Cutting edge: NADPH oxidase modulates MHC class II antigen presentation by B cells.

Cutting edge: Conditional MHC class II expression reveals a limited role for B cell antigen presentation in primary and secondary CD4 T cell responses.

The activation, differentiation, and subsequent effector functions of CD4 T cells depend on interactions with a multitude of MHC class II (MHCII)-expressing APCs. To evaluate the individual contribution of various APCs to CD4 T cell function, we have designed a new murine tool for selective in vivo expression of MHCII in subsets of APCs. Conditional expression of MHCII in B cells was achieved u...

Secondary CD4 T Cell Responses Antigen Presentation in Primary and Expression Reveals a Limited Role for B Cell Cutting Edge: Conditional MHC Class II

Cutting edge: B cells promote CD8+ T cell activation in MRL-Fas(lpr) mice independently of MHC class I antigen presentation.

Spontaneous CD8+ T cell activation in MRL-Faslpr mice is B cell dependent. It is unclear whether this B-dependent activation is mediated by direct Ag presentation via MHC class I proteins (i.e., cross-presentation) or whether activation occurs by an indirect mechanism, e.g., via effects on CD4+ cells. To determine how CD8+ T cell activation is promoted by B cells, we created mixed bone marrow c...

A Role for NADPH Oxidase in Antigen Presentation

The nicotinamide adenine dinucleotide phosphate (NADPH) oxidase expressed in phagocytes is a multi-subunit enzyme complex that generates superoxide (O2 (.-)). This radical is an important precursor of hydrogen peroxide (H2O2) and other reactive oxygen species needed for microbicidal activity during innate immune responses. Inherited defects in NADPH oxidase give rise to chronic granulomatous di...

Cutting edge: limited specialization of dendritic cell subsets for MHC class II-associated presentation of viral particles.

Dendritic cells (DCs) are the most important APC. It was recently reported that there is a dichotomy for Ag presentation by DC subsets; exogenous Ags reach the MHC class I pathway, but not the MHC class II pathway, in CD8(+) DCs, whereas CD8(-) DCs only process Ags for the MHC class II pathway. In this study, we used virus-like particles (VLPs) to show that CD8(+) and CD8(-) DCs efficiently cap...