Neutrophils Lend a Hand

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Science  27 Jan 2012:
Vol. 335, Issue 6067, pp. 381
DOI: 10.1126/science.335.6067.381-c
CREDIT: PUGA ET AL., NAT. IMMUNOL. 10.1038/NI.2194 (2011)

Diverse antibody production by B cells, which is critical for protection against a variety of infections, often requires the help of T cells. Marginal zone (MZ) B cells in the spleen, which are situated at the interface of the circulation and the immune system, are unusual in that they are able to provide a rapid, first line of antibody defense that is independent of T cells. Puga et al. now show that despite being independent of T cells, MZ B cells in humans do get help from another immune cell: neutrophils. These so-called “B cell-helper neutrophils” were located in close proximity to MZ B cells in the spleens of humans, non-human primates, and mice. Their localization to the spleen coincided with postnatal colonization by microbes. Through the production of the cytokines APRIL, BAFF, and interleukin-21, B cell–helper neutrophils promoted the expression of activation-induced cytidine deaminase (AID), antibody isotype class switching, and somatic hypermutation by MZ B cells, events that help to diversify the antibody response but are typically associated with T cell help. Reduced MZ B cell numbers and altered MZ B cell antibody responses in patients deficient in neutrophils revealed the importance of B cell–helper neutrophils in vivo.

Nat. Immunol. 10.1038/ni.2194 (2011).

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