| Cytokine | Source | Major Functions |
| Interleukin-1 (IL-1) | Monocytes, macrophages, and other cells | Stimulates T-cell proliferation and IL-2 production |
| Interleukin-2 (IL-2) | Macrophages, T cells, and NK cells | Stimulates proliferation of T cells, B cells, and NK cells; activates monocytes |
| Interleukin-3 (IL-3) | T cells | Acts as growth factor for tissue mast cells and hematopoietic stem cells |
| Interleukin-4 (IL-4) | T cells | Promotes growth of B and T cells; enhances expression of HLA class II antigens |
| Interleukin-5 (IL-5) | T cells | Promotes end-stage maturation of B cells into plasma cells |
| Interleukin-6 (IL-6) | T cells, monocytes, and other cells | Promotes maturation of B and T cells; inhibits growth of fibroblasts |
| Interferon-α (IFN-α) | B cells and macrophages | Has antiviral activity |
| Interferon-β (IFN-β) | Fibroblasts | Has antiviral activity |
| Interferon-γ (IFN-γ) | T cells and NK cells | Has antiviral activity; activates macrophages; enhances expression of HLA class II antigens |
| Tumor necrosis factor α (TNF-α, cachectin) | Macrophages, T cells, and NK cells | Stimulates T-cell proliferation and IL-2 production; cytotoxic to some tumor cells |
| Tumor necrosis factor β (TNF-β) | T cells | Stimulates T-cell proliferation and IL-2 production; cytotoxic to some tumor cells |