T-Helper Cells' Role in Immune Activation

Steps:

• T-helper cells (CD4+ T cells) coordinate adaptive immunity by releasing cytokines.
• They directly activate B-lymphocytes to differentiate into plasma cells for antibody production.
• They also assist cytotoxic T cells (T-killers) in targeting infected cells.
• Reduced T-helper cells impair these activations, weakening humoral and cellular responses.

Why B is correct:

• T-helper cells provide essential signals (e.g., CD40L and cytokines) to activate B-lymphocytes, per immunological definitions of helper T cell function.

Why the others are wrong:

• A: Reduced T-helpers decrease, not increase, cytotoxic T cell activation, leading to less destruction of infected cells.
• C: T-killer activation requires T-helper signals, so it decreases, not increases.
• D: Plasma cell production depends on B-lymphocyte activation by T-helpers, so it decreases.

Final answer: B