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Cytokines produced in lymph follicles
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This study investigated cytokine production in human lymph follicles. Follicular dendritic cells enhanced the production of interleukin-6 (IL-6) and tumor necrosis factor (TNF) in germinal center reactions.
Area of Science:
- Immunology
- Cell Biology
Background:
- Germinal center reactions within lymph follicles are crucial for adaptive immunity but remain incompletely understood.
- The specific roles of different cell types, including B cells, T cells, macrophages, and follicular dendritic cells, in cytokine production during these reactions require further elucidation.
Purpose of the Study:
- To investigate cytokine production by human lymph follicle cells in vitro.
- To determine the influence of macrophages and follicular dendritic cells on cytokine secretion during germinal center reactions.
Main Methods:
- Human tonsillar lymph follicle cells, including B and T lymphocytes, were isolated.
- Cell populations were either enriched or not enriched with macrophages or follicular dendritic cells.
- Cytokine production was assessed in vitro following stimulation with phytohemagglutinin or pokeweed mitogen.
Main Results:
- Interleukin-6 (IL-6) and tumor necrosis factor (TNF) were detected in culture supernatants upon stimulation.
- Interleukin-1 beta (IL-1 beta) secretion was variable and dependent on tissue origin, stimulation, and cell composition.
- Follicular dendritic cell-containing populations exhibited higher IL-6 and TNF production compared to B and T cell-only cultures.
Conclusions:
- Cytokine production, particularly IL-6 and TNF, is influenced by the cellular composition of lymph follicles.
- Follicular dendritic cells play a significant role in enhancing IL-6 and TNF secretion within the germinal center microenvironment.
Abstract:
The events occurring inside lymph follicles during a germinal center reaction are poorly understood. Using B and T lymphoid cell populations prepared from human tonsillar lymph follicles, and enriched or not in macrophages or in follicular dendritic cells, we examined the production of cytokines by these cells in vitro. Interleukin 6 (IL-6) and tumor necrosis factor (TNF) were found in the supernatants of cultures stimulated with phytohemagglutinin or pokeweed mitogen. IL-1 beta was occasionally detected; its secretion apparently depends on the origin of the tonsils, the stimulation, and the cell populations. IFN-gamma and IL-2 were not produced in significant amounts by these lymph follicle cells. IL-4 was only found in very low concentrations in the supernatant of the different cell cultures. The cell populations containing follicular dendritic cells produced more IL-6 and TNF than the others, especially than those composed of only B and T cells.