Detection and activation of HIV broadly neutralizing antibody precursor B cells using anti-idiotypes

Bancroft, Tara; DeBuysscher, Blair L.; Weidle, Connor; Schwartz, Allison; Wall, Abigail; Gray, Matthew D.; Feng, Junli; Steach, Holly R.; Fitzpatrick, Kristin S.; Gewe, Mesfin M.; Skog, Patrick D.; Doyle-Cooper, Colleen; Ota, Takayuki; Strong, Roland K.; Nemazee, David; Pancera, Marie; Stamatatos, Leonidas; McGuire, Andrew T.; Taylor, Justin J.

The BCR sequences from B cells binding to IB2 or IB3 were next compared with iglb12. On average, over 71% of the IB2binding B cells from all three individuals used the same V H gene as iglb12, V H 1-3 (Fig. 4 B) . In contrast, only 4.6% of individually sorted B cells expressed V H 1-3 when neither antiidiotype was used to select cells for sorting ( Fig. 4 B) , consistent with previous studies . In terms of the entire B cell repertoire, an average of 0.04% of the B cells bound IB2 and used V H 1-3 ( Fig. 4 C) . In contrast, only 11% of the IB3binding B cells used V H 1-3, which amounted to ∼0.001% of the B cell repertoire (Fig. 4 , B and C). Consistent with the crystal structure revealing that IB3 interacts with both the heavy and light chains of iglb12 (Fig. 2 , B and C), four out of the five IB3 + V H 1-3 + BCRs in which light chain sequences were recovered used the same light chain as igbl12, V K 3-20, or the closely related V K 3D-20 ( Fig. 4 D) . Surprisingly, IB2 + V H 1-3 + BCRs exhibited a slight preference for V K 3-20 ( Fig. 4 D) , which was not predicted by the heavy chain-only mode of binding indicated by the crystal structure (Fig. 2 , F-J).