagnostic hallmark is a markedly decreased number of circulating B lymphocytes, which leads to very low levels of all immunoglobulin isotypes (IgG, IgA, IgM) after maternal antibodies wane. T cells are typically normal in both number and function, so a decrease in T cells would not fit this condition. IgG normal or IgA normal would also be inconsistent, because the hallmark is a global deficiency of humoral immunity due to the lack of mature B cells.

X-linked agammaglobulinemia stems from a mutation that blocks B cell maturation, so there are very few mature B cells in the peripheral blood. The diagnostic hallmark is a markedly decreased number of circulating B lymphocytes, which leads to very low levels of all immunoglobulin isotypes (IgG, IgA, IgM) after maternal antibodies wane. T cells are typically normal in both number and function, so a decrease in T cells would not fit this condition. IgG normal or IgA normal would also be inconsistent, because the hallmark is a global deficiency of humoral immunity due to the lack of mature B cells.