Molecular cloning of HA + B lymphocytes. PBMCs from 4 anonymous blood bank donors were stained as in Figure 4B . Single H1 + , H3 + , or H1 neg H3 neg CD20 + B-cells were sorted to perform molecular cloning and analysis of their paired V H V L Ig regions as described in Material and Methods section. A–E. Distribution of V H (A), D H (B), J H (C), V k (D) and J k (E) gene use across arrays of B-cells sorted from each donor (16 and 18 HA + clones from donors #1 and #2; 35 HA + and 20 HA neg clones from donor 3; 16 HA + and 16 HA neg clones from donor #4. F–I. Number of mutations in H1 + and H1 neg CD20 + B-cells from donors #3 and #4, which cause dissimilar (F, H) or similar (G, I) amino acid substitutions in V H (G,I) and V L (F,H). NS and ** indicate not significant, or significant (p