A patient with a genetic defect has functional B cells but lacks a thymus. Why does this condition still lead to severely impaired antibody production against T-dependent antigens?

💡 Explanation

T-dependent antigens require T helper cells to activate B cells for antibody production. Because the thymus is essential for T cell maturation, its absence means functional T helper cells will not develop; therefore, B cells cannot receive the necessary signals for activation against these antigens, rather than B-cell intrinsic defects or class-switching impairments directly.

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