151. Estimating point and interval frequency of antigen-specific CD4+ T cells based on short in vitro expansion and improved poisson distribution analysis.
- Author
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Di Lullo G, Ieva F, Longhi R, Paganoni AM, and Protti MP
- Subjects
- CD4 Lymphocyte Count, Cell Proliferation, Cells, Cultured, Epstein-Barr Virus Nuclear Antigens immunology, Humans, Immunologic Memory immunology, Interferon-gamma metabolism, Interleukin-5 biosynthesis, Lymphocyte Activation immunology, Poisson Distribution, Reproducibility of Results, CD4-Positive T-Lymphocytes cytology, CD4-Positive T-Lymphocytes immunology, Epitopes immunology
- Abstract
Background: Knowledge of antigen-specific CD4(+) T cells frequencies is pivotal to the choice of the antigen to be used in anti-viral and anti-tumor vaccination procedures and for monitoring of immune responses. Methods that employ small cell numbers from patient samples, are easy to perform and do not require complex techniques/instrumentations and therefore standardization are desirable., Methodology/principal Findings: Purified blood CD4(+) T cells from healthy donors were cultured with autologous antigen presenting cells in several replicate wells in equal numbers in the absence (un-stimulated wells) or in the presence of synthetic peptides corresponding to viral antigens promiscuous HLA-DR epitopes (antigen-stimulated wells). At day 7 of culture low dose IL-2 was added and at day 14 IFN-γ and IL-5 release in the supernatant was measured. A statistical analysis approach, based on Poisson distribution, was then implemented to calculate the frequency of viral-specific CD4(+) T cells. We first determined a patient-specific exceptionality threshold of cytokine release in the un-stimulated wells and then, based on this threshold, we counted the inactive/active wells within the antigen-stimulated wells. This number, along with the number of cells per well, allowed the point and interval estimates of frequencies. A ready-to-use Excel worksheet template with automatic calculations for frequencies estimate was developed and is provided as a supplemental file (Table S9)., Conclusions/significance: We report a simple experimental procedure combining short term in vitro cell culture with statistical analysis to calculate the frequency of antigen-specific CD4(+) T cells. The detailed experimental procedure along with the Excel applicative are a valuable tool for monitoring immune responses in the clinical practice.
- Published
- 2012
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