Three-dimensional landscapes of IGHV gene usage in conjunction with IGHJ usage show variation between antigen-inexperienced and memory B-cell populations. Landscapes illustrate the pairing of individual IGHV and IGHJ gene combinations in the Ig gene sequences, as identified by V-Quest. The relative frequency (y-axis) of individual IGHV genes (x-axis) using IGHJ genes (z-axis) in (A) Transitional (IgD⁺CD27⁻CD10⁺, n = 433), (B) Naive (IgD⁺CD27⁻CD10⁻, n = 662), (C) Switched memory (IgD⁻ and either IgG⁺ or IgA⁺, n = 1293), and (D) IgM memory (IgD⁺CD27⁺, n = 1209) populations is shown. Allelic variations of each IGHV gene are not shown. P values for χ² comparisons of individual IGHV gene usage between the different groups are indicated in Table 2.