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Lymphotoxin produced by human B- and T-cell lines appears in two distinct forms
M Lantz1, L Lindvall, P Pantazis
1Department of Medicine, University of Lund, Sweden.
Molecular Immunology
|January 1, 1991
Summary
This study investigated lymphotoxin (LT) production and release in human B- and T-cells. Researchers identified two distinct molecular weight forms of LT with complex N-linked oligosaccharides.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Lymphotoxin (LT) is a cytokine involved in immune regulation.
- Understanding LT production and release mechanisms is crucial for immunology research.
Purpose of the Study:
- To investigate the molecular characteristics and release mechanisms of lymphotoxin (LT) in human B- and T-cell lines.
- To determine the glycosylation status and subcellular localization of intracellular LT.
Main Methods:
- Metabolic labeling of B- and T-cell lines with 14C-leucine and 35S-methionine.
- Immunoprecipitation of LT, followed by SDS-PAGE and fluorography.
- Deglycosylation using N-glycanase and endoglycosidase H (endo H).
- Subcellular fractionation using Percoll density gradients.
Main Results:
- Two distinct molecular weight forms of LT were identified in both cell supernatants and extracts.
- Monensin inhibited LT release, suggesting a role for vesicular transport.
- Deglycosylation studies confirmed the presence of two LT forms and revealed complex-type N-linked oligosaccharides.
- Intracellular LT was localized to intermediate density fractions, excluding lysosomes.
Conclusions:
- Human B- and T-cells produce and release LT in two distinct molecular weight forms.
- These LT forms contain complex-type N-linked oligosaccharides.
- LT release is an active process sensitive to ionophore treatment, and intracellular LT is not lysosomally localized.