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Updated: May 7, 2026
An In vitro Model to Study Immune Responses of Human Peripheral Blood Mononuclear Cells to Human Respiratory Syncytial Virus Infection
Published on: December 11, 2013
Identification of a histamine release inhibitory factor produced by human mononuclear cells in vitro
R Alam1, J A Grant, M A Lett-Brown
1Department of Internal Medicine, University of Texas Medical Branch, Galveston 77550.
Abstract:
Human mononuclear cells (MNC) secrete histamine-releasing factor(s) (HRF) when cultured in vitro. HRF induces the release of histamine and other mediators from basophils and mast cells. We have shown that MNC also produced a histamine release inhibitory factor (HRIF), and that the synthesis is augmented by culture with physiologic concentrations of histamine (10(-10) to 10(-6) M) and by the mitogen concanavalin A (Con A). HRIF does not affect release initiated by other secretagogues such as allergen, anti-IgE, C5a, Con A, and phorbol myristate acetate. HRIF requires a preincubation with the cells for 5-10 min for maximal inhibition, and this effect is not abolished by washing the cells after the preincubation. The biological activity of HRIF is protease-sensitive, neuraminidase-resistant, and relatively heat-stable. HRIF can be distinguished from HRF by a lower apparent molecular mass (8,000-10,000 D).
Insights
Human mononuclear cells (MNC) produce a histamine release inhibitory factor (HRIF) that regulates histamine release from immune cells. HRIF synthesis is enhanced by histamine and Con A, offering a novel regulatory mechanism.
Area of Science:
- Immunology
- Cell Biology
Background:
- Human mononuclear cells (MNC) secrete histamine-releasing factors (HRF).
- HRF stimulates histamine and mediator release from basophils and mast cells.
Purpose of the Study:
- To investigate the production and characteristics of a histamine release inhibitory factor (HRIF) by MNC.
- To differentiate HRIF from HRF.
Main Methods:
- In vitro culture of human MNC.
- Assay of HRIF activity and characterization of its properties (protease sensitivity, heat stability, molecular mass).
Main Results:
- MNC produce HRIF, which inhibits histamine release.
- HRIF synthesis is augmented by histamine and concanavalin A (Con A).
- HRIF has distinct properties from HRF, including lower molecular mass (8-10 kDa).
Conclusions:
- MNC synthesize an endogenous HRIF that modulates histamine release.
- HRIF represents a distinct factor from HRF with a regulatory role in immune responses.
