<prompt> Which interleukin is T-cell growth factor?IL-3IL-7IL-11IL-5  <response>: Ans. is b i.e., IL-7 T-cell growth factors TCGFs are signaling molecules collectively called growth factors which stimulate the production and development of T-cells. A number of them have been discovered, among them many members of the interleukin family IL-2, IL-4, IL-7, IL-9, IL-15 and IL-21. The thymus is one organ which releases TCGFs. 