AI Article Synopsis
- A BCG vaccine trial conducted in northern Malawi from 1986-1989 studied the delayed-type hypersensitivity (DTH) response of 2418 participants over 1-36 months after vaccination, noting variations based on age, sex, and previous DTH status.
- The DTH response peaked at 31-90 days post-vaccination but showed significant decline by 181-365 days, especially in individuals under 15 years old at the time of vaccination.
- The study suggests that environmental factors (like high exposure to other infections) might contribute to a quicker decline in DTH responsiveness in tropical regions compared to temperate ones, and that genetics or past exposure history could affect individuals' ability to sustain these immune responses.
Article Abstract
During 1986-1989, a bacille Calmette-Guérin (BCG) vaccine trial was carried out in northern Malawi. The effects of age, sex, and prevaccination delayed-type hypersensitivity (DTH) on the time course of the DTH response over 1-36 months after vaccination were studied in 2418 persons. DTH response increased rapidly, to peak at 31-90 days after vaccination, when most persons had a measurable response. This was followed by a marked decline by 181-365 days, particularly in those <15 years old at vaccination, followed by a more gradual decline. Prevaccination DTH was the single best predictor of postvaccination DTH. BCG-induced DTH responsiveness appears to decline more rapidly in tropical than in temperate environments. This may reflect high prevalence of exposure to other infections, which induce a Th2 bias or compete for "space" within the T lymphocyte compartment. The inability of some persons to mount a persistent DTH response probably reflects genetic background and/or environmental exposure history.
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| http://dx.doi.org/10.1086/342416 | DOI Listing |
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