This 1972 study compared two distinct types of interferon produced by human lymphocytes in culture. Researchers stimulated lymphocytes with either ultraviolet-irradiated Newcastle Disease Virus (NDV) or antilymphocyte globulin (ALG), and found that while both inducers triggered interferon synthesis, the resulting proteins differed significantly. NDV-induced interferon had a molecular weight of approximately 25,000 daltons and remained stable at pH 2, whereas ALG-induced interferon was larger (50,000 daltons) and was inactivated at acidic pH. The two interferons also displayed different chromatographic properties on DEAE-cellulose columns, suggesting different charge distributions. Enzymatic stability and heat resistance were similar between both types. The researchers proposed distinguishing these as "virus interferon" (from viral infection) and "immune interferon" (from immunological stimulation). They hypothesized that immune interferon synthesis requires cell-to-cell contact, as evidenced by agglutination during ALG stimulation, whereas virus interferon induction does not. The study suggests immune interferon is likely synthesized by thymus-derived T cells based on available experimental evidence.

Key findings

• ALG-induced lymphocyte interferon (50,000 Da) differs structurally from NDV-induced interferon (25,000 Da)
• ALG-interferon is acid-labile at pH 2 while virus-interferon remains stable, distinguishing immune from viral interferons
• Immune interferon induction requires cell-to-cell contact and agglutination, unlike virus-induced interferon
• Two functionally distinct interferon types exist with different biochemical properties and induction mechanisms
• Immune interferon is likely synthesized by T lymphocytes based on phytohemagglutinin stimulation patterns