A directory of human germ-line V kappa segments reveals a strong bias in their usage.

From the genomic DNA of a single individual, we have amplified, cloned and sequenced 37 human germ-line V kappa segments. Four of these segments were new. We then compiled a comprehensive directory of all germ-line V kappa segments and identified 50 different sequences with open reading frames. Comparison with 236 rearranged sequences revealed that no more than 24 of these germ-line sequences could be assigned rearranged counterparts, that some of these were rarely used, and that only about 11 sequences are used frequently. This suggests that the expressed V kappa repertoire is mainly derived from a limited number of segments. Most surprisingly, the J kappa-distal region of the locus appears to be rarely used: we could unambiguously assign 162 rearranged sequences to V kappa segments of the J kappa-proximal region, but only 5 to segments of the J kappa-distal region.