Which of the following is NOT a step used by cytotoxic T cells to kill infected host cells?

-Secretion of granzyme

-Recognition of infected host cell using its TCR

-Recognition of infected host cell using its CD4 glycoprotein

-Secretion of perforin

Answer: Recognition of infected host cell using its CD4 glycoprotein

Explanation: Most cytotoxic T cells express T-cell receptors (TCRs) that can recognize a specific antigen on host cells. This is usually the first step in the destruction of infected host cells. This is followed by the release of two cytotoxic proteins that were earlier formed. First of which is the perforin which creates holes or pores in the membrane of target cells. Next comes the granzymes that induces cell death (apoptosis)