Interferon induced in human leukocytes by mitogens: production, partial purification and characterization

Area of Science:

• Immunology
• Virology
• Biochemistry

Background:

• Interferons (IFNs) are crucial cytokines involved in antiviral immunity and immune regulation.
• Different types of interferons (alpha, beta, gamma) exhibit distinct properties and functions.
• Induction and characterization of specific interferon types are essential for understanding their therapeutic potential.

Purpose of the Study:

• To investigate the induction and partial purification of gamma-interferon from human leukocytes.
• To characterize the properties of the induced gamma-interferon.
• To evaluate the biological activities of purified gamma-interferon, including its effects on cell growth and natural killer activity.

Main Methods:

• Human buffy coat leukocyte suspensions were stimulated with phytohemagglutinin P, concanavalin A (Con A), and staphylococcal enterotoxin A.
• Antiviral activity was measured, and interferon was partially purified using controlled-pore glass (CPG) beads and ethylene glycol elution.
• Purified interferon was characterized by gel filtration, acid lability, species-specificity, and serological assays.
• Inhibition of lymphoblastoid cell growth and potentiation of natural killer (NK) activity were assessed.

Main Results:

• Concanavalin A rapidly induced high yields of antiviral activity within 12 hours.
• Partial purification yielded a gamma-type interferon with a specific activity of approximately 10^5.3 units/mg protein.
• The purified gamma-interferon exhibited characteristics including a molecular weight of 45,000 daltons, acid lability, and strict species-specificity.
• Crude supernatants also contained beta-interferon-like antiviral activity.
• Purified gamma-interferon inhibited the growth of Daudi and Molt-4 lymphoblastoid cells and potentiated NK activity, comparable to alpha and beta interferons of similar antiviral potency.

Conclusions:

• Concanavalin A is an effective inducer of gamma-interferon from human leukocytes.
• A purification method using CPG and ethylene glycol successfully isolated gamma-interferon with distinct biochemical and biological properties.
• The biological activities of gamma-interferon, including antiproliferative and immunomodulatory effects, are comparable to other interferon types at equivalent antiviral potencies.