Which interleukin is primarily responsible for T-cell proliferation and is a key mediator of adaptive immune responses?

Interleukin-2 (IL-2) is the primary cytokine responsible for T-lymphocyte proliferation and differentiation. It is produced by activated CD4+ T-helper cells and acts in an autocrine and paracrine manner to drive clonal expansion of T-cells after antigen recognition. IL-2 is critical for the adaptive immune response, including cytotoxic T-cell responses against virally infected cells. IL-1 is a pro-inflammatory cytokine produced by macrophages. IL-6 promotes acute phase response and B-cell differentiation. IL-10 is an anti-inflammatory cytokine that downregulates immune responses.