Interferons

In addition to altering a cell's ability to fight off viruses, interferons also control the activities of a number of specialized cells within the immune system. For example, type I interferons can either inhibit or induce the production of B lymphocytes (white blood cells that make antibodies for fighting disease). Interferon-gamma can also stimulate the production of a class of T lymphocytes known as suppressor CD8 cells, which can inhibit B cells from making antibodies.

Another role of interferon-gamma is to increase immune system functioning by helping macrophages, still another kind of white blood cell, to function. These scavenger cells attack infected cells and also stimulate other cells within the immune system. Interferon-gamma is especially effective in switching on macrophages to kill tumor cells and cells that have been infected by viruses, bacteria, and parasites.

Interferon-tau, first discovered for its role in helping pregnancy to progress in cows, sheep, and goats, also has antiviral qualities. It has been shown to block tumor cell division and may interfere with the replication of the acquired immune deficiency, or AIDS, virus. Since it has fewer unwanted side-effects (flu-like symptoms and decreased blood cell production) than the other interferons, interferon-tau is becoming a new focal point for research.

Commercial fermentation units like these are used to grow cultures of microorganisms for biological products like interferon. Photograph by S. Stammens. National Audubon Society Collection/Photo Researchers, Inc. Reproduced by permission.