B cell antigen receptor specificity and surface density together determine B-1 versus B-2 cell development

Area of Science:

• Immunology
• Molecular Biology
• Developmental Biology

Background:

• Immunoglobulin (Ig) heavy (H) chain variable (V) region expression influences B cell lineage commitment.
• Specific V(H) transgenes (V(H)12) promote B-1 cell development, while others (V(H)B1-8, V(H)glD42) favor conventional B-2 cells.

Purpose of the Study:

• To investigate the developmental potential of B cells expressing two distinct B cell antigen receptors (BCRs).
• To determine how co-expression of BCRs favoring different B cell subsets impacts development.

Main Methods:

• Generation of double immunoglobulin heavy chain (IgH) insertion mice by crossing V(H)12 insertion mice with V(H)B1-8 or V(H)glD42 mice.
• Analysis of B cell populations and phenotypes in genetically engineered mouse models.
• Utilizing transgenic kappa chain to facilitate pairing with dual heavy chains.

Main Results:

• B cells coexpressing V(H)12 and either V(H)B1-8 or V(H)glD42 exhibit a B-2 cell phenotype.
• In mice coexpressing V(H)12 and V(H)B1-8 with a suitable kappa chain, both double-expressing B-2 cells and B-1 cells lacking V(H)B1-8 are generated.
• Single V(H)B1-8 producers are undetectable in these complex co-expression scenarios.

Conclusions:

• B-1 cell development appears to be selected by antigenic stimuli where BCR specificity and surface density are crucial.
• B-2 cell development may be less stringently regulated by these specific antigenic stimuli compared to B-1 cells.