Determination of human leukocyte populations involved in production of interferons alpha and gamma.

Human mononuclear leukocyte populations separated into T-, B-, and monocyte-enriched fractions, were evaluated for their abilities to produce interferons when induced with either virus, double-stranded RNA or mitogens. The main producer of alpha-interferon was the B-cell enriched subpopulation, but these cells did not produce gamma-interferon. In contrast, the T-cell enriched population produced either alpha or gamma interferons, depending upon the type of inducer used. The monocyte-enriched population was also able to produce either alpha or gamma interferon. The presence of monocytes in T-cell enriched populations enhanced the levels of alpha interferon production, and removal of monocytes from T-cell enriched populations diminished levels of alpha interferon produced. Even though each of the mononuclear populations (B-, T-, and monocytes) were able to produce alpha-interferon in response to poly rI.polyrC, it was found, by using a single-cell production assay, that only about 0.1% of the total mononuclear population actually produced alpha-interferon when so induced. Similarly, using the single-cell production assay, it was demonstrated that gamma-interferon was produced by only a small proportion of induced T-cells (possibly on T-cell subpopulation), as only about 1 T-cell per 1,000 responded to PHA by production of gamma-interferon.