A low molecular weight proinflammatory factor from rat spleen lymphocytes. Isolation and partial characterization

Area of Science:

• Biochemistry
• Immunology
• Pharmacology

Background:

• Proinflammatory mediators play a crucial role in inflammatory responses.
• Low molecular weight factors from lymphocytes are implicated in immune modulation.
• Understanding the chemical nature of such factors is key to elucidating inflammatory pathways.

Purpose of the Study:

• To isolate and partially characterize a novel low molecular weight proinflammatory factor from rat spleen lymphocytes.
• To investigate the chemical structure and inflammatory potential of the isolated factor.
• To differentiate the factor from known inflammatory mediators like oxidized glutathione and leukotriene C4.

Main Methods:

• Isolation using gel filtration and high voltage paper electrophoresis (HVE).
• Partial characterization including amino acid analysis and infrared spectroscopy.
• Assessment of proinflammatory activity using the carrageenin-induced rat paw edema model.

Main Results:

• A dialyzable, low molecular weight factor (X(2)) was isolated and shown to potentiate carrageenin-induced edema.
• Amino acid analysis revealed Glu, Cys, and Gly in a 1:1:1 ratio with gamma-glutamyl as the N-terminal residue.
• The factor exhibited similar HVE mobility to oxidized glutathione (GSSG) but lacked its activity; leukotriene C4 (LTC4) also showed no activity.
• Data suggest a structure with a gamma-glutamyl-cysteine-glycine (GSH) moiety conjugated to a hydroxylated unsaturated fatty acid, resulting in a net charge of -2 at pH 6.5 and Mr 600-650.

Conclusions:

• The isolated factor (X(2)) is a distinct proinflammatory mediator.
• It possesses a unique structure containing a GSH moiety linked to a fatty acid chain, differing from GSSG and LTC4.
• This factor represents a novel target for understanding and potentially modulating inflammatory processes.