Which type of lymphocyte is capable of killing tumor cells and infected cells without prior sensitization?

Granzymes are a family of serine proteases that are stored in and secreted from the cytotoxic granules of cytotoxic T lymphocytes (CTL) and natural killer (NK) cells.

They work in synergy with perforin, a pore-forming toxin, to induce apoptosis in target cells.

Perforin is necessary for the delivery of granzyme B to the target cell cytosol where caspase-dependent and -independent pathways to apoptosis are activated.

Perforins (choice A) are pore-forming toxins that work in synergy with granzymes to induce apoptosis in target cells.

Cytokines (choice B) are signaling molecules that regulate immune responses but do not directly induce apoptosis in target cells.

Interferons (choice D) are a type of cytokine that play a role in immune responses but do not directly induce apoptosis in target cells.

Estrogen is a steroid hormone responsible for the development of female secondary sexual characteristics such as breast development, menstrual cycle, and widening of hips.

Choice A, Progesterone, is not the correct answer because it is required to maintain pregnancy and delivery.

Choice B, Testosterone, is not the correct answer because it is a hormone produced by the testes which control the development of male secondary sexual characteristics.

Choice D, FSH (Follicle Stimulating Hormone), is not the correct answer because it stimulates the growth of ovarian follicles in females and regulates spermatogenesis in males.