Distinct TLR-mediated cytokine production and immunoglobulin secretion in human newborn naive B cells

MA Pettengill, SD van Haren, N Li… - Innate …, 2016 - journals.sagepub.com
MA Pettengill, SD van Haren, N Li, DJ Dowling, I Bergelson, J Jans, G Ferwerda, O Levy
Innate immunity, 2016journals.sagepub.com
Neonatal innate immunity is distinct from that of adults, which may contribute to increased
susceptibility to infection and limit vaccine responses. B cells play critical roles in protection
from infection and detect PAMPs via TLRs, that, when co-activated with CD40, can drive B-
cell proliferation and Ab production. We characterized the expression of TLRs in circulating
B cells from newborns and adults, and evaluated TLR-and CD40-mediated naïve B-cell
class-switch recombination (CSR) and cytokine production. Gene expression levels of most …
Neonatal innate immunity is distinct from that of adults, which may contribute to increased susceptibility to infection and limit vaccine responses. B cells play critical roles in protection from infection and detect PAMPs via TLRs, that, when co-activated with CD40, can drive B-cell proliferation and Ab production. We characterized the expression of TLRs in circulating B cells from newborns and adults, and evaluated TLR- and CD40-mediated naïve B-cell class-switch recombination (CSR) and cytokine production. Gene expression levels of most TLRs was similar between newborn and adult B cells, except that newborn naïve B cells expressed more TLR9 than adult naïve B cells. Neonatal naïve B cells demonstrated impaired TLR2- and TLR7- but enhanced TLR9-mediated cytokine production. Significantly fewer newborn naïve B cells underwent CSR to produce IgG, an impairment also noted with IL-21 stimulation. Additionally, co-stimulation via CD40 and TLRs induced greater cytokine production in adult B cells. Thus, while newborn naïve B cells demonstrate adult-level expression of TLRs and CD40, the responses to stimulation of these receptors are distinct. Relatively high expression of TLR9 and impaired CD40-mediated Ig secretion contributes to distinct innate and adaptive immunity of human newborns and may inform novel approaches to early-life immunization.
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