Two distinct paraproteins (IgG(2)-K and IgM-K) from one patient shared identical light chains and significant portions of the variable regions of the heavy chains. Idiotypic determinants on the IgG and IgM molecules were shared. Earlier studies, using class-specific antisera, showed that these paraproteins were produced by two different populations of cells. The present study, using rhodamine and fluorescein conjugates of the anti-idiotype antisera, demonstrates that all plasma cells that contain immunoglobulin, whether IgG or IgM, stained with anti-idiotype antisera; this occurred irrespective of whether the antisera were made originally against the patient's IgG or IgM. This, plus previous data, indicates that both populations of cells share genetic information for the constant and variable regions of light chains and significant portions of the heavy-chain genes. These, and other cited data, strongly suggest the occurrence of a switch-over from IgM to IgG synthesis in the same cell during the course of the normal immune response.

Animals↗

PubMed1971

N-terminal amino-acid sequence of African lungfish immunoglobulin light chains.

The sequence of the N-terminal ten amino acids of the unblocked light chains derived from the low molecular weight immunoglobulin of a dipnoid fish, the African lungfish (Protopterus aethiopicus), has been determined. A degree of sequence heterogeneity as extensive as that displayed by pooled mammalian light chains was encountered. The major N-terminal sequence of the amino acids of light chains from lungfish immunoglobins can be made homologous with that of various Elasmobranchean, Chondrostean, Avian, and Mammalian species if an internal deletion of two base triplets in the gene coding for light chains from lungfish immunoglobulins is assumed. The existence of a deletion and/or insertion mechanism may have profound biological significance, since it would be ideal for the introduction of variability into immunoglobulin chains without sacrificing certain integral features of the antibody molecule.

Amino Acid Sequence↗

PubMed1971

Anti-antibody activity of a monoclonal macroglobulin.

A monoclonal macroglobulin from a patient with Waldenström macroglobulinemia has been shown to have antiglobulin activity of a new type, namely, that of a true anti-antibody. The protein reacts with human, primate, and rabbit IgM and IgG, only when the target immunoglobulin is complexed to an antigen. The implications of the general findings of antiglobulin activity of monoclonal proteins is discussed in relation to the possible etiology of the disease.

Animals↗

PubMed1971

Heavy-chain variable regions in normal and pathological immunolobulins.

Aminoacid sequence analysis of immunoglobulin G heavy chains from each of 15 normal individuals showed the presence of VHIII subgroup sequences in all individuals, to an extent of about 15-25% of the total. Therefore, different subgroups of the heavy-chain variable region are not products of alleles of a single gene.N-terminal aminoacid sequences were determined for ten heavy chains of myeloma proteins that belonged to the VHIII subgroup. Our results demonstrate the existence of a "hypervariable" region of sequence between positions 30 and 35, homologous to one of the three hypervariable regions of light chains. At several positions, variants of the basic sequence are repeated in different proteins. It is likely that such variants are derived from several recently evolved genes that constitute the VHIII subgroup.

Amino Acid Sequence↗

PubMed1971