Role of gamma-interferon in antibody-producing responses.

Interferon preparations, especially those containing gamma-interferon (IFN-gamma), have long been known to modulate immune responses. However, because many studies used only partially purified interferons, it has been difficult to separate the immunoregulatory effects of the interferons from those of other biologically active molecules contaminating the preparations. Recently, with the cloning of the interferon genes in mouse and man, it has become possible to use these cloned interferons directly to test their effects in assays other than those involving the protection of cells from viruses. For example, cloned IFN-gamma has been shown to be a potent inducer of Ia antigen expression on macrophages. Similarly, cloned IFN-gamma has been reported to act as a macrophage activation factors, as judged by the ability of activated macrophages to kill tumour cells in vitro. We demonstrate here that cloned murine IFN-gamma can also substitute for a late-acting helper factor which acts synergistically with other helper factors in the stimulation of B-cell antibody responses in vitro.