The Jκ use in splenic wt and CD19^-/- B cells. The Jκ use in purified splenic B cells from wt and CD19^-/- mice was determined as described in “Materials and methods.” Analysis was performed for 3 wt and 3 CD19^-/- mice, and for each mouse 30 to 50 sequences bearing in-frame Vκ-Jκ rearrangements were considered. Results for individual mice are shown. Percentages of rearrangements using Jκ1/2 (□) or Jκ4/5 (▦) for individual mice are presented. For each group, a broken line represents the mean Jκ1/2 and Jκ4/5 use. Asterisk indicates values that are statistically different (P < .05).