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Distinct T-cell responses when BCG vaccination is delayed from birth to 6 weeks of age in Ugandan infants
F Lutwama1, B M Kagina, A Wajja
1South African Tuberculosis Vaccine Initiative, Institute of Infectious Diseases and Molecular Medicine.
Insights
BCG vaccination at birth in Uganda induces a stronger T-cell immune response compared to delayed vaccination at 6 weeks. This difference in immune response may impact tuberculosis protection.
Area of Science:
- Immunology
- Vaccinology
- Public Health
Background:
- BCG vaccine is crucial for tuberculosis prevention.
- In Uganda, timely BCG vaccination is often delayed for home-delivered infants.
- Understanding the impact of vaccination timing on immune response is critical.
Purpose of the Study:
- To investigate the effect of delayed BCG vaccination on infant immune responses.
- To compare T-cell induction between immediate and delayed BCG vaccination.
Main Methods:
- Assessed CD4(+) and CD8(+) T-cell responses using intracellular cytokine/cytotoxic marker assays.
- Utilized a 6-day proliferation assay to measure T-cell function.
- Enrolled 92 infants, comparing those vaccinated at birth versus 6 weeks.
Main Results:
- Infants vaccinated at birth showed greater induction of CD4(+) and CD8(+) T cells producing interferon-gamma (IFN-γ).
- Birth vaccination led to increased T-cell proliferation with enhanced production of IFN-γ, TNF-α, and IL-2.
- Delayed vaccination at 6 weeks resulted in a less robust T-cell response.
Conclusions:
- BCG vaccination timing significantly influences T-cell immune response patterns.
- The observed differences in T-cell induction may have implications for tuberculosis protection.
- Geographical and population factors may contribute to variations in BCG vaccine-induced immune responses.
Background:
In Uganda, the tuberculosis vaccine BCG is administered on the first day of life. Infants delivered at home receive BCG vaccine at their first healthcare facility visit at 6 weeks of age. Our aim was to determine the effect of this delay in BCG vaccination on the induced immune response.
Methods:
We assessed CD4(+) and CD8(+) T-cell responses with a 12-hour whole-blood intracellular cytokine/cytotoxic marker assay, and with a 6-day proliferation assay.
Results:
We enrolled 92 infants: 50 had received BCG vaccine at birth and 42 at 6 weeks of age. Birth vaccination was associated with (1) greater induction of CD4(+) and CD8(+) T cells expressing either interferon γ (IFN-γ) alone or IFN-γ together with perforin and (2) induction of proliferating cells that had greater capacity to produce IFN-γ, tumor necrosis factor α (TNF-α), and interleukin 2 together, compared with delayed vaccination.
Conclusions:
Distinct patterns of T-cell induction occurred when BCG vaccine was given at birth and at 6 weeks of age. We propose that this diversity might impact protection against tuberculosis. Our results differ from those of studies of delayed BCG vaccination in South Africa and the Gambia, suggesting that geographical and population heterogeneity may affect the BCG vaccine-induced T-cell response.
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