Association of variable and constant regions of immunoglobulin heavy chains

Antigenic determinants of heavy chain variable regions: immumological typing of the human immunoglobulin VHIII subgroup

An antigenic determinant of the VHIII variable region subgroup was defined by means of a heterologous specific antiserum using a hemagglutination inhibition procedure. The specificity of this antiserum was established in inhibition experiments with proteins either of known primary structure or belonging to a definite VH subgroup. A series of IgG, IgA, IgM and IgD monoclonal proteins was examined for the presence of this VHIII subgroup antigenic determinant. The data showed that 50% of the IgG, 62% of the IgA, 55% of the IgM and 41% of the IgD were VHIII-positive, and that certain "blocked" monoclonal immunoglobulins belonged to this subgroup. A preferential association of the VHIII antigenic determinant with the IgG1 and IgG3 subclasses was observed among IgG myeloma proteins while the preferential association was only observed with the IgG1 subclass when anti-Rh antibodies were studied. The VHIII subgroup exhibited nonallelic behavior.

Chemical and genetic characterization of a monoclonal IgA(lambda) protein with both cryo- and pyro-precipitability

Studies of a monoclonal IgA (lambda) protein with both cryo- and pyro-precipitability show that it belongs to the IgA2 subclass and is positive for the A2m(2) allotypic marker. Like other cryoglobulins, this protein also has an unblocked light chain, and its heavy chain belongs to the VHI subgroup. The first 22 N-terminal amino acids of the lambda chain of this protein showed less than 65% homology with those of other human lambda chains but showed 86% identity with that of an amyloid fibril protein reported by others. The alpha chain of this protein appears to have more glutamic acid or glutamine, or both, and less isoleucine residues than other human alpha chains.