Deduced amino acid sequences of the VH genes utilized by the mAbs produced by B-1a, B-1b, and B-2 cells. In each cluster, the top sequence is given for comparison and represents the reported germ-line VH gene displaying the highest degree of identity to the expressed VH genes. The V3-23, V3-30, V3-33, H11, and V3-9 genes are members of the VH3 gene family. The V4-34, V4-39, VIV-4, V4-31, V4-4, V4-28, and V4-59 genes are members of the VH4 gene family. The V1-2, V1-46, V1-69, and DP-3 genes are members of the VH1 gene family. Dashes indicate identities. Solid lines on the top of each sequence depict CDR. These sequence data are available from EMBL/GenBank/DDBJ under the accession numbers listed in Table I.