Membrane immunoglobulins and antigen receptors on B and T lymphocytes

Artificial Immune System-Negative Selection Classification Algorithm (NSCA) for Four Class Electroencephalogram (EEG) Signals

Artificial immune systems (AIS) are intelligent algorithms derived from the principles inspired by the human immune system. In this study, electroencephalography (EEG) signals for four distinct motor movements of human limbs are detected and classified using a negative selection classification algorithm (NSCA). For this study, a widely studied open source EEG signal database (BCI IV-Graz dataset 2a, comprising nine subjects) has been used. Mel frequency cepstral coefficients (MFCCs) are extracted as selected features from recorded EEG signals. Dimensionality reduction of data is carried out by applying two hidden layered stacked auto-encoder. Genetic algorithm (GA) optimized detectors (artificial lymphocytes) are trained using negative selection algorithm (NSA) for detection and classification of four motor movements. The trained detectors consist of four sets of detectors, each set is trained for detection and classification of one of the four movements from the other three movements. The optimized radius of detector is small enough not to mis-detect the sample. Euclidean distance of each detector with every training dataset sample is taken and compared with the optimized radius of the detector as a nonself detector. Our proposed approach achieved a mean classification accuracy of 86.39% for limb movements over nine subjects with a maximum individual subject classification accuracy of 97.5% for subject number eight.

IgE Production after Four Routes of Injections of Japanese Cedar Pollen Allergen without Adjuvant: Crucial Role of Resident Cells at Intraperitoneal or Intranasal Injection Site in the Production of Specific IgE toward the Allergen

The production of specific IgE antibodies directed toward cedar pollen correlates well with the onset of allergic rhinitis; but the mechanisms of allergen recognition as nonself and Ig class switch to IgE by the immune system are still not fully understood. In the present study, we injected cedar pollen into mice through 4 different routes (intranasal (i.n.), intraperitoneal (i.p.), intravenous (i.v.), and subcutaneous (s.c.)) without adjuvant 1 to 3 times, and determined time-dependent changes in the total and specific serum IgE levels compared with those in the serum levels of other isotype Igs. After an i.p. or i.n. injection of allergen into the mice, they produced a 1.5-to 1.7-fold increase in total IgE, but none in IgG, IgM, or IgA antibodies in their serum, whereas an i.v. or s.c. injection of allergen was inactive as an inducer of total IgE antibodies. Upon a 2nd (s.c.) injection of the allergen into the i.p. or i.n. sensitized mice, a large amount of allergen-specific IgE antibodies was found in the serum. In the case of i.v. or s.c. sensitized mice, however, they produced total, but not specific, IgE antibodies; and a 3rd (s.c.) injection of the allergen resulted in a large amount of specific IgE antibodies in the serum. These results imply that resident cells at the i.p. or i.n. injection site may play a crucial role in the efficient production of total and specific IgE antibodies toward the allergen.

Differences between the Fc receptors of two lymphocyte subpopulations of human peripheral blood

The Fc receptors of human peripheral blood lymphocytes bearing stable membrane Ig (B cells) and those bearing cytophilic membrane Ig (UL cells) were evaluated for binding avidity and interaction with human 'Ia-like' alloantigens. Titration experiments showed that binding of soluble antigen-antibody complexes to UL cells was readily detected at low concentations (5-10 microgram/ml), whereas high concentrations (400-800 microgram/ml) were necessary to detect binding to most B lymphocytes. Binding at all concentrations was dependent on an intact Fc portion of the antibody molecule within the antigen-antibody complex. F(ab')2 fragments of antibodies against human 'Ia-like' antigens inhibited binding of complexed Ig to B cells but not UL cells. These differences are compatible with the possibility that the Fc receptors of the two cell populations are distinct molecular entities or, alternatively, are the same molecules and differ in quantity, distribution, or mobility on the surface of the two cell types.

Early B-cell factor, E2A, and Pax-5 cooperate to activate the early B cell-specific mb-1 promoter

Previous studies have suggested that the early-B-cell-specific mb-1(Igalpha) promoter is regulated by EBF and Pax-5. Here, we used in vivo footprinting assays to detect occupation of binding sites in endogenous mb-1 promoters at various stages of B-cell differentiation. In addition to EBF and Pax-5 binding sites, we detected occupancy of a consensus binding site for E2A proteins (E box) in pre-B cells. EBF and E box sites are crucial for promoter function in transfected pre-B cells, and EBF and E2A proteins synergistically activated the promoter in transfected HeLa cells. Other data suggest that EBF and E box sites are less important for promoter function at later stages of differentiation, whereas binding sites for Pax-5 (and its Ets ternary complex partners) are required for promoter function in all mb-1-expressing cells. Using DNA microarrays, we found that expression of endogenous mb-1 transcripts correlates most closely with EBF expression and negatively with Id1, an inhibitor of E2A protein function, further linking regulation of the mb-1 gene with EBF and E2A. Together, our studies demonstrate the complexity of factors regulating tissue-specific transcription and support the concept that EBF, E2A, and Pax-5 cooperate to activate target genes in early B-cell development.

Cross-reactions of anti-immunoglobulin sera with synthetic T-cell receptor beta peptides: mapping on a 3-dimension model

The derived amino acid sequences of human T-cell receptor beta chain shows significant homology to lambda light chains of immunoglobulins in its variable, joining, and constant regions. We assessed the cross-reactivity between Tcr beta chains and immunoglobulin light chains by determining the capacity of rabbit antisera to human or murine immunoglobulins to react to a synthesized set of nested, overlapping 16-mer peptides corresponding to the VDJC sequence of the Tcr beta chain YT35. The observed reactivities were consistent with homologies to lambda and kappa light chains, the strongest reactivity being with a peptide that corresponds to the "switch peptide" of light chains, as assessed by ELISA binding and competitive inhibitions assays. Other regions reactive with anti-light chain sera corresponded to CDR1 and Fr3 segments of the variable domain and a segment of the constant region predicted to loop out of the tight globular structure. The peptide immunochemical results, together with the identification of specific regions of sequence correspondence between Tcr beta and the characterized lambda light chain Mcg, allowed us to develop a 3-dimensional model of the beta chain consistent with its role in antigen recognition.

Shared antigenic determinants of immunoglobulins in phylogeny and in comparison with T-cell receptors

1. Immunoglobulins are a complex multigene family of proteins specified by genes encoding variable (V), sometimes diversity (D), joining (J), and constant (C) domains. 2. Cross-reactions involving conformational determinants related to the VHa system of rabbits occur on heavy chains of vertebrate species ranging from elasmobranchs to man. 3. Serological markers characteristic of mu chains, the heavy chain of the IgM macroglobulins, occur on homologous heavy chains of species representing all vertebrate classes. 4. Serological markers characteristic of gamma type heavy chains, the major isotype in man, are restricted to the mammals, but are found on representatives of even the most primitive mammals, the egg-laying monotremes. 5. Variable region markers characteristic of lambda light chains are shared by light chains of shark and man. 6. Certain idiotypic markers defined by combining site V region sequences are broadly distributed in evolution. 7. Use of synthetic peptides as antigens and in epitope mapping show that amino acid sequences from the third framework region of the variable domain are broadly shared among light chain in phylogeny and between light chains and T-cell receptor beta chains. 8. The "switch peptides" linking the V and C domains of light chains and T-cell receptors, specified by the C-terminal portion of the J segment and the N-terminus of the constant region, are exposed in the three-dimensional structure of immunoglobulin or Tcrs, show striking homology, and form broadly shared antigenic determinants characteristic of immunoglobulins. 9. Although the multigene nature of the immunoglobulins and the complexity of antigenic determinants expressed by these large proteins renders comparison among molecules difficult, serum immunoglobulins and the closely related T-cell receptors express numerous shared determinants defined on the basis of amino acid sequence homology and three-dimensional conformations.

Purification of immunoglobulin production stimulation factor II alpha derived from Namalwa cells

An immunoglobulin production stimulating factor (IPSF) in human lymphoblastoid Namalwa cells was purified by the serial use of ammonium sulfate fractionation, hydrophobic interaction chromatography and gel filtration, and named IPSF-II alpha. IPSF-II alpha was estimated as a 112 KD protein composed of a 40 KD polypeptide and two 36 KD polypeptides. The 36 KD protein extracted from SDS-polyacrylamide gel showed IPSF activity, but not the 40 KD protein. The IPSF activity was reasonably stable in alkaline but unstable in acidic solution and heat-unstable. In a serum-free medium, IPSF-II alpha stimulated IgM production of human-human and mouse-mouse hybridomas 4-15 and 2-fold, respectively, although its growth stimulatory effect on hybridomas was negligible. The factor did not stimulate IgG production in either human or mouse hybridomas in the same serum-free medium. These results suggested that IPSF-II alpha was a new cellular factor for stimulating IgM productivity of hybridomas.

Analysis of immunoglobulin isotype blood levels, splenic B-cell phenotypes, and spleen cell immunoglobulin gene expression in mice infected with lactate dehydrogenase-elevating virus

B-lymphocyte activation was studied in mice infected with lactate dehydrogenase-elevating virus (LDV). ELISA determinations of blood total immunoglobulin levels demonstrated that, at 10 days post-infection (p.i.) with LDV, only the IgG2a isotype was elevated. DNA-excess dot-blot hybridization showed that RNA specific for IgG2a and IgA immunoglobulin isotypes was increased in the spleens of mice at 10 days p.i. with LDV. Immunoglobulin surface phenotype analysis of spleen cells at 8-10 days p.i. with LDV revealed that there was no alteration in immunoglobulin isotype-bearing cell proportions, although total spleen mass and number of cells increased during LDV infection. When blood immunoglobulins from LDV-infected mice were analyzed by two-dimensional isoelectric focusing gels, followed by specific immunoblotting for immunoglobulin isotype, the presence of new IgG2a species was observed at 10 days p.i.

Antibodies to synthetic peptides corresponding to variable-region first-framework segments of T cell receptor. Detection of T cell products and cross-reactions with classical immunoglobulins

Recent studies at the gene level have shown that T cells express rearranged genes for four types of T cell receptors that are strongly homologous to classical immunoglobulins in the joining region and in the framework 1 (Fr1) and 3 segments of the variable region. Based upon the homologies in gene sequence, it follows that the gene products would show similarities in amino acid sequence and in the folding of the proteins so that cross-reactivities in antigenic determinants would be expected between variable regions of the T cell receptors and classical immunoglobulins. We have synthesized peptides corresponding to predicted protein sequences of the Fr1 residues of T cell receptor alpha, beta- and gamma-chains and have produced antibodies in rabbits against these synthetic peptides. Use of antisera and affinity-purified antipeptide antibodies indicated that high-titer antibodies could be raised that were specific for individual Fr1 peptides. Cross-reactions among Fr1 peptides of T cell receptors and immunoglobulin light chains were observed. In addition, some rabbit antisera raised against classical polyclonal immunoglobulins or affinity-purified immunoglobulin-like T cell receptors were found to exhibit binding activity against Fr1 peptides of T cell receptor beta- and gamma-chains. The sequence homology, although real among the Fr1 of T cell receptors and immunoglobulin light chains, is moderate and the antigenic cross-reaction must reflect the configuration and types of amino acids present. The development of antipeptide antibodies holds promise for the characterization of T cell receptors of various T cell sources and also offers a new means for the identification of molecules related to rearranging immunoglobulins.

A monoclonal antigen-binding T cell immunoprotein: antigenic relatedness to T cell receptor beta chain FR1 V and J peptide segments: physicochemical distinctiveness from classical immunoglobulins and T cell receptor heterodimers

The monoclonal murine T cell hybridoma, 51H7D, was previously shown to bind the arsazobenzene hapten and to produce a soluble antigen-binding molecule. In this paper we characterize this antigen-binding immunoprotein for its relationship to known T cell receptors serologically, using antibodies specific for variable region framework, or joining region peptides predicted from gene sequence and by biochemical means. The 51H7D cell expresses a protein with subunit size of approximately 31,000, that reacts antigenically with affinity-purified antibodies directed against synthetic first framework and joining segment peptides, corresponding to the gene sequence of the T cell receptor beta chain, YT35. This molecule does not react with affinity-purified antibodies directed against murine immunoglobulin, framework 1 sequences of alpha and gamma T cell receptors, or with antibodies against synthetic heavy chain joining segments. The subunit of mol. wt. 31,000 can form higher aggregates, notably in the mol. wt range of 60,000-70,000, depending upon extraction conditions. The soluble form of the antigen-binding molecule bears the J beta cross-reactive determinant and occurs predominantly as a charge restricted molecular species of approximate mol. wt 60,000-70,000. The purified molecule has a blocked N-terminus, but quantitative statistical analysis of its amino acid composition indicates a closer relatedness to T cell receptor beta chains and other antigen-binding T cell products, than it has to alpha, gamma or delta TCR chains. No evidence for more than one type of polypeptide chain was found and the polymerization is not dependent upon the formation of disulfide bonds. These studies raise the possibility that antigen-binding soluble T cell molecules might belong to a new family of immunoproteins, that is related to, but distinct from, classical immunoglobulins and alpha beta or gamma delta heterodimers.

Immunoglobulin epitopes defined by synthetic peptides corresponding to joining region sequence: conservation of determinants and dependence upon the presence of an arginyl or lysyl residue for cross-reaction between light chains and T-cell receptor chains

Joining or J region sequences of rearranging immunoglobulins and T-cell receptors show considerable sequence homology, particularly in their C-terminal portion corresponding to the fourth framework region of immunoglobulin variable regions. In order to test the question of whether serological cross-reactions between immunoglobulin variable regions and T-cell receptors were due to antigenic similarities in their J regions, we synthesized synthetic peptides corresponding to immunoglobulin J regions and to J regions predicted from gene sequence of the T-cell receptor beta chain. We found that antibodies produced against a synthetic 16-mer J beta sequence reacted with T-cell receptor chains and also with immunoglobulin light chains. The cross-reactivity was dependent upon the J signature sequence FG()GT(R or K)L where the presence of a positively charged lysyl or arginyl residue was essential for cross-reactivity. We were able to classify J region determinants into two distinct antigenic sets; one corresponding to JH and the other corresponding to J kappa, J lambda, J beta and J alpha. Although considerable homology occurs between JH and JL (or J beta) sequences, little cross-reactivity was observed between these two J subsets. Antibodies raised against polyclonal murine IgG immunoglobulins contained antibody subpopulations specifically reactive with either JH or J beta peptides. The serological data derived here using antipeptide antibodies are consistent with computer modeling studies that indicate that the conformations of T-cell receptor variable regions resemble those of classical immunoglobulins. Our data comparing cross-reactivities restricted to the J region indicate that the expression of the J region by intact T-cell receptor beta chains is probably more similar to that of light chains than it is to the corresponding region of heavy chains.

A role for human heavy chain binding protein in the developmental regulation of immunoglobin transport

Human EBV transformed lymphoblastoid cell lines and lymphomas representing various stages of B cell development were examined for heavy chain binding protein (BiP) expression and its association with immunoglobin (Ig) heavy chains. Human BiP was shown to migrate with an apparent mol. wt of 79,000 and to have a pI of approximately 5.5 in all the human cell lines examined. Both the mum and the mus heavy chains synthesized in a pre-B cell line (mu+, LC-) remained associated with BiP and were all found to be endo H sensitive, suggesting that this association occurred in the endoplasmic reticulum (ER). Surface Ig+ B cell lines produce membrane type heavy chains which are expressed on the cell surface and secretory type heavy chains which remain intracellular. The membrane type mu heavy chains produced by a surface Ig+ B cell line were not associated with BiP after assembling with light chains and processing in the Golgi. However, the secretory type mu heavy chains synthesized by these same cells did not combine efficiently with LC and a significant quantity remained associated with BiP and were not secreted suggesting that BiP is involved in the divergent transport of membrane and secretory mu heavy chains in surface Ig+ B cell lines. In Ig secreting plasmacytoid lines the heavy chains were only associated with BiP prior to assembling with LC. When LC assembly was inhibited, the association of heavy chains with BiP was prolonged and Ig secretion was blocked. Therefore, BiP was found to participate in the post-translational processing of mu heavy chains synthesized by human lymphoid cell lines representing all stages of B cell development. Further, heavy chains that remained associated with BiP were not transported to the cell surface or secreted while heavy chains that were only transiently associated with BiP chains were expressed on the cell surface or secreted.

Effects of concanavalin A, phytohemagglutinin, pokeweed mitogen, and lipopolysaccharide on the replication and immunoglobulin synthesis by canine peripheral blood lymphocytes in vitro

Canine peripheral blood lymphocytes (cPBLs) were used to investigate the mitogenic effects of Con A (concanavalin A), LPS (lipopolysaccharide), PHA (phytohemagglutinin), and PWM (pokeweed mitogen) in vitro by measuring tritium-labeled thymidine [( 3H]thymidine) incorporation and immunoglobulin (Ig) secretion. An ELISA specific for canine IgG and IgM showed that cPBLs secreted significantly more IgG than IgM in response to mitogen concentrations from 30,000 to 0.03 ng/10(5) cells. The optimal stimulating dose of mitogen for lymphocyte response measured by IgG secretion was over a much narrower range of concentration than was the [3H]thymidine incorporation measured response. At a concanavalin A dose where there was increased [3H]thymidine incorporation with a decrease in IgG secretion, it appeared that an active suppression of the IgG response was induced.

Follicular mantle zone cell subpopulations detected by monoclonal antibody SN3

A monoclonal antibody, SN3, has been prepared against a cell membrane fraction of the pre-B leukemic cell line NALM-1. By radioimmunoassay, SN3 reacted with four of four non-T/non-B, two of two pre-B and one of three leukemic B cell lines. The reagent was unreactive, however, with established leukemic T and myelomonocytic cell lines or normal B cell lines. On immunohistochemical assays on frozen sections of nine reactive lymph nodes and three spleens, SN3 showed a preferential binding to 50-95 per cent mantle zone (MZ) cells and 5-20 per cent interfollicular or red pulp B-lymphocytes. This was uninhibited by pre-incubation with heterologous anti-HLA-DR or anti-delta reagents. SN3 was unreactive with normal germinal centre (GC), epidermal or Langerhans cells but did react with less than 1 per cent thymic B-lymphocytes. In eight follicular small cleaved cell lymphomas tested SN3 exhibited three patterns of reactivity: peripheral follicular, combined peripheral and central follicular, and combined follicular and interfollicular. Three follicular lymphomas were essentially SN3-. In three diffuse small lymphocytic lymphomas, SN3 showed patchy areas of reactivity unassociated with proliferation centres. In four diffuse B-cell lymphomas (one mixed small and large cell, two large non-cleaved cell, and one small non-cleaved (Burkitt) cell), SN3 reactivity was uniformly distributed in the majority (60-90 per cent) of the cells. SN3 was unreactive with one diffuse B-large cell lymphoma, three nodal T-cell lymphomas and three cases of mycosis fungoides. The findings indicate that SN3 detects an antigen that is present in subpopulations of normal MZ cells, the antigen is also detected in GC cells undergoing lymphomatous transformation but is not readily detected in normal GC cells, and the antigen is also expressed in subpopulations of diffuse B- but not T-cell lymphomas.

Effect of passive administration of alloantiserum containing antibody against putative acceptor(s) for T cell-replacing factor (TRF) in the neonatal stage on development of B cell activity responsive to TRF

Previously, we showed that the antiserum raised in male (DBA/2Ha X BALB/c)F1(DCF1) mice (T cell-replacing factor [TRF]-low response animals) by immunizing them with activated B cells from BALB/c mice (TRF-high-responders) contained antibodies against putative TRF-acceptor site(s). We have now evaluated the hypothesis that neonatal treatment of mice with the above antiserum suppresses the development of B cells responsive to TRF. Male DCF1 mouse anti-BALB/c B-cell antiserum or normal DCF1 mouse serum as a control was injected into BALB/c mice within 24 hr after birth. In the antiserum-treated mice, no augmented primary immunoglobulin M (IgM) antibody responses to sheep red blood cells (SRBC) were observed under the conditions in which markedly augmented IgM anti-SRBC responses were induced in control BALB/c mice, suggesting that development of B cells reacting with male DCF1 mouse anti-BALB/c B-cell antiserum is suppressed by the neonatal treatment with the antiserum. Furthermore, the development of B cell activity responsible for helper factors derived from T cells, such as TRF, was markedly suppressed in the neonatally antiserum-treated mice, whereas activity of B cells capable of interacting directly with helper T cells through antigen-bridges was not significantly affected by the same treatment. Such suppression of the B cell activity could be induced only when the antiserum was administered within 48 hr after birth. Moreover, neonatal treatment of mice with the antiserum induced suppressed responsiveness of B cells to a T-independent type 2 antigen, TNP-Ficoll. Neither serum-borne suppressive serum components nor suppressor cells were detected by the system employed. These results support the hypothesis that TRF responsive B cells constitute a subpopulation distinct from the other B cells capable of cooperating with helper T cells via cognate interaction.

Monoclonal idiotope vaccine against Streptococcus pneumoniae infection

A monoclonal anti-idiotope antibody coupled to a carrier protein was used to immunize BALB/c mice against a lethal Streptococcus pneumoniae infection. Vaccinated mice developed a high titer of antibody to phosphorylcholine, which is known to protect against infection with Streptococcus pneumoniae. Measurement of the median lethal dose of the bacteria indicated that anti-idiotope immunization significantly increased the resistance of BALB/c mice to the bacterial challenge. Antibody to an idiotope can thus be used as an antigen substitute for the induction of protective immunity.

Changes in J chain and mu chain RNA expression as a function of B cell differentiation

The time course of differentiative events in the pentamer IgM response was examined by following the expression of J chain and mu chain RNA and their protein products in mitogen-stimulated lymphocytes. The analyses showed that the shift to mus RNA synthesis begins shortly after stimulation and precedes proliferation of the cells and any increase in mu RNA levels. In contrast, expression of J chain RNA and the amplification of J chain and mus message are late events that coincide with a phase of rapid proliferation and with the secretion of pentamer IgM antibody. The kinetics of J and mu chain RNA expression observed in normal lymphocytes were supported by analyses of lymphoid cell lines. B lymphomas were found to display the RNA pattern characteristic of early-activated lymphocytes, i.e., a partial shift to mus RNA production and no J chain RNA, whereas IgM-secreting lines resembled late-activated lymphocytes in their expression of high levels of both mus and J chain mRNA. Moreover, the kinetics of J and mus chain RNA expression correlates with the sequential action of B cell lymphokines in the induction of the pentamer IgM response. This correlation suggests that the successive differentiative changes are triggered by successive membrane stimuli.

Depletion of murine anti-azobenzenearsonate plaque-forming cells by derivatized polyacrylamide beads

The depletion of secondary p-azobenzenearsonate plaque-forming cells (ABA-PFC) by affinity columns substituted with ABA was dependent on the primary dose, times elapsed after priming, and the nature of the side-arm on the columns. Thus, higher priming doses of ABA coupled to keyhole limpet haemocyanin (50-500 micrograms of ABA-KLH in complete Freund's adjuvant (CFA] favoured depletion of ABA-PFC by ABA coupled to a 6- aminocaproyltyrosine side-arm (SAC-TYR-ABA beads), whereas ABA-PFC from mice primed with 1 microgram of ABA-KLH in CFA were never depleted; this latter population were only depleted by ABA coupled to a histamine side-arm (HIST-ABA beads) 7 months after priming. These data are consistent with the notion that two specificities, HIST-ABA and TYR-ABA, appear to emerge independently, lower priming doses inducing the preferential appearance of the HIST-ABA specificity.

Binding of antigen in the absence of histocompatibility proteins by arsonate-reactive T-cell clones

Inducer T-cell clones reactive to the p-azobenzenearsonate (arsonate) hapten possess binding sites for radioactive arsanylated proteins, which are not present on clones with other antigen specificities. Binding occurred in the absence of histocompatibility proteins. Binding was specific for the p-azobenzenearsonate hapten, since unconjugated proteins and proteins conjugated to the nonactivating o-azobenzenearsonate hapten neither bound to the clones nor competed binding of radioactive antigen. One of the clones was studied in more detail, using a panel of structural analogs of arsonate conjugated to the carrier protein ovalbumin. All conjugates that activated the clone in the presence of antigen-presenting cells also competed binding of radioactive antigen in the absence of antigen-presenting cells. Nonactivating conjugates did not compete binding. Based on evidence in this and the succeeding paper (Rao et al., accompanying paper), we suggest that these arsonate-binding sites may include the physiological antigen receptors of arsonate-reactive T-cell clones.

A novel method for radiolabeling antigen-binding receptors of lymphocytes

Antigen-binding receptor (ABR) molecules have been selectively radiolabeled and isolated from immunized chicken spleen cells. The specific radiolabeling of the receptors has been accomplished by utilizing a novel technique employing lactoperoxidase (LPO) covalently linked to antigen (Ag) for which human gammaglobulin was used. The cell surface ABRs were first bound to the Ag-LPO conjugates through specific recognition sites on the Ag portion of the conjugates. The bound LPO portions were then allowed to catalyze the radioiodination of the ABRs. After radiolabeling, cells were solubilized with detergents. ABRs still bound to Ag-LPO conjugates were directly isolated from the lysates via immunoaffinity chromatography utilizing an immunoaffinity reagent directed toward the antigen portion of the ABR-Ag-LPO complex. The radioactive materials isolated in this way were then analyzed via SDS-PAGE under reducing conditions. It appears that as expected, most of the specifically-labeled and isolated materials were immunoglobulin (Ig). Both the membrane-bound form of the heavy chain (mol. wt 77 K) as well as the secreted form (mol. wt 67 K) were detected, along with the light chain (mol. wt 25 K). An additional polypeptide of mol. wt 55 K was also selectively labeled and isolated along with the Ig. This may be a molecule closely associated with the membrane immunoglobulin on B-cell surface.

Affinity-purified antigen-specific products produced by T cells share epitopes recognized by heterologous antisera raised against several different antigen-specific products from T cells

Heterologous antisera to murine or rat T-cell antigen-binding molecules (T-ABM) were raised in rabbits or sheep. The T-ABM used for immunization were purified by affinity for antigen and did not bear known immunoglobulin isotypes. T-ABM and anti-T-ABM were raised in three separate laboratories. Antisera to T-ABM were exchanged and tested for binding to T-ABM in three separate laboratories. Thus antisera to at least three distinct T-ABM were tested directly for binding to T-ABM or by adsorption of biological activity. Rabbit antisera to murine trinitrophenol (TNP)-specific T-ABM or rat AgB-specific T-ABM bound both murine or rat T-ABM, indicating evolutionary conservation of T-ABM. Similar results were found with sheep antisera to murine T-ABM. In addition, all heterologous anti-T-ABM antisera used bound murine T-ABM specific for TNP, 4-hydroxy-3-nitrophenyl acetate (NP), SRBC, or T-cell membrane proteins with similar structure. Thus, there is a commonality of antigenic determinants between various T-ABM and T-cell membrane homologues which may be T-cell surface receptors for foreign antigen.

LPS-nonresponsive variants of mouse B cell lymphoma, 70Z/3: isolation and characterization

We have used a genetic approach to study the differentiation of B lymphocytes. The cultured murine cell line 70Z/3 resembles pre-B cells in containing the heavy chain of the immunoglobulin IgM, mu, as an internal protein in the absence of light chain, L. However, overnight incubation with the B cell mitogen lipopolysaccharide (LPS) induces the cells to mature to a B lymphocyte-like state by the induction of L chain synthesis and the appearance of IgM on the cell surface. We have used immunoselection against surface-bound IgM to isolate LPS uninducible variants of 70Z/3. These fall into two complementation groups, LPS A and LPS B. LPS A variants predominated and were found at a frequency of 1/1200. These cells were completely unresponsive to LPS. LPS B was represented by a single variant in which a subset of cells was induced to display wild-type levels of membrane-bound IgM, and the proportion of induced cells increased with prolonged incubation with LPS. We detected no structural defects in either variant group, but LPS B may represent a defect in the decision to differentiate in response to LPS.

ACA-1, a new differentiation antigen of activated lymphoid cells

Rabbits were immunized with murine CBA T lymphocytes activated with C57BL/6 antigens (Tact). The immune rabbit sera were adsorbed with murine erythrocytes, serum, liver cells, and unstimulated T and B lymphocytes. Upon absorption, the antisera (ATactS) were not cytotoxic for unactivated thymus, lymph node, and spleen cells of different mouse strains in the cytotoxicity assay. ATactS did not inhibit the immune response of lymphocytes from unimmunized animals to SRBC or their proliferation in mixed lymphocyte culture. At the same time ATactS lysed 67% of actively proliferating T-lymphoma EL-4 cells, 31-56% of the T lymphocytes stimulated with allogeneic cells, and 53-56% of Con A- or LPS-stimulated splenocytes. ATactS also inhibited 90-100% of antigen-activated B cells, i.e., plaque-forming cells (PFC) producing 19 S and 7 S antibodies to serologically noncrossreacting antigens, such as sheep, rabbit, and rat RBC. It also decreased the intensity of the secondary immune response to SRBC. The effect of ATactS did not depend on the H-2 or Ala-I phenotype of target cells. Our experiments showed that ATactS activity fell after absorption with activated, but not quiescent lymphoid cells. These results suggest the presence of a special antigenic marker on activated murine T and B cells which differs from the generally recognized cell surface antigens, such as H-2, Ig, Ala-I, idiotype, Thy-I, MBLA, MTLA, Lyt-1,2,3, and others. It has been designated Aca-I (activated cell antigen).

A human B lymphocyte antigen (P-76) shared by B-cell chronic lymphocytic leukemia cells and hairy cell leukemia cells

A membrane antigen with an apparent specificity to B lymphocytes was detected with immunochemical techniques and its properties were analyzed. Anti-B-CLL serum was raised in a rabbit by immunization with B-cell chronic lymphocytic leukemia (B-CLL) cells. This anti-B-CLL serum was absorbed with erythrocytes, liver homogenate and insolubilized immunoglobulins. After further absorption with T-CLL cells, chronic myelocytic leukemia (CML) cells and acute myelocytic leukemia (AML) cells, the anti-B-CLL serum still reacted with peripheral blood B lymphocytes, B-CLL cells and hairy cell leukemia (HCL) cells. In contrast, no reactivity was seen with peripheral blood T lymphocyte or monocytes, or leukemia cells of non-B cell origin. An immunoprecipitation of radiolabeled cell surface proteins was attempted using the anti-B-CLL serum in the presence of Staphylococcus Aureus Cowan 1 (SaCl), and the precipitates were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). A membrane antigen with an apparent molecular weight of 76,000 daltons (P-76) was immunoprecipitated with the anti-B-CLL serum from the lysates of normal B lymphocyte, B-CLL cells and HCL cells. The antigen (P-76) is not composed of disulfide-linked subunits and has no structural relationship with HLA-DR (Ia-like) antigens or other known antigens. These results suggest that this antigen is B-lymphocyte specific, and favour the B-lymphocyte nature of HCL cells.

Anti-idiotype antibody-dependent cell-mediated cytotoxicity (ADCC) against idiotype-bearing cells

The present report demonstrates that cells expressing idiotypic determinants on their surfaces can be specifically destroyed by anti-idiotypic antibodies acting as inducers of antibody-dependent cell-mediated cytotoxicity. Lysis of surface-idiotype-positive hybridoma cells was effected by mouse spleen cells, mouse peritoneal cells, or human blood mononuclear cells, in the presence of anti-idiotypic antibodies. In order for lysis to occur, the simultaneous presence of Fc receptor-bearing cytotoxic cells and anti-idiotypic antibodies was required. Specificity of lysis was conferred by the anti-idiotypic antibody. Hybridoma cells expressing a different idiotype could not be lysed. Anti-idiotypic antibody-dependent cell-mediated cytotoxicity against 51Cr-labeled cells expressing a particular idiotype could be induced by the specific anti-idiotypic antibodies and inhibited by unlabeled idiotype-positive cells or by idiotype in a soluble form. Cytotoxicity could not be inhibited by the presence of bystander cells or monoclonal antibodies expressing a different idiotype. It is proposed that ADCC lysis of idiotype-positive cells has important implications for understanding the regulation of immune responses by an idiotype-anti-idiotype network. This cytolytic pathway provides an extremely specific and effective mode of control of idiotype-positive cells by anti-idiotype antibody. Previous observations that an intact Fc fragment was necessary for anti-idiotype antibodies to exert suppressive effects in vivo further support this hypothesis.

Biochemical characterization of mIgM- variants of the murine B-cell lymphoma, WEHI 279.1

The membrane immunoglobulin M (mIgM) of a B lymphocyte serves as a receptor for its cognate antigen. Our aim is to elucidate the structure and function of this membrane-bound receptor. The first step is to determine the requirements for proper membrane placement of IgM. We have used mIgM-positive B lymphocyte tumors from which we isolated mIgM negative variants by immunoselection. We report here the initial characterization of mIgM- variants isolated by repeated cycles of selection of the murine B lymphoma, WEHI 279.1, with goat anti-mouse immunoglobulin (G alpha MIg) and complement. These particular variants were chosen from a pool of more than 150 variants originally isolated because they resulted from several selection schemes and clearly had different origins. By analysis of their proteins, we have found three major phenotypes that do not produce mIgM: reduced microns, microseconds and L chain levels within cells, loss of microns and microseconds but retention of L chain synthesis, and loss of microns but retention of reduced amounts of microseconds and L chain. The defects underlying these phenotypes produce complex changes in the synthesis, turnover, and secretion of the mu or L chains involved. We performed experiments comparing the effects of the glycosylation inhibitor tunicamycin on variants with reduced mu and L levels with its effects on variants with L but no mu chains. These experiments suggested that mu and L chain synthesis are controlled coordinately at the level of protein synthesis. We have not yet isolated any variants lacking L chain synthesis or any appearing to have gross structural defects in the micron protein. This analysis is the first phase of the detailed characterization of the requirements for proper synthesis, processing, tetramer formation, and membrane display of mIgM on B lymphoma tumors in mice.

Determination of dissociation constants and ligand specificity of detergent solubilized surface membrane immunoglobulin A from MOPC-315

Surface membrane immunoglobulin from MOPC-315 plasmacytoma cells (smM315) was isolated by nonionic detergent lysis of radioiodinated cells and affinity chromatography on Dnp-aminohexyl-Sepharose 4B. Verification of the solubilized molecule as an integral membrane protein, distinct from secreted MOPC-315 IgA (M315) was accomplished by NaDodSO4-PAGE, charge-shift electrophoresis and molecular sieve gel filtration with NP-40 and deoxycholate. smM315 was compared to reduced and alkylated monomeric secreted immunoglobulins from MOPC-315, MOPC-460, and XRPC-25 by quantitative affinity chromatography (QAC) using two differently substituted Dnp-aminohexyl-Sepharose 4B resins. Unique patterns of cross-reactivity of all secreted myeloma proteins were independently established with a competitive hapten inhibition assay using 125I-Dnp26BSA as the precipitating probe. After derivation with dinitrobenzylsulfonate, Dnp-aminohexyl-Sepharose 4B was modified with succinic anhydride which, with the inclusion of 0.03% Doc in a PBS and 0.1% NP-40 buffer, prevented nonhapten specific protein-matrix interactions during QAC. Dissociation constants determined by QAC for three ligands, (dinitrophenyl-glycine, trinitrophenyl-amino-caproate and tetramethylrhodamine) were essentially the same for smM315 and M315. Both of the other nitrophenyl binding IgA myelomas had distinct and significant differences in dissociation constants. Thus, for a differentiated antibody secreting cell which has undergone a heavy chain class switch, such as MOPC-315, the cell surface immunoglobulin has an identical ligand binding active-site as the secreted immunoglobulin.

Selection of membrane IgM- variants from a mIgM+ murine B lymphoma cell: problems and solutions

We have used antibody-mediated complement killing to isolate membrane IgM-negative (mIgM-) variants from the mIgM+ murine B cell lymphoma, WEHI 279.1. This procedure has been used previously to select variants which lack expression of other cell-surface antigens on lymphoid cells. In those experiments, multiple rounds of selection have often been required for selection of the negative variants. We found that many cycles of selection produced very few variants and that those isolated had reduced, but still measurable, levels of mIgM. We were able to select large numbers of stable mIgM- variants by subjecting the populations with reduced levels of mIgM to two rounds of immunoselection within one cell cycle. These variants are stable and exhibit a variety of defects which are all expressed as a failure to display IgM on their external surface. Analysis of these variant clones at the biochemical level will begin to define the requirements for proper display of mIgM on the cell membrane of B lymphoma cells.

Mouse alloantigen system Ly-m22 predominantly expressed on T lymphocytes and controlled by a gene linked to M1s region on chromosome 1

Spleen cells from a DBA/2 mouse immunized with RL male 1 tumor cells, a radiation induced BALB/c T-cell leukemia, were hybridized with the nonsecretor myeloma line NS.1. Four established hybrid cell lines continuously secreted antibodies that recognized a new alloantigenic specificity, tentatively called Ly-m22. This antigen is detectable on nearly 60% of lymph node cells, and 30% of spleen cells by direct cytotoxicity assay, but did not lyse significant number of cells of thymus and bone marrow. By absorption test, these lymphoid organs, i.e., lymph node, spleen, thymus, and bone marrow, were shown to express Ly-m22 determinant. The newly found antigen is expressed predominantly on T-cells. Analysis of BXD and SWXL recombinant inbred strains revealed close linkage between Ly-m22 and Ltw-4 loci on chromosome 1. The estimated recombination frequency is 0.027 +/- 0.081.

Detection of antigen specific rosette formation with the FACS

Donors previously sensitized to conventional antigens PPD and KLH were evaluated for their antigen binding responses, utilizing a rosette forming technique with antigen-conjugated autologous erythrocytes. Reactivity is directly correlated with prior sensitization. Furthermore, antigen specificity is suggested by inhibition of rosette formation by prior incubation with the relevant antigen. The frequency of RFCs detected cytofluorometrically was compared with conventional fluorescent microscopy determinations. RFCs detected in this manner were identified as antibody armed monocytes by cell depletion and histochemical studies. The usefulness of the rosette forming technique for the routine evaluation of donor immunity is discussed.