Chemical Typing of Human Immunoglobulin Vκ Subgroups

Abstract

WITHIN each of the three types of immunoglobulin chains, κ, λ and H, subgroups of variability have been defined on the basis of characteristic basic sequences. In human immunoglobulins, three subgroups have been described for the κ chains¹, five for the λ chains² and three for the H chains^{3, 4}, one of the latter being closely homologous to that of a mouse VH region⁵. Antigenic determinants, specific for each of the Vκ subgroups⁶ and at least for some of the Vλ^{7, 8}, have made possible attempts to type subgroups serologically. The production of specific antisera is, however, a difficulty and this led Frangione et al., who were concerned with the typing of classes and subclasses of immunoglobulins, to propose a chemical way of typing for the discrete isotypes based on sequence differences around the cysteine residues of the chains⁹. By looking at the published sequences of human Vκ regions¹⁰ it can be seen that some peptides around cysteines 1 (position 23) and 2 (position 88) are characteristic of each Vκ subgroup. (The nomenclature of κ subgroups used here is taken from ref. 10 and so, differs from that used in refs 1 and 6.)