ISOLATION OF A SOLUBLE TRANSPLANTATION ANTIGEN

Fifty years in the vineyard of transplantation: looking back

The past 5 decades have documented remarkable advances in basic knowledge and clinical expertise in transplantation. The first 12 years of this half century of my participation in the enterprise were consumed with the isolation, chemical characterization, and application of histocompatibility antigens purified from mouse, guinea pig, and human tissues, demonstrating that their specificity was based on unique amino acid sequences in protein structures. Initial unsuccessful attempts to use native molecules to induce tolerance in rat renal or heart transplantation models were followed by limited success when they were administered with a brief perioperative course of cyclosporine (CsA). Production of allochimeric constructs of class I major histocompatibility complex molecules bearing donor-type amino acid substitutions into the host-type C-terminal portion of the α1 helix yielded tolerogens whose activity was not dependent on conditioning with CsA or total lymphoid irradiation (TLI). The allochimeric molecules serve as altered peptide ligands that induce an aberrant T-cell signal 1 response producing transplantation tolerance. The potent activity of CsA in this experimental model was extended to clinical settings. Pharmacologic tools were employed to explore intra- and interindividual variations in drug exposure leading to the development of a better drug formulation. However, the intrinsic nephrotoxicity of CsA necessitated marked 80% reductions in de novo drug exposure as were achieved by exploiting the synergistic pharmacodynamic and pharmacokinetic interactions of CsA with sirolimus. The final decade in this 50-year experience includes editorship of this journal with marked changes in its direction. These experiences have afforded insights into future avenues for preclinical exploration and therapeutic drug development.

Noncytolytic extraction of cell surface antigens using butanol

Incubation of viable tumor cells in single-phase aqueous solutions of 1-butanol releases a subset of peripherally-associated membrane proteins. Among the extracted components are tumor-specific and tumor-associated antigens of several human and experimental neoplasms. The extraction technique is noncytolytic: extracted cells remain viable and proliferate both in vitro and in vivo. Examination of the denuded cells has elucidated several important differences in cell-surface phenotype that have proved useful in studying the biology of such diverse systems as cellular communications and the mechanisms of hematogenous metastasis. It is anticipated that noncytolytic butanol extraction will continue to prove a powerful approach for the isolation and characterization of a variety of cell-surface antigens.

Purification of tumor-specific antigens. An overview of the relevance to human colon carcinoma

Methods which dissociate intramolecular noncovalent bonds have been used to prepare soluble derivatives of cell-surface antigens. Applications of these techniques to human colon carcinoma are underway. Continuous tissue-culture strains derived from primary lesions were developed and shown to be composed of malignant epithelial elements. Parallel data on the preparation and activity of soluble materials in a murine model methylcholanthrene system reveal that although cultured cells are a satisfactory source for antigen extraction, they are poor targets of the immune response. The development of methods to quantitate the biologic activity of colon-specific, soluble materials may provide indicator systems to define the antigenic determinants, to permit purification, and to serve as assays of the efficacy of immunotherapy.

Preparation of dialyzable histocompatibility antigen from BALB-c mice (cell-membrane fragments-proteolytic digestion-detergent solubilization)

Histocompatibility antigens solubilized from cell-membrane fragments of BALB/c mouse spleen and liver, by Triton X-100 and butyl alcohol, were subjected to digestion by proteolytic enzymes in an effort to obtain smaller molecular species that retained antigenic activity. Digestion with both trypsin and papain yielded two antigens of smaller molecular weights that retained the specificity of BALB/c histocompatibility antigen, as determined by the inhibition of allogeneic antibodies, agglutination of BALB/c erythrocytes, adsorption-hemagglutination versus the soluble histocompatibility antigen, and suppression of the ability of BALB/c spleen cells to produce hemolytic plaques to sheep erythrocytes. The two active products of trypsin digestion were, respectively, excluded by Sephadex G-50 but not by G-75, and excluded by G-25 but not by G-50. Papain digestion yielded one active antigen that was excluded by G-25 but not by G-50, and a smaller antigen that was excluded by G-10 but not by G-15 and, as determined by gel filtration, has a molecular weight slightly lower than vitamin B(12).

The effect of antigen pretreatment on canine renal allograft survival

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Solubilization of IgM-kappa specific surface material from Burkitt lymphoma cell lines

Two Burkitt lymphoma (BL)-derived cell lines, characterized by the accumulation of IgM-κ reactive material in their cell membrane, and one BL-line with no such reactivity were studied. Attempts were made to isolate and further characterize the reactive membrane material. Pepain digests of crude membrane preparations from the surface reactive cell lines were capable of blocking the direct membrane fluorescence reaction while the digest obtained from the non-reactive line demonstrated no blocking activity. Gel filtered and papain digested membrane material, from all three cell lines, produced similar elution curves when rechromatographed on a calibrated Sephadex G-150 column. The membrane fluorescence blocking activity of papain digests, derived from cells with μ and κ chain reactivity, appeared to be associated with material of a molecular weight less than 50,000. When this gel filtered material, and the corresponding fraction from the non-reactive cell line, were subjected to polyacrylamide gel electrophoresis a difference in electrophoretic mobility was noted. Electron microscopy revealed small protein fragments, some of linear dimensions compatible with a molecular weight of roughly 50,000 and the majority even smaller in all three preparations. μ and κ chain reactivity was demonstrable by indirect haemagglutination only in papain digested and gel filtered fractions from the two membrane reactive cell lines. Haemagglutation inhibition with Fc μ fragments indicated that these fragments inhibited the anti-IgM reactivity of red cells coated with the proteolytic products of the two membrane reactive cell lines.

Chemical markers of transplantation individuality solubilized with sonic energy

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Serological and immunogenic activity of soluble mouse transplantation antigens controlled by the H-2 locus

The solubilization and partial purification of mouse transplantation antigens were monitored by (1) an in vitro assay for alloantigenic specificities and (2) an in vivo assay for transplantation antigens controlled by the H-2 histocompatibility locus. Antigens from A/J mice were solubilized by papain and fractionated on a Sephadex G-150 column. The eluate showed a 280 nm absorbance peak (F(1)) in the excluded volume and two peaks (F(2) and F(3)) in the included volume. H-2 specificities 1, 3, 4, 5, 11, 23, and 28 were confined to a single peak in the F(2) fraction. Fractions F(1), F(2), and F(3), were tested for their ability to accelerate skin graft rejection in noncoisogenic strains which differ at both H-2 and non-H-2 loci, and coisogenic strains which differ only at the H-2 locus. All fractions produced significant acceleration of graft rejection in the noncoisogenic strains, but only fraction F(2) produced significant acceleration in the coisogenic strains. These findings indicate that H-2 transplantation antigens detected by our in vivo assay, and H-2 alloantigenic specificities detected by our in vitro assay are solubilized by papain and are eluted in the same peak during Sephadex fractionation.

Purification of soluble murine transplantation antigens by isoelectric focusing

Hydrosoluble transplantation antigens were prepared from membranes and microsomes of C(3)H mice (BP8 tumoral cells) and purified by isoelectric focusing. A biologically active fraction which seems homogenous by acrylamide gel electrophoresis was characterized: it specifically inhibits anti C(3)H hemagglutinin antibodies and provokes a highly significant prolongation of skin graft.

Comparison of the peptide composition of two histocompatibility-2 alloantigens

The peptide composition of purified Histocompatibility-2 (H-2) reactive glycoprotein fragments from two murine strains allelic at the H-2 locus (H-2(b) and H-2(d)) were compared by a cellulose thin-layer peptide mapping micro technique. Approximately 70 per cent of the theoretical maximum number of peptides produced by cyanogen bromide cleavage and trypsin digestion were visualized by this technique. Most (38) of the peptides for the glycoproteins from these strains allelic for the H-2 locus were identical; however, three peptides of the H-2(b) and four peptides of the H-2(d) alloantigen were unique. The results demonstrate the remarkable similarity in protein structure between these two allelic products, but also show a small but reproducible difference in their peptide composition. The findings are consistent with the hypothesis that protein primary structure may determine wholly or in part their alloantigenic activities.