Isolation and characterization of granuloma initiation factor.

Area of Science:

• Immunology
• Parasitology
• Biochemistry

Background:

• Schistosoma mansoni egg-induced hepatic granulomas (SMHG) involve complex immune responses.
• The soluble factors driving granuloma formation are not fully understood.

Purpose of the Study:

• To isolate and characterize soluble components from SMHG responsible for inducing granulomatous tissue reactions.
• To investigate the potential role of cyclophilin homologs in granuloma initiation.

Main Methods:

• Fractionation of SMHG using Sephacryl S-300 column chromatography and high-pressure liquid chromatography (HPLC).
• Subcutaneous inoculation of purified fractions into naive mice to assess granuloma formation.
• Amino acid sequencing and immunofluorescence microscopy to identify and localize active components.

Main Results:

• A low molecular weight fraction (23, 20, and 16 kd proteins) induced organized granulomas in mice.
• Further purification yielded three fractions that induced skin granulomas.
• The major 20-kd protein showed N-terminal sequence homology to cyclophilin.
• Antisera reacted with granuloma cells, confirming the component's localization.

Conclusions:

• A low molecular weight soluble fraction of SMHG can induce new granuloma formation when immobilized.
• The granuloma initiation factor is suggested to be a cyclophilin gene family homolog.