An anti-lipid A antibody obtained from the human fetal repertoire is encoded by VH6-V lambda 1 genes.

The human hybridoma cell line CB-201 has been obtained from a fusion of fetal spleen lymphocytes (31st gestational week) with heteromyeloma cells. The IgM (lambda) secreted was found to bind to lipid A, whereas other endogenous and exogenous antigens were not recognized. The CB-201 antibody is encoded by the unmutated VH6 gene recombined with DN4 and JH3 elements and a V lambda subgroup 1 gene. Therefore, a VH gene, which was previously described to be over-represented in the fetal repertoire and to be expressed in autoantibody-producing B cells, may encode an anti-bacterial specificity.