A new extra sequence at the amino terminal of a mu heavy chain disease protein (DAG).

The primary structure of a human mu heavy chain (DAG) protein is described. The native protein is a circular decamer with a molecular weight (Mr) of 500 kDa, each decamer being constituted of the constant domains C mu 2, C mu 3 and C mu4 and interlinked by 15 disulfide bridges. At its NH2-terminal each monomeric chain starts with an "extra sequence". The amino acid sequence of this segment is Arg-Gln-Ser-Asp-Asp-Pro-Val-Leu-Arg-Gly-Thr-Thr-Val-Pro-Val-Thr-Glu and its reinitiation point is located at Val223 (Gal numbering), at the beginning of C mu 2. This sequence has no homology with any other protein included in the present databases.

Characterization of jacalin, the human IgA and IgD binding lectin from jackfruit.

The lectin jacalin from the jackfruit Artocarpus heterophyllus reacts by precipitation and western blotting with human IgA1 and IgD but not with IgA2 (nor IgG and IgM). However, it weakly binds IgA2 as shown by affinity chromatography and competitive ELISA. Predominantly reactive carbohydrates are D-galactose and N-acetyl D-galactosamine. Jacalin has an apparent Mr of about 54,000 and is probably made up of three non-glycosylated and one glycosylated non-covalently linked subunits. Its electrophoretic properties and amino acid and carbohydrate composition are indicated.

The amino acid sequence of a lambda light chain presenting abnormal physicochemical and antigenic features.

The amino acid sequence of the light chain of a human monoclonal IgA1 (Mem) was established, in part by analogy with already known sequences. By homology its variable part was shown to belong to the V lambda I subgroup while the isotype-associated amino acid residues characterized it as Mcg+, Kern+ and Oz-. The normal primary structure of this chain was in contrast to its abnormal physical and antigenic properties: (a) its apparent molecular mass estimated by SDS/polyacrylamide gel electrophoresis, by gel filtration chromatography and by gradient ultracentrifugation was found to be lower by approximately equal to 10% than the values (23.5 kDa) of 'normal' light chain used as controls; (b) the lambda I chain Mem, when tested in native state was not antigenically reactive. These abnormalities were reverted when the chain was treated with 8 M urea. These data suggest that the abnormal behaviour of lambda I chain Mem is at a conformational level.

The primary structure of mu-chain-disease protein BOT. Peculiar amino-acid sequence of the N-terminal 42 positions.

The complete primary structure of the mu heavy-chain disease (mu-HCD) protein BOT has been determined. The monomeric HCD-mu-chain consists of 391 amino-acid residues, lacking the VH and mu CH1 domains but including the entire CH2, CH3 and CH4 domains (349 residues). The sequence of the preceding 42 N-terminal residues which we designate as the "pre-C-part" presents no homology to any known variable or constant immunoglobulin sequence, but contains an internal homology of positions 10-19 to positions 20-29. The origin of the "pre-C-part" structure and the deletion of the mu CH1 domain of protein BOT are discussed.

Biochemical and biosynthetic studies of a crystallizable human gamma 1 heavy-chain disease protein.

We have studied the structure of a crystallizable gamma 1 heavy-chain disease protein that lacks the entire VH and C gamma 1 domains. The protein starts within the hinge region at aspartic acid 221 (Eu numbering). The native protein is a disulphide-linked dimer with an apparent molecular weight of 52,000, consistent with the biochemical data obtained on the whole protein and its cyanogen bromide fragments. The carbohydrate content of this protein was 6.8%. As shown by biosynthesis experiments intracytoplasmic gamma chains synthesized by neoplastic cells had an apparent molecular weight similar to that of the serum heavy-chain disease protein. These data are compared with those obtained for other gamma 1 heavy-chain disease proteins beginning in the hinge region, and the mechanisms leading to those abnormal Ig products are discussed.

Crystals of the human heavy chain disease protein Riv and human Fc fragment are isomorphous: further evidence for conformational flexibility in the hinge region of immunoglobulins.

Protein Riv is a human gamma 1 heavy chain disease immunoglobulin variant with a deletion of the entire VH and CH1 domains and consisting of most of the hinge region plus the CH2 and CH3 domains. Crystals of this protein are orthorhombic, belonging to the space group P2(1)2(1)2(1), with a = 80.1 A, b = 145.5 A, c = 50.1 A. These crystals are shown to be isomorphous with crystals of a human Fc fragment, indicating that the hinge region and the initial part of the CH2 domain of protein Riv do not assume a unique conformation in the crystalline state.

[Light chain or monoclonal immunoglobulin deposition disease: physiopathogenic concepts]. / La maladie des dépôts de chaînes légères ou d'immunoglobulines monoclonales: concepts physiopathogéniques.

Although recently identified, this disease is by no means exceptional. It is characterized by the deposition in various organs of an amorphous substance which differs from the amyloid substance and contains monoclonal immunoglobulin determinants: either a light kappa or lambda chain, or a light and a heavy chain. The severity of the disease is due to various organs being involved, notably the kidneys. There is in every case a monoclonal plasmocytic or lymphoplasmocytic proliferation which may appear as benign. In almost one-third of the cases no monoclonal immunoglobulin can be detected in the serum. In a study of immunoglobulin biosynthesis, 6 out of 8 patients showed striking structural abnormalities. The relationship between these very unusual lg's and tissue deposition is discussed in detail.

Monosaccharide composition of human monoclonal (18) and normal (8) IGM immunoglobulins: proposed structural models for their glycan chains.

The carbohydrate composition of 18 monoclonal IgM (Waldenström macroglobulinemia) was determined by gas-liquid chromatography. Two populations occurred with mean sugar contents of 7.3% (12 IgM and 10% (6 IgM). A value of 7.2% was obtained for 8 IgM prepared from 8 normal sera. On the basis of mean molar ratios established for each monosaccharide residue, structural models for oligosaccharide units are proposed. The number of complex glycan chains (N-acetyllactosaminic type) is higher in the 10% population, which would correspond to IgM with a mean sedimentation constant of 18.3So20, W. On the other hand, the 7.3% population has a lower content of "mature" chains and its sedimentation constant would be inferior: 17S)20, W.

Regulation of the human allogenic proliferative response in vitro. II. Production of soluble suppressor factors by suppressor T cells and evidence in favor of "acceptor" cells for suppression among unprimed lymphocytes.

It has previously been shown that presensitized cells in culture medium release suppressor factors (SF) which can inhibit a primary mixed leukocyte reaction (MLR I). This occurs when the presensitized cells are resensitized with an HLA-DR-specific cell, which can be either the primary stimulator or any other DR-identical allogeneic cell. The autologous responders (SF producer cells) and certain allogeneic cells are suppressed, which suggests that restriction takes place. In this paper the effect of preincubation of responder or stimulator cells in SF has been studied: (1) When unprimed responders are preincubated with the suppressor supernates (SF) and tested in MLR I against several stimulators, the cells of the autologous SF producer and certain other allogeneic cells are always inhibited as already observed when SF was added directly to a mixed lymphocyte culture. (2) When the same stimulators are preincubated with the same SF and used as stimulators with the same responders (not preincubated) then inhibition is observed without restriction. This difference in behavior suggests the existence of at least two factors, one acting through stimulators on all responders. (3) Filtration of unprimed responders through glass wool (before SF preincubation and coculture with stimulators in MLR I) produces nonadherent T cells which are suppressed more after preincubation with SF than the same cells unfiltered. This could be due to the existence of a subset of "acceptor" cells. (4) None of these factors has immunoglobulin characteristics. Their molecular weights are between 40 000 and 70 000 daltons.

The primary structure of the constant part of mu-chain-disease protein BOT.

The complete primary structure of the constant part of the mu-chain-disease protein, BOT, was established. It includes the whole CH2, CH3 and CH4 domains. two amino acid changes were found, at positions 309 (Ser leads to Gly) and 333 (Val leads to Gly) (GAL numbering). In two additional monoclonal mu chains (SCO and CO), the same positions showed an amino acid variability. From these data it may be concluded that four types of mu chains exist in the human: (1) GAL type with Ser-309 and Val-333; (2) OU type with Gly-309 and Val-333; (3) SCO type with Ser-309 and Gly-333; (4) BOT/CO type with Gly-309 and Gly-333. The meaning of this molecular polymorphism is discussed.

[Localization of binding sites in the hemoglobin-haptoglobin complex]. / Localisation des surfaces de contact du complexe hémoglobine-haptoglobine.

The binding and specific elution of Hb peptides from Hp was studied. Our results were confirmed by the study of inhibition of binding of alpha chains to Hp. In conclusion, a model of contact areas of Hp-Hb complex is proposed.

Binding properties of goat IgM anti-dinitrophenyl antibodies.

Goats immunized over 2 months with low doses of 1 mg/kg of dinitrophenylated Salmonella typhimurium responded with low levels of anti-DNP antibodies restricted to the IgM class. The purified antibodies show low association constants (Ka between 10(4) of 10(5) l/M), a high degree of homogeneity (heterogeneity indices alpha between 0.7 and 0.9) and ten combining sites when tested against dinitrophenyl-lysine as ligand by equilibrium dialysis. These binding properties remained unchanged during the whole immune response. When after 9 months the animals received the same immunogen and DNP-BGG, the anti-DNP antibody response included antibodies in the IgG class.

Binding of human hemoglobin and its polypeptide chains with haptoglobin coupled to an agarose matrix.

The interactions of human haptoglobin covalently linked to agarose with human hemoglobin and with p-chloromercuribenzoic-acid-treated alpha and beta chains (alpha* and beta* chains) were studied by flow chromatography and equilibrium binding. The results indicate that in solid state, haptoglobin maintains the same binding characteristics as in solution, the order of binding affinities being: hemoglobin greater than alpha* chain greater than beta* chain. The study of the binding parameters of the alpha* chain shows an heterogeneity of binding sites on the haptoglobin and an average affinity constant Ka of 3.6 X 10(4)l/mol.

A new case of heavy mu-chain disease.

The tenth case of mu chain disease is described. The patient lives in Ivory Coast as in our previously reported case. He was not affected with chronic lymphocytic leukaemia and the main clinical feature was liver cirrhosis of unknown origin. The amount of abnormal protein in the serum was great enough to give an abnormal bond on the routine electrophoresis. The protein was devoid of light chains and was present in the form of disulfide linked polymers of incomplete mu chain. The molecular weight of the monomer was approximately 58,000. The protein comprised the Fc fragment and a part of the Fd segment. Bence Jones protein was not found in the urine.