The immunological effect of revaccination with Bacille Calmette-Guerin vaccine at 19 months of age

• Background: Bacille Calmette-Guerin (BCG) vaccination has important non-specific immune effects. In a randomized trial in Guinea-Bissau, BCG revaccination was associated with significantly increased survival in children who received diphtheria-tetanus-pertussis (DTP)-booster vaccine before enrolment and in children who did not receive micronutrient supplementation (MN). Within the trial we assessed the immunological effects of BCG revaccination. Methods: Children were randomized to BCG or nothing. Blood was sampled 6-11 weeks after randomization (early sample group) or 5-9 months later (late sample group). In vitro cytokine responses (interferon (IFN)-gamma, interleukin (IL)-13, tumor-necrosis-factor (TNF)-alpha, and IL-10) were assessed in whole blood cultures stimulated with lipopolysaccharide (LPS), purified protein derivative (PPD) or phytohaemagglutinin (PHA). Effect-modification by sex, DTP-booster vaccination and MN was studied. Results: Cytokines were measured in 345 infants. BCG was associated with significantly increased IFN-gamma (geometric mean ratio (GMR) = 4.54 (95% confidence interval: 3.13-6.58)) and IL-13 (GMR = 1.43 (1.00-2.05)) PPD responses, the effect being strongest in the early sample group. Across all three conditions BCG tended to increase IL-10 (LPS, PHA, PPD: GMR = 1.20, 1.12, 1.20), most pronounced in the late sample group. BCG reduced the TNF-alpha/IL-10 ratio in boys with DTP-booster at bleeding and increased it in those without (interaction test: p = 0.03). In children without MN, BCG was associated with reduced TNF-alpha response in the early sample group (p = 0.006), and increased IL-10 in the late sample group (p = 0.03). Conclusion: BCG revaccination resulted in a strong IFN-gamma response to PPD, which waned slightly over time. BCG also affected the pro-/anti-inflammatory balance, with reduced TNF-alpha and increased IL-10 responses to LPS, PHA and PPD. This effect depended on sex, DTP-booster vaccination and micronutrient supplementation, being most pronounced in children who had received DTP-booster before enrolment and children who had not received MN, i.e. the group of children which also had lower mortality after BCG revaccination. (C) 2013 Elsevier Ltd. All rights reserved.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Mikrobiologi inom det medicinska området (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Microbiology in the medical area (hsv//eng)

Nyckelord

BCG

Immunology

Non-specific effects

DTP-booster

Micronutrients

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