Isolation and characterizaiton of murine cell surface components. I. Purification of milligram quantities of Thy-1.1.

The Thy-l.1 molecule was isolated from the BW5147 murine lymphoblastoid cell line. The initial step in purification was the preparation of a crude plasma membrane fraction followed by acetone precipitation. The acetone pellet was solubilized using deoxycholate (DOC) and Thy-1.1 was purified by use of a Lens culinaris lectin affinity column and an AcA-34 gel filtration column. The purified glycoprotein with Thy-1.1 activity had a mol wt of approximately 25,000 daltons. The isolation of this molecule was effected by detecting Thy-I activity utilizing rabbit anti- mouse brain serum tested on rat thymocytes. Congenic anti-Thy-l.1 serum was ineffective in detecting Thy-l.1 after DOC solubilization. An antiserum prepared in rabbits to the purified Thy-1.1 was found to be cytotoxic to mouse and rat thymocytes. The cytotoxic activity of this antisera could be completely absorbed with AKR/Jax brain and thymus but was not absorbed by liver. In addition, AKR/Jax thymocytes totally absorbed all cytotoxic activity of the rabbit anti-purified Thy-1 serum for BW5147 cells suggesting that the cell line shares identical specificities with normal thymocytes. The purified Thy-1.1 molecule was able to totally absorb the cytotoxic activity of mouse congenic anti-Thy-1. These studies serve as a model for the isolation of other murine lymphoid cell surface components in quantities for detailed structural and functional analysis.

Qa-2, H-2K, and H-2D alloantigens evolved from a common ancestral gene.

The Tla region located on the murine 17th chromosome controls several serologically defined cell surface antigens. These antigens, referred to as Qa-1-5 and TL, are expressed on a variety of hematopoeitic cell populations. In the present studies we have immunoprecipitated isotopically labeled Qa-2 and H-2 molecules from mitogen-stimulated B6 spleen cells. Sequential immunoprecipitation experiments have shown that the determinants recognized by alpha Qa-2, alpha H-2Kb, and alpha H-2Db alloantisera reside on separate molecular species. Comparative mapping of the arginine-labeled tryptic peptides from Qa-2, H-2Kb, and H-2Db molecules indicate that Qa-2 is structurally distinct but that there is considerable structural homology; 21-43% of the Qa-2 peptides co-chromatograph with peptides derived from H-2Db and H-2Kb, respectively. Similar levels of homology are observed when Qa-2 is compared with H-2Kk or H-2Dd. The results show that the Qa-2 alloantigen is encoded by a locus separate from the loci encoding H-2K or H-2D alloantigens, but that the Qa-2, H-2K, and H-2D alloantigens are sufficiently related at the primary structural level to indicate that they evolved from a common primordial gene.

In vitro analysis of allogeneic lymphocyte interaction. I. Characterization and cellular origin of an Ia-positive helper factor-allogeneic effect factor.

A soluble allogeneic effect factor (AEF) was produced by using H-2 congenic mouse strains and a serum.free cell culture medium. An AEF derived from untreated activated responder cells and irradiated stimulator cells provided helper cell function in a primary and secondary antibody response for both T-cell-depleted responder B cells and stimulator B cells. This interaction may be determined by genes situated in the I-A and I-B regions: additional K-region control was not excluded. Ia antigens, but neither H-2 nor Ig determinants are molecular constituents of AEF. The active components of this AEF consist, in part, of Ia antigens derived from both the activated responder cell population and irradiated stimulator cell population. An AEF derived from Ia negative responder cells and irradiated T-cell- depleted stimulator cells helps a secondary antibody response of T-cell- depleted stimulator B cells but not responder B cells. This genetically restricted AEF contains Ia antigens determined by the stimulator haplotype but not the responder haplotype. The priming antigen, DNP- keyhole limpet hemocyanin, is not a component of restricted AEF. The data suggest that restricted AEF may be a product of a stimulator B cell and/or macrophage. They support the hypothesis that the recognition by allogeneic T cells of Ia antigens on B cells activates the B cell to IgG antibody production.

Isolation and immunologic characterization of a human. B-lymphocyte-specific, cell surface antigen.

In addition to HL-A antigens, another cell surface protein complex has been obtained from membranes of the human B-lymphoblast cell line IM-1. This complex which was solubilized with papain, consisted of polypeptides of 23,000 and 30,000 daltons (p23, 30). Rabbit antisera to this material precipitated from [35S]methionine-labeled detergent-solubilized cells, three proteins of 39,000, 34,000, and 29,000 daltons. These antisera were specifically cytotoxic for B lymphocytes of peripheral blood, for B-lymphoblast cell lines, and for EAC rosette receptor-positive surface Ig-negative (Null) lymphocytes. The p23,30 complex was not present on T lymphocytes, EAC rosette receptor-negative Null lymphocytes, or platelets. In addition, the p23,30 complex from several cell lines inhibited alloantisera from multiparous Amish women which had been shown to recognize non-HL-A, B-lymphocyte antigens. Some other properties of the anti-p23,30 sera antisera were described.

A mouse B-cell alloantigen determined by gene(s) linked to the major histocompatibility complex.

Antibodies cytotoxic for only a subpopulation of C57Bl/10 lymph node and spleen cells were detected when rat antiserum against B10.D2 was exhaustively absorbed with B10.A lymphocytes. Antibodies of similar specificity were also detected in B10.A anti-B10.D2 and in B10.A anti-C57Bl/10 alloantisera. Reactions with recombinant strains of mice indicate that the cell-surface antigen(s) responsible for this specificity is determined by gene(s) in or to the left of the Ir-1 region of the major histocompatibility complex. A variety of criteria implicate B cells as the subpopulation of lymphocytes bearing this antigen. In view of these data and the recent report by others of a T-cell alloantigen determined by gene(s) in the major histocompatibility complex, it seems possible that there may be a variety of H-2-linked alloantigens expressed preferentially on subclasses of lymphocytes.

Isolation and immunochemical characterization of rabbit 7S anti-IgG with restricted heterogeneity.

7S anti-IgGs were isolated from four rabbit antistreptococcal antisera by the use of immunoabsorbent columns. The isolated proteins were of restricted molecular heterogeneity; they formed a monodisperse band on microzone electrophoresis and had a limited number of light chain bands when analyzed on urea polyacrylamide gel. The binding site of the 7S anti-IgGs was detected in the F(ab')(2) portion of the molecule. The binding site has antibody specificity for the Fc portion of IgG. For one 7S anti-IgG the combining site on the Fc portion could further be defined. A pepsin fragment of Fc, described as Pep-III', was a potent inhibitor of the coprecipitation of 7S anti-IgG with antigen-antibody complexes. An idiotypic cross-reaction was detected between the 7S and 19S anti-IgGs isolated from the same rabbit with anti-idiotype sera prepared in guinea pigs. This idiotypic specificity was not detected in the 7S anti-IgGs of 20 other rabbits.

A single T cell receptor recognizes structurally distinct MHC/peptide complexes with high specificity.

The 2C T cell is a CD8+, alloreactive T cell, which recognizes cells bearing Ld and Kbm3 class I major histocompatability complex molecules. Here, we characterize an allopeptide, designated dEV-8, that is a ligand in the Kbm3 molecule for the 2C TCR but is not a ligand in the Ld molecule. By biochemical and immunological properties, dEV-8 is distinct from P2Ca, the Ld allopeptide that is also recognized by the 2C TCR. Using the deduced amino acid sequence of dEV-8, we isolate a candidate endogenous source of the peptide. The endogenous protein, MLRQ, contains a peptide sequence identical to dEV-8. This degenerate recognition of two distinct peptide/MHC complexes by a single TCR has important implications for understanding allorecognition.

Some biochemical properties of thymus leukemia antigens solubilized from cell membranes by papain digestion.

Thymus leukemia (TL) alloantigenic activity was solubilized by papain proteolytic digestion from intact RADA1 tumor cells. If the cells were labeled with amino acids and fucose, the TL alloantigen could be isolated as a doubly labeled glycoprotein fragment by indirect precipitation from the papain digest. This TL glycoprotein fragment was approximately the same mol wt as the papain-digested H-2.4 alloantigen fragment as judged by chromatography on Sephadex G-150 in sodium dodecyl sulfate. The carbohydrate chain of the TL glycoprotein obtained by exhaustive pronase digestion behaved as a glycopeptide of approximately 4,500 mol wt, as compared with the glycopeptide of the H-2.4 alloantigen that had a mol wt of about 3,500. Thus, the TL alloantigen can be solubilized by papain digestion as a glycoprotein fragment similar in mol wt to the H-2 alloantigen glycoprotein fragment. The carbohydrate chain of the TL glycoprotein is larger than the H-2 carbohydrate chain.

Isoantigenic variants: isolation from human diploid cells in culture.

Variant human fibroblast substrains, resistant to a cytotoxic human isoantiserum, were isolated from sensitive strains by repeated exposure to isoantiserum and rabbit complement. The resistant phenotype was stable, apparently occurred at low frequency, and was associated with loss of surface isoantigens.

Molecular heterogeneity of human lymphoid (HL-A) alloantigens.

Soluble preparations of HL-A alloantigens were separated by gel filtration into components having either the "LA" series or the "4" series of alloantigenic determinants. This separation may indicate that several different structural cistrons within the HL-A (locus) control the expression of these two series of determinants. The alternative possibility, in which one structural cistron with multiple mutational sites controls the synthesis of a single molecule cannot be excluded.

Immunocontraceptive target repertoire defined by systematic identification of sperm membrane alloantigens in a single species.

Sperm competence in animal fertilization requires the collective activities of numerous sperm-specific proteins that are typically alloimmunogenic in females. Consequently, sperm membrane alloantigens are potential targets for contraceptives that act by blocking the proteins' functions in gamete interactions. Here we used a targeted proteomics approach to identify the major alloantigens in swine sperm membranes and lipid rafts, and thereby systematically defined the repertoire of these sperm-specific proteins in a single species. Gilts with high alloantibody reactivity to proteins in sperm membranes or lipid rafts produced fewer offspring (73% decrease) than adjuvant-only or nonimmune control animals. Alloantisera recognized more than 20 potentially unique sperm membrane proteins and five sperm lipid raft proteins resolved on two-dimensional immunoblots with or without prior enrichment by anion exchange chromatography. Dominant sperm membrane alloantigens identified by mass spectrometry included the ADAMs fertilin α, fertilin ß, and cyritestin. Less abundant alloantigens included ATP synthase F1 ß subunit, myo-inositol monophosphatase-1, and zymogen granule membrane glycoprotein-2. Immunodominant sperm lipid raft alloantigens included SAMP14, lymphocyte antigen 6K, and the epididymal sperm protein E12. Of the fifteen unique membrane alloantigens identified, eleven were known sperm-specific proteins with uncertain functions in fertilization, and four were not previously suspected to exist as sperm-specific isoforms. De novo sequences of tryptic peptides from sperm membrane alloantigen "M6" displayed no evident homology to known proteins, so is a newly discovered sperm-specific gene product in swine. We conclude that alloimmunizing gilts with sperm membranes or lipid rafts evokes formation of antibodies to a relatively small number of dominant alloantigens that include known and novel sperm-specific proteins with possible functions in fertilization and potential utility as targets for immunocontraception.

The human platelet alloantigens, PlA1 and PlA2, are associated with a leucine33/proline33 amino acid polymorphism in membrane glycoprotein IIIa, and are distinguishable by DNA typing.

The human platelet alloantigens, PlA1 and PlA2, comprise a diallelic antigen system located on a component of the platelet fibrinogen receptor, membrane glycoprotein (GP) IIIa. Of the known platelet alloantigens, PlA1, which is carried by 98% of the caucasian population, appears to be the alloantigen that most often provokes neonatal alloimmune thrombocytopenic purpura and posttransfusion purpura. The structural features of the GPIIIa molecule responsible for its antigenicity are as yet unknown. Using the polymerase chain reaction (PcR), we amplified the NH2-terminal region of platelet GPIIIa mRNA derived from PlA1 and PlA2 homozygous individuals. Nucleotide sequence analysis of selected amplified cDNA products revealed a C in equilibrium T polymorphism at base 196 that created a unique Nci I restriction enzyme cleavage site in the PlA2, but not the PlA1 form of GPIIIa cDNA. Subsequent restriction enzyme analysis of cDNAs generated by PcR from 10 PlA1/A1, 5 PlA2/A2, and 3 PlA1/A2 individuals showed that Nci I digestion permitted clear discrimination between the PlA1 and PlA2 alleles of GPIIIa. All PlA2/A2 individuals studied contain a C at base 196, whereas PlA1 homozygotes have a T at this position. This single base change results in a leucine/proline polymorphism at amino acid 33 from the NH2-terminus, and is likely to impart significant differences in the secondary structures of these two allelic forms of the GPIIIa molecule. The ability to perform DNA-typing analysis for PlA phenotype may have a number of useful clinical applications, including fetal testing and determination of the phenotype of severely thrombocytopenic individuals.

Identification of immunogenic MHC class II Tyrosinase-derived peptides using HLA-DR1 and HLA-DR4 transgenic mice.

The immunogenicity of "novel" MART-1 and Tyrosinase class-II peptides was assessed in transgenic mice. Tyrosinase(141-161) peptide was found to be immunogenic and endogenously processed in the HLA-DRbeta1*0101 and HLA-DRbeta1*0401 transgenic mice with peptide specific production of IFNgamma or IL-5 respectively. The MART-1(29-43) peptide was only found immunogenic in HLA-DRbeta1*0101 mice.

Identification of Leb antigens in meconium of a phenotypically a Le(a+ b-) non-secretor individual.

Blood group active fucolipids of human meconium have been shown to correlate to the ABH and Lewis blood groups and to the secretor status of the corresponding children. Using a monoclonal anti-Leb antibody and an antibody to chromatogram binding assay the presence of Leb antigens in meconium of a phenotypically A Le(a+ b-) non-secretor individual is here demonstrated. Phenotype was determined on cord blood and saliva obtained 2 years after birth.

Tetrahymena gene encodes a protein that is homologous with the liver-specific F-antigen and associated with membranes of the Golgi apparatus and transport vesicles.

The F-antigen is a prominent liver protein which has been extensively used in studies on natural and induced immunological tolerance. However, its intracellular localization and biological function have remained elusive. It has generally been assumed that the F-antigen is confined phylogenetically to vertebrates. Now we have cloned and characterized a gene from the ciliated protozoan Tetrahymena thermophila encoding a protein which clearly is homologous with the rat F-antigen. The coding region of the Tetrahymena F-antigen (TF-ag) gene specifies a 46,051 M(r) protein and is interrupted by three introns. In accordance with the predicted molecular mass of the TF-ag protein, antibodies raised against a cro-lacZ'-TF-ag fusion protein specifically recognized a 45,000 M(r) protein in Western blots of total T. thermophila protein. Immunoelectron microscopy demonstrated that the TF-ag is associated with membranes of the Golgi apparatus and transport vesicles pointing to a role of TF-ag in membrane trafficking. Transcription of the TF-ag gene, as determined by run-on analyses, was only detectable in growing cells, and following transfer to starvation condition pre-existing TF-ag mRNA was rapidly degraded. The abundance of the TF-ag protein, however, declined only moderately during prolonged periods of starvation demonstrating that extensive release of the TF-ag did not take place. In combination these results suggest that the TF-ag protein is a recycled constituent of the intracellular membrane network in T. thermophila.

Single-step immunosorbent preparation of F-protein from mouse liver with conservation of the allo-antigenic site, and determination of concentration in liver and serum.

A single-step immunopurification procedure is described for murine protein F, in which the T-cell-defined allo-antigenic site on the protein is fully conserved. The procedure is based on the use of a newly developed monoclonal antibody. The protein is isolated as a 42,500 mol. wt (F.1) and a 43,000 mol. wt (F.2) monomer. The content in liver, as estimated by radioimmune inhibition assay, is 0.083% and the yield is approximately one third. An assay of immunogenic activity in adoptive transfer, which detects the T-cell-defined site, provides a similar estimate of content in liver. The adoptive transfer assay yields concns of F-protein in serum of young mice of 0.5-1.2 X 10(-9)M, the lowest concn of protein known to induce complete immunological tolerance.

Occurrence of platelet basic protein, a precursor of low affinity platelet factor 4 and beta-thromboglobulin, in human platelets and megakaryocytes.

beta-thromboglobulin antigen, a platelet-specific secreted protein, occurs in three forms: platelet basic protein, low affinity platelet factor 4, and beta-thromboglobulin. The combined level of beta-thromboglobulin antigen in megakaryocytes, measured by radioimmunoassay, was 13 +/- 7 micrograms/10(6) cells (SD, n = 6). The relative proportions of the three forms of beta-thromboglobulin antigen present within platelets and megakaryocytes were determined in cells lysed with trichloroacetic acid to minimize artifactual proteolysis. Samples were analyzed by isoelectric focusing in polyacrylamide gel with quantitative immunological detection on a nitrocellulose transfer of the gel. In platelets, the major species found was low affinity platelet factor 4 with precursor platelet basic protein as only 25% +/- 11% (SD, n = 16) of total beta-thromboglobulin antigen. In megakaryocytes partially purified both from normal bone marrow aspirates and from whole marrow specimens obtained after surgery, platelet basic protein was a higher proportion of beta-thromboglobulin antigen (49% +/- 13% SD, n = 11) than was the case in platelets. beta-thromboglobulin itself was never detected under the conditions of cell lysis used. Our results suggest that platelet basic protein is synthesized in megakaryocytes and that its cleavage is associated with an earlier stage of cell development than simply maturation to platelets. Further support for the precursor status of platelet basic protein was found in the expression of predominantly this antigenic form in a human erythroleukemia cell line.

Exposure of cryptantigens on red blood cell membranes in patients with acquired immune deficiency syndrome or AIDS-related complex.

Patients with acquired immune deficiency syndrome (AIDS) or AIDS-related complex (ARC) are subject to recurrent and severe infections due to organisms known to cause red blood cell membrane modifications. These red cell modifications include the exposure of novel carbohydrate cryptantigens that can react with naturally occurring antibodies and potentially result in hemolysis. We examined the frequency of cryptantigen exposure on the surface of red cells from AIDS/ARC patients. Blood samples from 108 patients with AIDS/ARC and from 65 non-AIDS/ARC patients were tested for most common forms of cryptantigens. The lectin Arachis hypogaea agglutinated red cells from 7% (8/108) of the AIDS/ARC patients and 3% (2/65) of non-AIDS/ARC patients, indicating the presence of T, Tk, or Th cryptantigen exposure. One sample from an AIDS patient with E. coli sepsis had T activation with polyagglutinable red cells. None of the samples showed evidence of exposed Tn or acquired B antigens. These results show that red cell cryptantigen exposure does occur in AIDS patients with a prevalence similar to that previously reported in patients with sepsis or malignancy. For this reason, and because polyagglutination has been associated with in vivo hemolysis, cryptantigen exposure should be considered in the differential diagnosis in AIDS patients with suspected immune hemolysis; it can be tested for by performing a minor crossmatch with ABO compatible serum.

Bulk immunopurification and development of a radioimmunoassay for human and murine F liver protein.

By taking advantage of the cross-reaction for human F liver protein (F antigen) of a monoclonal antibody raised to mouse F antigen, human F antigen has been immunopurified in bulk. The molecular weight is 44 000. Using this material as a standard, affinity-purified polyclonal anti-F antibody on a solid phase and radiolabelled monoclonal anti-F antibody to detect bound protein, a capture immunoradiometric assay capable of detecting down to 1 ng X ml-1 of F antigen has been developed. Using this assay, the average level of F antigen in normal mouse serum (CBA strain) is 16 ng X ml-1 (360 pM) and in human serum 10 ng X ml-1 (250 pM).

Homozygous protein C deficiency: observations on the nature of the molecular abnormality and the effectiveness of warfarin therapy.

An infant with severe homozygous protein C deficiency was brought to medical attention because of purpura fulminans and severe bilateral vitreous hemorrhages in the neonatal period. Infusions of fresh frozen plasma were given for 8 months. On two occasions, attempts to decrease the frequency of fresh frozen plasma infusions to less than twice a day led to episodes of microangiopathic hemolysis, fibrinolysis, and acute renal failure. Infarction of skin and subcutaneous tissues did not recur. Both episodes were controlled after reinstitution of fresh frozen plasma. Complications of therapy with fresh frozen plasma included hyperproteinemia and hypertension. Warfarin therapy was instituted when the baby was 8 months of age, followed by a gradual withdrawal of fresh frozen plasma therapy. The dose of warfarin required to maintain the prothrombin time in a range of 1.8 to 2.2 times normal varied considerably during short periods, a phenomenon that may have been due to several factors: hypercatabolism of the drug with prolonged administration, abnormality of liver function, variation in levels of serum albumin, fluctuations in drug dosage secondary to oral administration, and variations in dietary vitamin K. Protein C determinations by immunologic and functional assays consistently showed detectable but reduced protein C antigen levels with undetectable activity levels, suggesting that a dysproteinemia rather than a deficiency of synthesis is responsible for the child's coagulopathy.