GENE EXPANSION AND ANTIBODY VARIABILITY

The reconstruction of a fragment of primordial genetic information from modern proteins: PGI-FI (AHAP)

In a continuation of earlier studies the connection between a reconstructed ancestral histone IV peptide and various sequences from non-histone proteins was investigated. This peptide, AHAP, was found to be related to partial peptides from the human encephalitogenic protein, immunoglobulin L-chains, fibrinopeptide A, glyceraldehyde-3-phosphate-dehydrogenase, TMV coat protein and several other proteins and protein families; for comparison, nodal sequences were employed wherever possible. The widespread occurrence of genetic information expressed in AHAP caused us to rename the peptide PGI-FI (primordial genetic information-fragment 1) since this peptide is apparently part of a very primitive and ancient genetic information, and may be called "protogene".

Isolation of IgA1 from human serum by affinity chromatography using an immobilized extract of the albumin gland of Helix pomatia

An extract of the albumin gland of Helix pomatia was linked to Sepharose-4B and used to prepare IgA from group O human serum; immunoelectrophoresis showed that the preparation was free of IgG and IgM. From studies with specific IgA subclass antisera and by comparison with the activity of jacalin-produced material the Helix pomatia extract was found to be IgA1 specific. The preparation had red cell anti-A, B specificity and was suitable for standardizing and controlling anti-human IgA reagents. Preparations using six different carbohydrates as eluants inhibited the agglutination reaction between anti-human IgA and IgA-coated red cells to varying degrees. The pattern of reactions suggested that N-acetyl glucosamine was the IgA binding site for Helix pomatia; this differed from its blood group A determinant (N-acetyl galactosamine) which was the same as that for the IgA1 reactive component of jacalin.

Definition of the human immunoglobulin variable lambda (IGLV) gene subgroups

Comparison of 60 human immunoglobulin variable lambda (IGLV) sequences allowed us to define seven subgroups designated V lambda I to V lambda VII. We demonstrate that all lambda proteins sequenced so far fall into the subgroups I, II, III and VI, and that the lambda regions previously assigned to subgroups IV and V belong, in fact, to subgroups III and II, respectively. Four sequences not belonging to any of the subgroups I, II, III and VI define the new subgroups IV, V and VII. Interestingly, these subgroups show a higher homology to rabbit or mouse V lambda genes than to the other human V lambda subgroups. By comparison of the proteins either with the sequences deduced from the germ-line genes or with the consensus sequences, the rate of amino acid changes due to somatic mutations or allelic variations was evaluated in several lambda proteins. Framework and complementarity-determining regions of the human IGLV genes and proteins were delineated. Alignment of the lambda sequences shows that functional V-J rearrangement occurs, with or without deletion of nucleotides encoding one or two amino acids at the 3' end of the V gene. Diversity of the third complementarity-determining region is due to somatic mutations and to flexible V-J junction, but there is no evidence of N-diversity in the human lambda locus.

Rapid molecular weight estimation and separation of selected immunoglobulin chains by high speed gel filtration

Rapid and reliable molecular weight estimations of reduced and alkylated immunoglobulin heavy or light chains were performed by high speed gel filtration in 6 M guanidinium chloride using a short (30 cm X 7.5 mm) TSK 3000 SW type column. Molecular weight estimations based on Kav values of eluted polypeptides and glycopolypeptides were generally unaffected by protein bound carbohydrate. Rapid separation of immunoglobulin H and L chains was also achieved during high speed gel filtration.

Successful therapy of crystalcryoglobulinemia: a case report

Successful therapy for a case of multiple myeloma with a spontaneously crystallizing cryoglobulin of the IgG2-kappa light chain variety was achieved, using both continuous-flow cell centrifugation plasmapheresis to rapidly lower the M component and combination chemotherapy with phenylalanine mustard, prednisone, procarbazine, and vincristine to control the myeloma process. This resulted in resolution of incapacitating large and small necrotic cutaneous ulcerations of the extremities. Physicochemical studies of the crystalcryoprotein demonstrated that cryoprecipitation was rapid and accompanied by the formation of needle-shaped crystals, yet was completely reversible at 37 degrees C. Cryocrit determinations varied depending upon relative centrifugal forces and temperature and did not always relate linearly to the amount of abnormal protein, thus making these alone unreliable in assessing response to therapy.

Monoclonal IgM cryoglobulinemia associated with gamma-3 heavy chain disease: immunochemical and biochemical studies

A patient (Mia) with a monoclonal IgM(kappa) cryoglobulin (cryo IgM) developed additional heavy chain disease proteins of the gamma3 subclass 8 years later. Biochemical studies of the cryo IgM indicated that the heavy chain was VHI, but the NH2-terminal amino acid sequence of the light chain did not permit a definite assignment of its Vkappa subgroup. Two major fragments of the gamma3 chain were distinguishable by electrophoresis in sodium dodecyl sulfate polyacrylamide gel. The smaller component (designated Mia F) had a molecular weight of approximately 30 000 and the larger component (designated Mia S) 35 000. Both fragments had G3m(21) and G3m(27) allotypic determinants. These data and the NH2-terminal amino acid sequence of the gamma chain fragments suggested that Mia S consists of the major part of the gamma3 hinge region plus the CH2 and CH3 domains of the gamma3 chain, whereas Mia F may be derived from the former as a result of postsynthetic cleavage. The partial amino acid sequence of the Mia S fragment is homologous to the hinge region amino acid sequence of human gamma3 chains reported in the literature, with only one amino acid difference out of the 11 residues compared. This difference may represent an allotypic difference within the gamma3 subclass. Alternatively, the production of Mia S may have resulted from the accidental derepression of a "silent" constant region gene not expressed in normal individuals.

Evidence for quasi-silent germline genes coding for phylogenetically ancient determinants of the rabbit a locus allotypes

Anti-a2 sera raised in a3 rabbits are shown to detect determinants on a2 molecules which are different from those detected by anti-a2 sera raised in a1 animals. The former determinants are occasionally observed at a low level in rabbits of the a1 allotype and at a high level in sera of Leporidae of different genera. The two types of anti-a2 sera are shown to compete for the same sterical region of the a2 molecules. All homogeneous a2 molecules which have been tested show both types of determinants.

Partial amino acid sequences of kappa-chains of rat immunoglobulins: genetic and evolutionary implications

Partial amino acid sequences have been determined for several kappa-type light chains prepared from sera or urine of inbred LOU/C/Wsl rats bearing plasma cell tumors. Comparison of these sequences with those of human, rabbit, and mouse kappa-chains available in the literature indicates that the constant region of rat kappa-chains shows more amino acid sequence homology to that of the mouse kappa-chain than to human and rabbit kappa-chains, a result expected from the phylogenetic relationship of the species compared. Examination of the N-terminal amino acid sequences indicated that the variable regions of rat kappa-chains can also be classified into subgroups according to degree of sequence homology in a manner similar to that done for kappa-chains of other species (e.g., human, rabbit, and mouse). However, the prototype amino acid sequences of kappa-chain variable region subgroups of the rat were not homologous to those of other species including the closely related mouse. The implications of this observation with respect to the genetics and evolution of immunoglobulins are discussed.