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In situ hybridization of interferon-gamma producing peripheral blood mononuclear cells
I Rutenfranz1, A Kruse, H Kirchner
1Institute of Experimental Immunology, University of Marburg, Germany.
Abstract:
Individual interferon-gamma (IFN-gamma) producing cells in activated human peripheral blood mononuclear cells (PBMC) were characterized by in situ hybridization using [35S]-labelled antisense RNA probes. The proportion of positive cells expressing IFN-gamma mRNA varied according to the substances used for stimulation. IFN-gamma mRNA expressed a relatively low percentage of 1-8% PBMC after a single stimulus with mitogens or OKT-3 antibody and 20-30% of the cells were identified to synthesize IFN-gamma mRNA after stimulation with PHA + P-MA + OKT-3 antibody. The expression of IFN-gamma mRNA and production of the lymphokine was dependent on accessory cells. If accessory cells were replaced by recombinant interleukin-1 (IL-1) plus interleukin-6 (IL-6), then T-cell proliferation to phytohaemagglutinin (PHA) could be partially restored and measurable amounts of IFN-gamma were detected. The addition of interleukin-2 (IL-2) or phorbol-12-myristate-13-acetate to T cells stimulated with PHA, IL-1 and IL-6 did not restore the production of IFN-gamma to an extent comparable to that produced by T cells stimulated in the presence of accessory cells. In further studies, depletion of T-cell subsets showed that CD3+, CD4+, CD8+, CD29+ and CD45RA+ cells were involved in IFN-gamma production after mitogenic stimulation. In conclusion, our data demonstrate that IFN-gamma production is dependent on signals from accessory cells and IFN-gamma is synthesized by only a small proportion of T cells, that did not belong to a unique population, characterized by conventional cellular surface antigens.
Insights
Interferon-gamma (IFN-gamma) production in human cells depends on accessory cell signals. Only a small, diverse T-cell population synthesizes IFN-gamma, varying with stimulation methods.
Area of Science:
- Immunology
- Cell Biology
Background:
- Interferon-gamma (IFN-gamma) is a crucial cytokine in immune responses.
- Understanding the cellular sources and regulation of IFN-gamma production is vital for immunology research.
Purpose of the Study:
- To characterize individual IFN-gamma-producing cells in activated human peripheral blood mononuclear cells (PBMC).
- To investigate the role of accessory cells and specific T-cell subsets in IFN-gamma synthesis.
Main Methods:
- In situ hybridization using [35S]-labelled antisense RNA probes to detect IFN-gamma mRNA.
- Stimulation of PBMC with various mitogens, antibodies, and cytokines (IL-1, IL-6, IL-2).
- T-cell subset depletion (CD3+, CD4+, CD8+, CD29+, CD45RA+) to identify IFN-gamma producers.
Main Results:
- IFN-gamma mRNA expression varied significantly with stimulation (1-8% with single stimulus, 20-30% with combined PHA + P-MA + OKT-3).
- Accessory cells were essential for optimal IFN-gamma production; their absence could be partially compensated by IL-1 and IL-6.
- IFN-gamma production involved multiple T-cell subsets (CD3+, CD4+, CD8+, CD29+, CD45RA+), not a single defined population.
Conclusions:
- IFN-gamma production is critically dependent on accessory cell-derived signals.
- A limited proportion of T cells synthesize IFN-gamma, and these cells are phenotypically diverse.
- These findings provide insights into the regulation and cellular basis of IFN-gamma production in human immune responses.