Cd86 Conditional Knockout mouse models

Mouse Cd86 encodes B7-2, ortholog of human CD86, and is the costimulatory ligand dominating early T cell priming because it sits constitutively at low levels on resting antigen presenting cells and is rapidly upregulated after TLR or CD40 signaling, well before CD80 accumulates. Its IgV domain engages CD28 as a monomer with lower affinity but faster association than CD80, and it is likewise a preferred target for CTLA4 mediated transendocytosis, tying it directly to peripheral tolerance. CD86 also signals reciprocally into the presenting cell, influencing IL-6 production and immunoglobulin class switching in B cells. Because Cd80 provides substantial functional overlap, single nulls show only partial defects in germinal center formation and Th2 responses, and compound Cd80 Cd86 alleles are needed for clean loss of CD28 costimulation. Conditional flox designs with Cd19-Cre or Itgax-Cre localize the relevant presenter, while humanized knockins support CTLA4-Ig and anti-CD86 pharmacology.

A floxed Cd86 allele paired with Cre gives spatial control that whole body knockouts cannot offer. People use it to separate developmental roles from adult homeostasis, to model somatic mutations, and to match disease that begins in one organ.