Which of the following Interleukin is raised in a fever?
i.e., TNF-α 
“IL-1 and TNF-α are the two most important pyrogens” — Physiology basics.
Pyrogens

Pyrogens are substances that cause fever.
Pyrogens may be exogenous or endogenous

a) Exogenous → Bacterial toxins
b) Endogenous → IL-1, TNF-a, IL-6, Interferons, Ciliary neurotrophic factor

These pyrogens increase the level of PGE2 in the hypothalamus that elevates the thermoregulatory set point and causes fever.
IFN-γ
TNF-α
IL-10
IL-2