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In vitro activation of human T lymphocytes by Haemophilus influenzae type b capsular polysaccharides
C C Peeters1, A M Tenbergen-Meekes, C J Heijnen
1Department of Immunology, University Hospital for Children and Youth, Het Wilhelmina Kinderziekenhuis, Utrecht, The Netherlands.
Abstract:
Polyribosilribitolphosphate (PRP), the capsular polysaccharide from Haemophilus influenzae type b, is a T-cell-independent type 2 antigen. In vitro culture of adult peripheral blood T cells with 15 micrograms/ml PRP leads to induction of interleukin-2 receptor (IL-2R) expression on up to 10% of T cells. These cells are CD4+ and carry the alpha beta T-cell receptor. PRP, at concentrations above 1-5 micrograms/ml, can also induce in vitro proliferation of both adult and neonatal T cells. We conclude that PRP acts as a human T-cell mitogen. The in vitro proliferative response as well as IL-2R expression was studied in T cells derived from adults after vaccination with native PRP, with PRP conjugated to a carrier protein, or with diphtheria toxoid. Vaccination with conjugated PRP decreased the doses of PRP required for in vitro induction of IL-2R expression and T-cell proliferation. This indicates that vaccination with PRP conjugated to a carrier protein improves the in vitro T-cell response to PRP activation.
Insights
Polyribosilribitolphosphate (PRP) from Haemophilus influenzae type b acts as a T-cell mitogen, inducing proliferation and interleukin-2 receptor expression. Vaccination with conjugated PRP enhances this in vitro T-cell response.
Area of Science:
- Immunology
- Microbial Pathogenesis
Background:
- Polyribosilribitolphosphate (PRP) is the capsular polysaccharide of Haemophilus influenzae type b.
- PRP functions as a T-cell-independent type 2 antigen.
Purpose of the Study:
- To investigate the mitogenic properties of PRP on human T cells.
- To evaluate the impact of vaccination on T-cell responses to PRP.
Main Methods:
- In vitro culture of adult peripheral blood T cells with PRP.
- Assessing interleukin-2 receptor (IL-2R) expression and T-cell proliferation.
- Analyzing T cells from adults vaccinated with native PRP, conjugated PRP, or diphtheria toxoid.
Main Results:
- PRP induces IL-2R expression on CD4+ T cells and promotes T-cell proliferation in vitro.
- PRP acts as a human T-cell mitogen at concentrations above 1-5 micrograms/ml.
- Vaccination with conjugated PRP lowers the required PRP doses for T-cell activation and proliferation.
Conclusions:
- PRP exhibits mitogenic activity on human T cells.
- Conjugated PRP vaccination improves the in vitro T-cell responsiveness to PRP activation.