TWO MAJOR TYPES OF NORMAL 7S gamma-GLOBULIN

Bio-nanocapsules displaying various immunoglobulins as an active targeting-based drug delivery system

The bio-nanocapsule (BNC) is an approximately 30-nm particle comprising the hepatitis B virus (HBV) envelope L protein and a lipid bilayer. The L protein harbors the HBV-derived infection machinery; therefore, BNC can encapsulate payloads such as drugs, nucleic acids, and proteins and deliver them into human hepatocytes specifically in vitro and in vivo. To diversify the possible functions of BNC, we generated ZZ-BNC by replacing the domain indispensable for the human hepatotrophic property of BNC (N-terminal region of L protein) with the tandem form of the IgG Fc-binding Z domain of Staphylococcus aureus protein A. Thus, the ZZ-BNC is an active targeting-based drug delivery system (DDS) nanocarrier that depends on the specificity of the IgGs displayed. However, the Z domain limits the animal species and subtypes of IgGs that can be displayed on ZZ-BNC. In this study, we introduced into BNC an Ig κ light chain-binding B1 domain of Finegoldia magna protein L (protein-L B1 domain) and an Ig Fc-binding C2 domain of Streptococcus species protein G (protein-G C2 domain) to produce LG-BNC. The LL-BNC was constructed in a similar way using a tandem form of the protein-L B1 domain. Both LG-BNC and LL-BNC could display rat IgGs, mouse IgG1, human IgG3, and human IgM, all of which not binding to ZZ-BNC, and accumulate in target cells in an antibody specificity-dependent manner. Thus, these BNCs could display a broad spectrum of Igs, significantly improving the prospects for BNCs as active targeting-based DDS nanocarriers.

STATEMENT OF SIGNIFICANCE

We previously reported that ZZ-BNC, bio-nanocapsule deploying the IgG-binding Z domain of protein A, could display cell-specific antibody in an oriented immobilization manner, and act as an active targeting-based DDS nanocarrier. Since the Z domain can only bind to limited types of Igs, we generated BNCs deploying other Ig-binding domains: LL-BNC harboring the tandem form of Ig-binding domain of protein L, and LG-BNC harboring the Ig binding domains of protein L and protein G sequentially. Both BNCs could display a broader spectrum of Igs than does the ZZ-BNC. When these BNCs displayed anti-CD11c IgG or anti-EGFR IgG, both of which cannot bind to Z domain, they could bind to and then enter their respective target cells.

LOCALIZATION OF ANTIBODIES IN GROUP I AND GROUP II GAMMA-GLOBULINS

A wide assortment of antibodies has been analysed by qualitative and quantitative techniques for their content of group I- and group II-type γ-globulin molecules. These included Rh antibodies, isoagglutinins, thyroglobulin antibodies, dextran antibodies, and teichoic acid antibodies. All the antibodies studied showed the presence of both groups. However, the ratio of the two varied widely in different individuals and diverged markedly from the ratio in the total γ-globulin of the individual. Two antibodies isolated from the serum of the same individual showed different ratios for the two groups.

H CHAIN SUBGROUPS OF MYELOMA PROTEINS AND NORMAL 7S GAMMA-GLOBULIN

Through the use of a variety of antisera to isolated myeloma proteins, four subgroups of 7S gamma-globulin type proteins were readily distinguished. The first, the Vi subgroup, consisted of ten of 64 myeloma proteins studied. The second, the We group, contained the majority of myeloma proteins. The third, the Ge subgroup, included three of 50 myeloma proteins. The fourth remains ill-defined and appears heterogeneous. Counterparts for both the Vi and the Ge subgroup, were found in the Fr II gamma-globulin and in the normal gamma-globulin of all of a large number of individual sera studied. The unique antigenic character of both groups was localized to the H chains, although different determinants were involved for different antisera. An essential role of intact disulfide bonds was apparent with certain rabbit antisera. In addition to the special antigenic characteristics, the Ge subgroup showed in each instance a fast mobility for the F fragments produced by papain which was not found for other myeloma proteins.

STRUCTURAL ASPECTS OF HUMAN ERYTHROCYTE AUTOANTIBODIES. I. L CHAIN TYPES AND ELECTROPHORETIC DISPERSION

The 7S gamma-globulins causing erythrocyte autosensitization in 20 patients were isolated by elution and examined for homogeneity or heterogeneity of their L chain types and electrophoretic dispersion. The isolated erythrocyte autoantibodies from 12 patients contained only 1 detectable L chain type. Two of these "monotypic" populations showed appreciable restriction of electrophoretic dispersion, while 2 others more nearly resembled the electrophoretic heterogeneity of normal gamma-globulins. The autoantibodies from the other 8 patients exhibited L chains of both types. The single "bitypic" population so tested was relatively polydisperse electrophoretically. As a comparison, anti-Rh(o) isoantibodies from 5 of 6 donors without known hematologic disease showed bitypic reactions, and 2 of these isoantibody populations were relatively polydisperse electrophoretically. One Rh isoantibody is described which contained only 1 demonstrable L chain type. The structural similarities to "paraproteins" observed in a significant proportion of these erythrocyte autoantibodies raise the possibility of their origin from a restricted population of antibody forming cells, and may have implications concerning the pathogenesis of erythrocyte autosensitization.

STUDIES ON HUMAN ANTIBODIES. II. DISTRIBUTION OF GENETIC FACTORS

Human antibodies against dextran, teichoic acid, blood group A substance, levan, tetanus toxoid, and nuclei were isolated and analyzed for their content of Gm(a), Gm(b), and Inv(a) γ-globulin genetic factors. The majority of these antibodies contained all the genetic factors determined in the donor's whole γ-globulin, but in many antibodies at very different concentrations. In a few instances specific factors could not be detected despite their presence in the individual's whole γ-globulin. Different antibodies isolated from the serum of the same individual showed different relative concentrations of genetic factors. The distribution of genetic factors seen in certain isolated human antibodies appeared to approach the selective occurrence of these factors in myeloma proteins.

NATURALLY OCCURRING HUMAN ANTIBODY REACTING WITH BENCE JONES PROTEINS

Agglutinating substances having characteristics of naturally occurring macroglobulin antibodies to human Bence Jones proteins have been identified in human sera. By means of hemagglutination and hemagglutination inhibition techniques, common determinants have been demonstrated on the light (L) polypeptide chains of pooled normal human γ₂-globulin and on some Bence Jones proteins of group 1 but not of group 2. Individual human sera serve to delineate subgroups of the two major antigenic groups of the Bence Jones proteins by agglutinating cells coated by one but not another protein of the same antigenic group. The complexity of subgroups, especially of group 2, is established by testing a panel of Bence Jones proteins of the same group for their ability to inhibit hemagglutination. By this means it appeared that different sera recognized different group-specific determinants of cells coated with a single Bence Jones protein. The capacity of the L polypeptide chains and proteolytic fragments of γ₂-globulin to inhibit the hemagglutination reaction between Bence Jones protein or L chain-coated cells and human sera was examined. These studies demonstrated that the determinants, toward which agglutinators of human serum are directed, appear to be blocked in intact γ₂-globulin and in all fragments in which H chain remains in proximity to L chain. It would appear that the presence of H chains bound to L chains by non-covalent bonds completely obstructs the reactivity of the involved L chain groups. The agglutinating capacity of a serum toward Bence Jones proteins or L chains of γ₂-globulin appeared to be independent of its agglutinating capacity for cells coated with intact γ₂-globulin. No correlation of the presence in serum of agglutinators for Bence Jones proteins or L chains with health or disease has been established.

A STUDY OF RABBIT GAMMA-GLOBULIN ALLOTYPY BY MEANS OF HETEROIMMUNIZATIONS

Representatives of two species, the chicken and the goat, were immunized by injection with Freund's adjuvant, of specific precipitates prepared from the antisera of rabbits with various allotypic specificities. The precipitation reactions of the resulting antisera with normal rabbit sera were studied in liquid and in gellified media. In these reactions the isotypic specificity and often one or the other of the allotypic specificities of rabbit gamma-globulin were involved. It was always easier to obtain antibodies against the specificities controlled by the alleles of locus b (Ab4, Ab5, Ab6) than of locus a (Aa1, Aa2, Aa3). The precipitation reaction of antibodies against a specificity of the a series could always be inhibited by an excess (nearly always moderate) of a serum lacking this specificity. A similar inhibition of the antibodies against the specificities of the b series was often impossible, especially if the antiserum had been collected after a second injection of immunizing material. The reactions of 58 Ab4(+) sera with a goat anti-Ab4 serum and of 28 Ab5(+) sera with a chicken anti-AbS serum were studied in gel tubes (simple diffusion). The constant observation of two precipitation zones due respectively to two types of molecules, Ab4(+) and Ab4(-) (or Ab5(+) and Ab5(-)), indicated the existence of an appreciable number of Ab4(-) or Ab5(-) molecules, even in supposed homozygotes. In the latter rabbits Ab4(-) or Ab5(-) molecules are b(-) molecules; i.e., molecules lacking the specificities of the b series. Measurements of the distances between the two zones in the reaction of 72 sera revealed significant differences between sera of individuals of the same phenotype, as well as systematic differences not only between sera of homozygotes and of heterozygotes, but also between heterozygotes of different genotypes. These measurements were used to evaluate the ratio of concentrations of the two types of molecules detected by each of the two antisera. The occurrence of b(-) molecules in every one of the fairly large number of sera studied indicates a new aspect of the heterogeneity of gamma-globulin. Although detected by means of allotypy, this heterogeneity is not dependent upon factors which vary with individuals. These results are discussed in connection with what is known of the structure of gamma-globulin.

THE IMMUNOGLOBULINS OF MICE. I. FOUR MAJOR CLASSES OF IMMUNOGLOBULINS: 7S GAMMA-2-, 7S GAMMA-1-, GAMMA-1A (BETA-2A)-, AND 18S GAMMA-1M-GLOBULINS

Two classes of 7S γ-globulins are identified in normal mouse serum and are designated 7S γ₂-globulins and 7S γ₁-globulins. These two immunoglobulin classes are similar in size. They differ in range of electrophoretic mobility, in specific antigenic determinants, and in genetically determined isoantigens. Four classes of immunoglobulins in mouse serum, i.e. 7S γ₂-, 7S γ₁-, γ_1A (β_2A), and γ_M-globulins, were shown to have antibody activity. Each class was characterized and shown to have distinctive immunochemical and physicochemical properties. The genetically determined isoantigens, Iga-1 and Iga-2, were shown to be present only on 7S γ₂-globulin molecules.

STUDIES ON HUMAN ANTIBODIES. 3. AMINO ACID COMPOSITION OF FOUR ANTIBODIES FROM ONE INDIVIDUAL

Antilevan, antidextran, antiteichoic acid, anti-"A" and normal γG, all isolated from a single human, as well as pooled γG and γM, were analyzed for amino acid content. Differences ranging from 7 to 32 residues were found among these antibodies in glycine, valine, leucine, tyrosine, arginine, lysine, and threonine content. These conspicuous differences in amino acid composition were not correlated with the Gm type of these antibodies. Hydroxylysine was found in two of the four antibodies, antidextran and antiteichoic acid, and in γM- immunoglobulin. No hydroxylysine was found in γG- globulins. These findings probably account for discrepancies in the literature concerning the occurrence of this residue in antibody protein.

EQUINE ANTIHAPTEN ANTIBODY. I. 7S BETA-2A- AND 1OS GAMMA-1- GLOBULIN COMPONENTS OF PURIFIED ANTI-BETA-LACTOSIDE ANTIBODY

Anti-p-azophenyl-β-lactoside (Lac) antibody has been isolated from equine antiserum by specific precipitation with Lac-HSA (human serum albumin) and Lac-Hy (hemocyanin). Antibody was separated from antigen by chromatography on DEAE cellulose and zone electrophoresis in solvents containing lactose. Six antigenically distinct immunoglobulins have been identified in purified equine anti-Lac antibody: 7S β_2A-globulin, 19S γ-globulin, a 10S γ₁ globulin, and three antigenically distinct 7S γ-globulins. The specific hapten-binding activity of the 7S β_2A-antibody and of the 10S γ₁-antibody has been demonstrated by equilibrium dialysis and by analytical ultracentrifugation using a combination of schlieren and absorption optics. The 10S γ₁-globulin antibody may be representative of a hitherto undescribed class of immunoglobulins.

Analysis of immunoglobulins secreted by hybridomas derived from rheumatoid synovia

Twenty-six IgG-secreting and eight IgM-secreting hybridomas were derived from the synovia of two patients with rheumatoid arthritis (RA). Hybridomas were obtained by fusing a heteromyeloma cell line, SPAZ-4 with synovial mononuclear cells that were not deliberately stimulated in vitro. Over 96% of the IgG-secreting hybridomas produced antibodies which belonged to the IgG1 subclass and showed lambda light chain predominance; the latter was not seen in IgM antibodies, where kappa light chains dominated by 3:1. All IgG antibodies were cationic. Synovial B cells were not exposed to extrinsic stimuli prior to fusion, therefore these results reflect the state of B cell activation and differentiation in vivo. Our results indicate that IgG-secreting B cells in the RA joint are under a selective influence which is, as yet, unidentified. One out of eight IgM-secreting and two out of 26 IgG-secreting hybridomas produced rheumatoid factors (RF). The IgM-RF specificity for IgG heavy chain subclasses was determined and showed that the monoclonal bound to IgG1, IgG2 and IgG4 but not IgG3 with exception of IgG3 Goe of the G3m (st) allotype, a profile typical of specificity for the Ga epitope. This monoclonal also distinguished a determinant in the Fc region of human IgG which was not present in rabbit IgG. The overall frequency of RF-secreting hybridomas we observed indicates that B cells committed to RF production in the synovium of a seropositive and a seronegative RA patient is below 10%.

Membrane-associated immunoglobulin determinants on bone marrow and blood lymphocytes in the pediatric age group and on fetal tissues

Lymphocytes from bone marrow and blood of infants and children and from various tissues of seven fetuses between 13 and 25 weeks of gestational age were studied by immunofluorescence for the presence of membrane-associated immunoglobulins. Cells with mu and delta determinants prevailed, and these immunoglobulins were usually present on the same cell. The bone marrow specimens of all age groups contained more mu-positive cells without delta determinants than did the samples from the peripheral blood. Such mu(+)delta(-) cells were also found in tissues of young fetuses. These cells were postulated to represent the first stage of B cells displaying Ig receptors. Other tests with double staining showed that cells with delta determinants, but without the presence of other H chains, are rare, if they exist at all. This finding supports the idea that the role of IgD could be one of regulation of antibody secretion rather than of antibody activity. The number of cells that displayed alpha determinants was first observed to rise after birth, and only in the bone marrow, where it reached an average maximum of 16%. The relative number of such cells in the blood never exceeded a few percent.

Interactions between ricinus agglutinin and human IgM and IgG

Ricinus agglutinin, purified until homogeneous, precipitates serum glycoproteins with terminal nonreducing galactose residues including IgM and IgG. Almost 100% of IgM reacted with anti-IgM and ricinus agglutinin in quantitative precipitin tests. In similar tests, almost 100% of polyclonal IgG was precipitated by excess anti-IgG, whereas only about 10% reacted with ricinus agglutinin. In quantitative precipitin analyses and affinity chromatography experiments with insolubilized ricinus agglutinin and isolated monoclonal IgG1 and IgG3 proteins, only IgG3 proteins reacted with ricinus agglutinin.

Urinary Immunoglobulin Components in Normal, Tubular, and Glomerular Proteinuria: Quantities and Characteristics of Free Light Chains, IgG, IgA, and Fcγ Fragment

The urinary excretion of free light immunoglobulin chains IgG, IgA, and Fcγ fragment material has been estimated in 12 healthy individuals and 7 subjects with tubular or glomerular proteinuria. Measurements were carried out by immunochemical methods after separation of concentrated urinary immunoglobulin components by gel chromatography. Various components were isolated and their sedimentation constants, Stokes' radii, diffusion coefficients, molecular weights, and frictional ratios were determined.-Twenty-four hour urine volumes from the healthy subjects contained, on average, 3.3 mg of free light chains, 3.0 mg of IgG, approximately 2.0 mg of IgA, and 0.19 mg of Fey fragment Material. Normal urinary IgA included about 90% 11.5 S IgA of molecular weight 370000 and about 10% 7.0 S of molecular Weight 165000.-Patients with tubular proteinuria excreted relatively more of immunoglobulin components of small size than the patients with glomerular proteinuria. In particular, urine from patients with tubular proteinuria contained more free light chains than IgG whereas urine from patients with glomerular proteinuria contained more IgG than free light chains. The excretion of free light chains in the patients with tubular proteinuria was 8 to 33 times the average normal value. The results indicate an excess normal production of light chains assuming that all or most of the free chains originate from de novo synthesis. The relative amounts of urinary 11.5 S and 7.0 S IgA were similar in tubular proteinuria and normal proteinuria, whereas relatively more urinary 7.0 S IgA was found in glomerular proteinuria. This observation and the properties of the two IgA species suggest that the 11.5 S IgA is secretory IgA from the urinary tract and that most or all of the 7.0 S IgA originates from plasma.

Antigenic specificities related to the cold agglutinin activity of gamma M globulins

Certain antiserums prepared against isolated cold agglutinins demonstrate specificity for gamma M globulins with this activity and not for similar gamma M globulins lacking such activity. The cold agglutinin specific antigens fall into several major and minor groups. Their exact relation to the presumed antibody-combining sites remains to be determined.