THE VKIIIB LIGHT CHAIN SUB-SUBGROUP - RESTRICTED ASSOCIATION WITH MU-HEAVY CHAIN IN NORMAL HUMAN-SERUM

Abstract

The VKIII human .kappa. L-chain subgroup has been serologically and structurally divided into 2 sub-subgroups, VKIIIa and VKIIIb. VKIIIb has been shown previously to be strikingly prevalent in IgM autoantibodies, but no studies have been performed to determine H-chain isotype association with VKIIIb L-chain in normal human serum. The VKIIIb sub-subgroup was shown here to be associated with .mu. H-chain in normal human serum, but was not detected in association with .gamma. or .alpha. H-chain. Approximately 25 .+-. 15% of IgM-.kappa. was determined to be VKIIIb. Both intact IgG and purified L-chains from pooled IgG did not bind monoclonal anti-VKIIIb, indicating that the determinants recognized by anti-VKIIIb are not merely masked in intact IgG. These results are the 1st report of a L-chain sub-subgroup showing preferential association with a H-chain isotype.