Combined immunodeficiency is a condition in which the animal fails to produce functioning

Combined immunodeficiency is a condition in which the animal fails to produce functioning

• A. Plasma cells
• B. B cells
• C. T cells
• D. B and T cells

Answer: (D)

Combined immunodeficiency means the immune system cannot mount both humoral and cellular responses. This happens when the body fails to produce functional B lymphocytes, which are responsible for antibody-mediated (humoral) immunity, and T lymphocytes, which drive cell-mediated immunity. B cells mature into plasma cells that secrete antibodies, so a deficiency there impairs antibody production. T cells coordinate immune responses and destroy infected cells, so their deficiency impairs cell-mediated defenses. If only one arm were affected (for example, issues with plasma cells alone), antibodies might be low but T cell function could remain, which wouldn’t explain a true combined problem. Therefore, the condition involves failure of both B and T lymphocytes, making B and T cells the best answer.

Combined immunodeficiency means the immune system cannot mount both humoral and cellular responses. This happens when the body fails to produce functional B lymphocytes, which are responsible for antibody-mediated (humoral) immunity, and T lymphocytes, which drive cell-mediated immunity. B cells mature into plasma cells that secrete antibodies, so a deficiency there impairs antibody production. T cells coordinate immune responses and destroy infected cells, so their deficiency impairs cell-mediated defenses. If only one arm were affected (for example, issues with plasma cells alone), antibodies might be low but T cell function could remain, which wouldn’t explain a true combined problem. Therefore, the condition involves failure of both B and T lymphocytes, making B and T cells the best answer.