Final answer:
Drugs designed to inhibit T-cell action include immunosuppressants like cyclosporine to prevent organ rejection, and antiretrovirals such as reverse transcriptase inhibitors, integrase inhibitors, protease inhibitors, and fusion inhibitors to treat HIV infections.
Step-by-step explanation:
Drugs that are designed to inhibit the action of T-cells are mainly used in the context of preventing organ transplant rejection and treating certain viral infections, such as HIV. The drug cyclosporine is an example of an immunosuppressive medication that suppresses the immune system by inhibiting the production of interleukin-2, a cytokine critical for T-cell growth and activity. In the realm of antiviral drugs, particularly those targeting HIV, several classes of medications disrupt various phases of the viral life cycle, which indirectly affects T-cell function by preventing the virus from using the cells to replicate. These include reverse transcriptase inhibitors (e.g., AZT), which block the conversion of viral RNA to DNA; integrase inhibitors, which prevent the integration of viral DNA into the host genome; protease inhibitors, which block viral protein processing; and fusion inhibitors, which prevent the virus from entering the T-cells.