Biochemical relationship between murine immune interferon and a killer cell helper factor

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• Mouse spleen cells stimulated by Concanavalin A or alloantigen release factors enhancing cytotoxic cell generation in vitro.
• Previous studies identified one killer cell helper factor (KHF) associated with thymocyte mitogenic factor (TMF) in cell culture supernatants.

Purpose of the Study:

• To characterize and differentiate the antigen-nonspecific factors released by stimulated mouse spleen cells that enhance cytotoxic cell generation.
• To investigate the relationship between the second KHF and type II interferon.

Main Methods:

• Supernatant analysis using ammonium sulfate fractionation, gel filtration, hydroxylapatite chromatography, and hydrophobic chromatography.
• Assessment of KHF activity and its association with thymocyte mitogenic factor and type II interferon.
• Evaluation of KHF stability following exposure to pH-2 buffer.

Main Results:

• A second KHF was identified, separable from thymocyte mitogenic factor but inseparable from type II interferon.
• This second KHF demonstrated similar sensitivity to pH-2 buffer exposure as immune interferon.
• The combined activity of both KHFs in unfractionated supernatant was additive and greater than individual factors.

Conclusions:

• Mouse spleen cells produce at least two distinct KHFs that independently enhance cytotoxic cell generation.
• One KHF is associated with TMF, and the second KHF is closely linked to type II interferon.
• The additive effects of these two factors contribute to the overall helper activity observed in cell supernatants.