Spectral characterization of environment-sensitive adducts of interleukin-1 beta.

We have determined the fluorescence properties of two covalently attached acrylodan derivatives of recombinant human interleukin-1 beta, namely the Cys-8 and Lys-103 adducts. The emission and excitation maxima indicated the presence of two operationally distinct conformers for each probe. The iodide quenching and the kinetics of fluorescence changes associated with guanidinium chloride-induced denaturation show that each covalent adduct exists both in hydrated and dehydrated environments. Furthermore, fluorescence changes associated with the binding of the adducts to a recombinant soluble murine receptor indicated that only the conformers with the label in the hydrophobic environment are competent toward the soluble murine interleukin receptor and that the hydrated and dehydrated conformers are in a dynamic equilibrium on the time scale of the binding experiments.

Effects of lectins and tunicamycin on IL-1 binding to YT cells.

Specific binding of iodinated-interleukin-1 alpha or beta to YT cells could be inhibited by the lectins wheat germ agglutinin (WGA) and concanavalin A (Con A). WGA and Con A inhibition of IL-1 binding was abrogated by previous exposure of these plant proteins to the lectin-specific sugars N-acetylglucosamine (GlcNAc) and methyl glucoside (MG), respectively. Tunicamycin, an inhibitor of glycosylation, decreased interleukin-1 (IL-1) binding to YT cells, but also reduced total protein synthesis. These observations suggest that carbohydrate moieties on or near the interleukin-1 receptor may be important for optimal receptor binding of IL-1 to intact YT cells.

Pharmacological inhibition of interleukin-1 activity on T cells by hydrocortisone, cyclosporine, prostaglandins, and cyclic nucleotides.

The effects of a panel of hormones and pharmacological agents on the activation of T cells by a combination of interleukin-1 and phytohemagglutinin (IL-1/PHA) was studied. Pharmacological effects on various stages of IL-1/PHA-induced interleukin-2 (IL-2) production by the cloned murine thymoma cell line LBRM-33-1A5.7 were dissected using a multi-step assay procedure. A 4-h lag phase in the kinetics of IL-2 production allowed the operational definition of an early, IL-1-dependent programming stage, followed by an IL-2-production stage of the assay. A cell-washing procedure between these stages was introduced in order to distinguish IL-1 receptor antagonists from functional IL-1/PHA antagonists. Hydrocortisone and cyclosporine were potent inhibitors (active in the nM range) of both stages of IL-2 production, suggesting that neither is an IL-1 receptor antagonist. The cyclic adenosine monophosphate (cAMP)-elevating agents prostaglandin E2, dibutyryl cAMP, and theophylline inhibited IL-2 production during the early, IL-1-dependent programming stage. By contrast, prostaglandin F2 alpha and dibutyryl cyclic guanosine monophosphate did not appreciably inhibit IL-1/PHA activity. These results are discussed in relationship to the effects of these test agents in thymocyte IL-1 assays or mitogenesis assays and the implications toward understanding the mechanisms underlying IL-1/PHA activation of T cells.

Crystallization of purified recombinant human interleukin-1 beta.

The gene for human interleukin-1 beta was cloned from SK-hep-1 hepatoma cellular RNA and expressed at high levels in Escherichia coli both as the naturally processed form (rIL-1 beta) and as a variant with an additional sequence of three amino acids on the N-terminus (rIL-1 beta +). Expressed protein was purified to homogeneity by a sequence of steps, which included low pH incubation, adsorption and desorption from Procion Red Sepharose, sizing on a Superose 12 fast-performance liquid chromatography (FPLC) column, and anion exchange chromatography on QAE Sepharose. The final step provided a biologically active protein that migrates on two-dimensional (2-D) gels as a single spot with a pI of 6.7 +/- 0.2 and a molecular mass of 17,500 daltons. Concentrated solutions of rIL-1 beta have produced crystals by ammonium sulfate precipitation. The crystals are tetragonal, show the symmetry of space group P4(1) or its enantiomer, have lattice constants of a = 58.46 (1) and c = 77.02 (3) A, and scatter to at least 2 A resolution. A structure determination based on these crystals is under way.

Unbalanced X chromosome mosaicism in B cells of mice with X-linked immunodeficiency.

The immunodeficiency in CBA/N mice is reflected by abnormal development of a subset of B lymphocytes. However, it is not clear how xid, the mutant gene in CBA/N mice, affects the development of this subset. Specifically, it is not known if the xid gene influences the development of the B cell subset directly or indirectly by providing the improper developmental milieu through effects on other cells. We investigated this question using female mice heterozygous for two x chromosomal genes, xid and Pgk-1 (phosphoglycerate kinase-1). Since females are mosaic because of x chromosome inactivation, their lymphocytes can be studied for the choice of the x chromosome, using the two PGK-1 isoenzymes as the cytological marker. We find that B lymphocytes in the spleen prefer the x chromosome without xid while the remaining splenocytes and cells from other tissues do not. This suggests that xid affects B lymphocytes directly and not through their developmental milieu. Furthermore, our data suggest that the precursors for IgG1- and IgG3-producing cells may be both few and different.

The H-2Kk antigen: isolation using monoclonal immunoadsorbent chromatography and sequence analysis without radioisotopes.

Monoclonal immunoadsorbent chromatography has been used to isolate milligram quantities of detergent-solubilized H-2Kk antigen. Using the procedure described in this paper 10(12) cells may be processed yielding 10 mg of homogenous H-2Kk which represents 70% of the allotypic serological activity present in the original homogenate. NH2-Terminal sequence data of the first 30 residues of the H-2Kk heavy chain are presented. The cell line selected as the source of antigen and the criteria of purity of the antigen have been found to be critical as proteins of molecular weight 42,000 and 12,000 were copurified with H-2Kk from the BW5147 cell line. The additional components were observed in gradient gel electrophoresis or two-dimensional electrophoresis, but not in conventional Laemmli gel electrophoresis.

Monoclonal and allospecific H-2Kk antisera precipitate a high molecular weight protein.

A protein with an apparent m.w. of 68,000 has been observed in immunoprecipitations of NP-40 solubilized BW5147 thymoma cells by using monoclonal or polyclonal allospecific H-2Kk antisera. By contrast, H-2Dk alloantisera precipitated a 45,000 m.w. protein from the same membrane preparations. The 68,000 m.w. protein is expressed on the plasma membrane as determined by vectoral labeling. Extensive clearing experiments and the use of monoclonal antibody demonstrate that the protein does not bear group-specific C-type viral determinants.

Radioimmunoassay of the link proteins associated with bovine nasal cartilage proteoglycan.

Link proteins from bovine nasal cartilage have been purified by preparative polyacrylamide gel electrophoresis in sodium dodecyl sulfate (Baker, J.R., and Caterson, B. (1979) J. Biol. Chem. 254, 2387-2393) and used to raise antisera in rabbits. A sensitive radioimmunoassay procedure utilizing binding of 125I-labeled antigen . antibody complexes to Protein A of Staphylococcus aureus has served to demonstrate the specificity of the antisera for the link proteins. The lack of reactivity with proteoglycan fractions indicates that link proteins and proteoglycan do not share antigenic determinants. This result is in accord with published cyanogen bromide peptide cleavage data (Baker, J.R., and Caterson B. (1977) Biochem. Biophys. Res. Commun. 77, 1-10) which showed proteoglycan and link protein to be structurally dissimilar. The radioimmunoassay procedure has been used to quantitate small amounts of link protein which remain associated with proteoglycan after purification by equilibrium density gradient centrifugation in 4 M guanidine HCl and by gel chromatography in sodium dodecyl sulfate.