biostudies-literatureChaplin JWNIAID NIH HHSNIGMS NIH HHS4199-209https://www.ebi.ac.uk/biostudies/studies/S-EPMC3394853biostudies-literatureUnknown187(8)CD180 is homologous to TLR4 and regulates TLR4 signaling, yet its function is unclear. We report that injection of anti-CD180 mAb into mice induced rapid Ig production of all classes and subclasses, with the exception of IgA and IgG2b, with up to 50-fold increases in serum IgG1 and IgG3. IgG production after anti-CD180 injection was not due to reactivation of memory B cells and was retained in T cell-deficient (TCR knockout [KO]), CD40 KO, IL-4 KO, and MyD88 KO mice. Anti-CD180 rapidly increased both transitional and mature B cells, with especially robust increases in transitional B cell number, marginal zone B cell proliferation, and CD86, but not CD80, expression. In contrast, anti-CD40 induced primarily follicular B cell and myeloid expansion, with increases in expression of CD80 and CDJournal of immunology (Baltimore, Md. : 1950)Anti-CD180 (RP105) activates B cells to rapidly produce polyclonal Ig via a T cell and MyD88-independent pathway.PMC3394853R21 AI085311AI442572T32 GM007270AI52203R37 AI044257AI85311R01 AI052203T32 GM007270R01 AI044257Ledbetter JAKasahara SClark EAChaplin JWfalseAnti-CD180 (RP105) activates B cells to rapidly produce polyclonal Ig via a T cell and MyD88-independent pathway.CD180 is homologous to TLR4 and regulates TLR4 signaling, yet its function is unclear. We report that injection of anti-CD180 mAb into mice induced rapid Ig production of all classes and subclasses, with the exception of IgA and IgG2b, with up to 50-fold increases in serum IgG1 and IgG3. IgG production after anti-CD180 injection was not due to reactivation of memory B cells and was retained in T cell-deficient (TCR knockout [KO]), CD40 KO, IL-4 KO, and MyD88 KO mice. Anti-CD180 rapidly increased both transitional and mature B cells, with especially robust increases in transitional B cell number, marginal zone B cell proliferation, and CD86, but not CD80, expression. In contrast, anti-CD40 induced primarily follicular B cell and myeloid expansion, with increases in expression of CD80 and CD2011-01-01T00:00:00Z2011 Oct2025-04-18T16:16:09.606Z2019-03-27T00:55:30ZS-EPMC33948532191819710.4049/jimmunol.1100198