B-cell epitopes of the allergen Chi t 1.01: peptide mapping of epitopes recognized by rabbit, murine, and human antibodies.

BACKGROUND: Chi t 1.01, a hemoglobin of the midge Chironomus thummi thummi, is a widespread environmental and occupational allergen. The aim of the present investigation was to identify and compare peptides involved in B-cell epitopes of Chi t 1.01 recognized by 15 human IgE sera, six murine monoclonal antibodies (mAbs), and a polyclonal rabbit antiserum. METHODS: Synthetic peptides 19-21 amino acids long covering the whole Chi t 1.01-sequence were covalently coupled to activated paper disks as well as adsorbed to wells of immunoplates and used for enzyme-linked immunosorbent assay. For fine epitope mapping, we used overlapping synthetic octapeptides with one amino-acid offset. RESULTS: Peptides containing the amino acids 13-17, 23-29, and 40-50 were recognized by three of the mAbs, while three other mAbs reacting with none of the peptides obviously recognized conformational epitopes. Binding sites for rabbit antibodies and for human IgE antibodies were scattered over the whole molecule. The peptide 80-100 seemed to comprise at least one important IgE epitope. Depending on the method of antigen binding to the solid phase, differing results were obtained. CONCLUSIONS: Several linear epitopes in Chi t 1.01 are recognized by human IgE antibodies, by mAbs, and by polyclonal rabbit antibodies. In addition, the results indicate the presence of conformational epitopes.

Cytokine depot formulations as adjuvants for tumor vaccines. I. Liposome-encapsulated IL-2 as a depot formulation.

In an attempt to mimic cytokine gene-transfected tumor cells and to develop an alternative approach to cancer immunotherapy, the authors vaccinated mice with mixtures of inactivated tumor cells and cytokine-containing depots. The RenCa mouse renal carcinoma and the B16 mouse melanoma were used as animal tumor models, with interleukin-2 (IL-2) as a cytokine and liposomes as a depot form. The results obtained show that vaccines consisting of mixtures of irradiated tumor cells and cytokine-containing liposomes can be used as highly effective tumor vaccines. These vaccines are very easy to prepare and, in contrast to vaccines consisting of cytokine gene transfected tumor cells, their composition (cell dosage, cytokine dosage) can be easily varied. Vaccination efficiency depended on (a) on the immunogenicity of the tumor cells: RenCa tumor cells are more immunogenic than B16 melanoma cells; (b) vaccination frequency: a single vaccination with irradiated tumor cells and 10 micrograms of IL-2 in liposome-encapsulated form was sufficient to induce lasting protective immunity against the RenCa tumor, whereas several (four to six) vaccinations in weekly intervals were needed to obtain a similar degree of protective immunity to the B16 melanoma; and (c) the dose of the cytokine encapsulated in the admixed liposome depots: immunity to the tumors could be induced only within a narrow cytokine-dose range ("IL-2-dose window"). The results obtained indicate that, because of the easiness of preparation and handling, vaccine formulations consisting of irradiated tumor cells and IL-2 in depot formulations are candidates for tumor vaccines for the treatment of tumor patients.

Urinary antigens as markers of papillary toxicity. II: Application of monoclonal antibodies for the determination of papillary antigens in rat urine.

We have previously reported the preparation of monoclonal antibodies specific for antigens localized in the rat renal papilla. Three of the monoclonal antibodies reacting with antigens localized in papillary and cortical collecting duct epithelia were selected for the development of enzyme-linked immunosorbent assay (ELISA)-type assays. The papillary antigens ('PapA') determined in these tests were designated PapAl (applying the monoclonal antibody PapX 5C10), PapA2 (applying the monoclonal antibody PapX 12F6), and PapA3 (applying the monoclonal antibody PapXI 3C7). Using these assays antigen excretion was determined in the urine of rats. Depending on the test compound used. the application route, and the dose, the observed antigen release patterns differed. Whereas after a single intraperitoneal application of 2-bromoethanamine or of propyleneimine an increased release of PapA1 but not of the two other antigens was observed oral application of bromoethanamine had minor effects. In contrast, both a single intraperitoneal application or repeated oral applications of indomethacin resulted in an increased release of all the three antigens. Daily application of ipsapirone in the diet or in drinking water resulted in significantly elevated urinary release of PapAl which increased incrementally for the duration of the application. Release of PapA2 and PapA3 was not affected and remained in the normal range. These results show that with the tests developed changes in the rat renal papilla caused by xenobiotics can be detected early by urinary analysis and monitored during follow-up studies. Moreover. the different antigen release patterns obtained after application of the different compounds suggest a possible differing mode of action.

Urinary antigens as markers of papillary toxicity. I. Identification and characterization of rat kidney papillary antigens with monoclonal antibodies.

Monoclonal antibodies were prepared in an attempt to develop diagnostic tools for the identification of toxic damage to the rat renal papilla. One IgG and five IgM monoclonal antibodies, reacting with antigens localized in the papilla were obtained. Three of the IgM class and the IgG class monoclonal antibodies were found to be specific for antigens localized in collecting ducts, two of them staining papillary collecting ducts more intensely than cortical collecting ducts. The IgG class antibody, termed Pap X 5C10, recognizes an antigen located at high density on the luminal side of papillary collecting duct epithelial cells and at lower density in cortical collecting duct cells. One of the IgM class monoclonal antibodies reacts with an antigen localized in epithelial cells as ascending and descending loops of Henle and of connecting tubules. Another of the IgM class monoclonal antibodies reacts with an antigen localized in the interstices of the inner medulla. All these monoclonal antibodies react with their antigens in native frozen as well as in Bouin-fixed and paraffin-embedded tissue slices. Molecular properties of the Pap X 5C10 antigen have been investigated by gel permeation chromatography, SDS-PAGE, Western blotting, and isoelectric focusing. The results indicate that the antigen in both its tissue-derived and urinary form is of large (150-200 kDa) molecular size and can be separated into two molecular species with isoelectric points of pH 7.2 and 7.3 respectively. In the urine the antigens recognized by the monoclonal antibodies form large complexes with Tamm-Horsfall protein. The antigen-containing complexes can be extracted from urine by adsorption to diatomaceous earth and elution with SDS-containing buffer. Using sandwich ELISA-type assays it is possible to determine the concentration of the antigens. In preliminary experiments we were able to show that at least three of the antigens are detected in the urine following toxic insults to the kidney. The monoclonal antibodies prepared and the tests developed thus may provide direct diagnostic access to the renal papilla and allow, for the first time, early detection of papillary damage.

In vitro production of monoclonal antibodies in high concentration in a new and easy to handle modular minifermenter.

This paper describes a new and easy to handle reusable minifermenter for high-density culture of hybridoma and other cells. The culture apparatus is composed of two modules: a 40 ml disposable cell culture and antibody production chamber (the 'production module') and a 550 ml medium reservoir (the 'supply module'). The two modules are separated from each other by a dialysis membrane allowing passage of low molecular mass nutrients and metabolites. The monoclonal antibodies are produced and enriched in the production module. The outer part of this module is made from a thin gas-permeable silicone rubber membrane allowing exchange of gases (oxygen and carbon dioxide). To start the culture, the cells are injected into the production module through ports in the silicone rubber which are equipped with Luer Lock connectors. Samples can be removed in the same way. For culturing, the minifermenter is rolled on a roller apparatus in a carbon dioxide-supplied incubator. Depending on the individual properties of the hybridoma cells cultured, cell densities of more than 10 x 10(6) (in some cases up to 35 x 10(6)) cells per ml and monoclonal antibody concentrations of several mg per ml can be obtained in the new minifermenter. On average, 61 mg (range: 9-159 mg) could be produced within 1-4 weeks. In terms of their properties the monoclonal antibodies produced in the new modular minifermenter were indistinguishable from antibodies prepared from ascitic fluid or from the supernatant of conventional stationary culture. The culture method is a useful alternative to the in vivo production method in mice. In addition, it represents a completely new, inexpensive and easy to handle general solution to the problem of culturing cells in high density and obtaining cellular products in high concentrations.

A simple and inexpensive high density dialysis tubing cell culture system for the in vitro production of monoclonal antibodies in high concentration.

This paper describes the construction and application of a low-cost roller bottle-like culture appliance in which hybridoma cells can be cultivated in high density in dialysis tubing. The appliance facilitates the simultaneous culture of up to four cell lines yielding 50 ml culture volume of each. Samples for follow-up analysis of the cultures can easily be taken when needed through sample ports. In order to obtain high cell densities (at least 10(7) cells/ml), high cell viability (at least 50%) and high antibody yield (at least 1.0 mg/ml) the bottle is rolled at a speed of 4-6 rpm and is gassed continuously by a micropump driven by rechargeable NiCd batteries fixed to the culture flask. Depending on the individual properties of the hybridoma lines tested, the cells may be cultured for 1-2 weeks, and cell densities of up to 30 x 10(6) cells/ml with viabilities of approximately 50% and monoclonal antibodies in concentrations of up to 2.8 mg/ml may be obtained. In their properties the monoclonal antibodies produced by this in vitro procedure are indistinguishable from those prepared in the form of conventional stationary culture supernatant or of ascitic fluid. Specific antibody content is within the same range as in ascitic fluid. Consequently, the monoclonal antibodies can be purified in one step, e.g., by ion exchange chromatography from the culture supernatant. Therefore, the newly developed culture device and the culture method described is a useful alternative to ascites production in live mice.

Preparation and characterization of a mouse monoclonal antibody against a rat kidney papillary antigen.

Monoclonal antibodies were prepared in an attempt to develop diagnostic tools for the identification of toxic damage to the renal papilla. One of these antibodies, termed PAP X 5C10, recognizes an antigen that is located on the luminal side of collecting duct epithelial cells. As shown by Western blotting experiments, this antigen can be extracted from papillary tissue and visualized as a broad band of high molecular weight. Enzyme-linked immunosorbent assays have shown that increased amounts of this antigen can be detected in urine of rats treated with bromoethaneamine. This procedure thus enables this antigen to be detected also in supernatants of cultured ductal cells.

Phenotypic characterization of three long-term-cultured murine resident macrophage lines.

The antigenic phenotypes of three long-term cultured murine resident macrophage lines selected in vitro from cell suspensions of different tissues--namely MAY 1 (from the peritoneal cavity), MASP (from the spleen) and MALU (from lung tissue)--were determined using a panel of monoclonal antibodies. The results indicate that all three cell lines belong to the mononuclear phagocyte system and express characteristics indicating a rather high differentiation state. However, there was a significant difference in antigen expression between the two macrophage lines obtained from solid tissues (MASP from spleen and MALU from lung), which were very similar in their antigenic pattern, and the MAY 1 line obtained from the peritoneal cavity, which seemed to be less well differentiated. The antigenic profile of the "mesothelial" cell population associated with the MASP line indicates that this cell population is difficult to characterize and to include in a particular lineage.

A species and organ specific glomerular basement membrane antigen.

By the use of a monoclonal antibody reacting with the human glomerular basement membrane exclusively we have been isolating a specific glomerular antigen. The antibody failed to react with other renal structures and other basement membranes and extracellular matrix constituents of other organs or plasma proteins. It did not react with glomerular basement membranes of other species as mice and rats. For the isolation of the antigen we applied affinity chromatography, on Sepharose beads coupled to the monoclonal antibody PM II 34 G3. From this column the antigen was eluted under acid conditions. In 8% polyacrylamide gel electrophoresis the approximate molecular weight was estimated with 14400 daltons, which was confirmed on high pressure liquid chromatography using the Bio-Sil TSK method. The antigen was temperature sensitive in that at high temperatures (60 degrees C) several bands on SDS-PAGE and several peaks on HPLC could be noted. This could be responsible for the crystal formation after treatment/concentration on the rotary vacuum pump at 60 degrees C. Preliminary data of amino acid analysis showed a high glycine content pointing towards a collageneous molecule. But cross reactivity with many connective tissue proteins could be ruled out by immuno-histochemical techniques and affinity chromatography. A major point of interest is that this antigen can be detected in human urine under physiological conditions. We are herewith reporting the first species and organ specific glomerular basement membrane antigen.

Characterization of mouse macrophage differentiation antigens by monoclonal antibodies.

Monoclonal rat antibodies to mouse macrophage antigens were prepared. For immunization phagocytic cells in the spleens of mice recovering from sublethal irradiation were used. Specificities of the monoclonal antibodies obtained were determined on cells of normal mouse cell populations as well as on cells of a panel of mouse cell lines. In an attempt to monitor expression of differentiation-related antigens two models of in vitro-induced macrophage differentiation were used: differentiation of cells of the myeloblast line Ml; CSF-1-induced differentiation of bone marrow cells. The results obtained clearly show that during maturation from undifferentiated to highly differentiated cells of the macrophage lineage expression of antigens recognized by the MIV 38, MIV 55, MV 87, and MV 114 monoclonal antibodies is enhanced. At the same time, expression of antigens recognized by the MIV 52, MIV 113, and MIV 116 monoclonal antibodies diminishes at a similar rate. The suitability of these monoclonal antibodies for the characterization of differentiation states of mouse macrophages is discussed.

Renal tolerance of fleroxacin in healthy volunteers.

In order to evaluate kidney tolerance of fleroxacin, a new fluoroquinolone, we performed a volunteer study with 16 healthy males, 20-27 years old. On three consecutive days 800 mg of fleroxacin was administered orally. Alanine-aminopeptidase and distal- and pan-tubular antigens were determined in 24 h urine collections with specific monoclonal antibodies. Routine haematological and biochemical parameters were determined daily and were in the normal range during the follow-up. No significant changes in excretion of alanine-aminopeptidase and of the urinary antigens were observed during the three days of fleroxacin administration and on the following three days. The results obtained in this volunteer study indicate that fleroxacin has no nephrotoxic side effects.

Serological characterization of macrophage hybridomas: identification of an interferon-gamma-inducible surface marker.

Macrophage hybridoma clones prepared by fusion of splenic adherent cells with P388D1 tumor cells have previously been shown to be heterogeneous with respect to function at the clonal level. In this study the macrophage clones were phenotypically characterized by indirect RIA using a battery of rat MAbs to murine myeloid and lymphoid cell surface markers. All macrophage clones expressed the common leukocyte antigen T200 and the Mac-1 alpha and beta chains. Markers which were differentially expressed among the clones included class II antigens and the antigens detected by MAbs MIV 55, MIV 38, and 14G8. The antigens detected by the latter three MAbs were referred to as MBR-1, -2 and -3, respectively. Functional heterogeneity did not correlate with phenotypic heterogeneity among the macrophage clones. Treatment of macrophage clones with IFN-gamma resulted in a significant increase in the expression of class II antigens and induced the expression of MBR antigens on some clones which were constitutively negative for these markers. The clonal distribution and induction patterns of class II antigen as compared to MBR antigen indicated that regulation of expression of these markers was independent. In addition, the clonal distribution and induction pattern of MBR antigens, along with competitive binding studies using radiolabeled MIV 38 and 14G8 MAbs, suggested that the three MBR antigens were similar or closely associated molecules.

Investigation on renal tolerability of ciprofloxacin with tests based on monoclonal antibodies.

The results obtained during the investigation on the excretion of nine urinary antigens originating in the kidney and characterized by monoclonal antibodies and of the brush-border marker-enzyme alanine aminopeptidase in the urine of 12 volunteers before and during the administration of therapeutic doses of ciprofloxacin on seven consecutive days gave no indication that this drug exerts tubulo-toxic side effects. The mean excretion curves showed no significant increases during ciprofloxacin treatment for any of the nine kidney-derived antigens. The measured antigen-excretion courses correlated with the curve of the excretion of AAP, which was measured as a marker for the brush border of the proximal tubule, and also with the course of the fluid elimination. There was no indication of selective damage to the distal section of the tubular apparatus resulting from possible crystalluria. These results, as well as the fact that all the other laboratory parameters were within the normal range, indicate that the kidney function of the volunteers was normal during the observation period and that ciprofloxacin is tolerated by the kidney.

Identification of fragments of proximal and distal tubular cells in the urine of patients under cytostatic treatment by immunoelectron microscopy with monoclonal antibodies.

In an attempt to identify the origin of cellular fragments released in the urine of patients treated with potentially nephrotoxic drugs such as cytostatics, two monoclonal antibodies were applied: monoclonal antibody PM II 9 C2, directed against an antigen in distal tubular cells; and monoclonal antibody PM II 39 H11 specific for an antigen in proximal tubular cells. The specificities of both monoclonal antibodies were elaborated in the indirect as well as in the direct immunofluorescence technique. Both antibodies were then used to identify cellular fragments obtained from the urine of patients treated with cytostatic drugs by ultracentrifugation. By application of the indirect immunogold method, it was shown that material of proximal as well as distal tubular origin was shed by the damaged cells. Whereas the proximal tubular antigenic epitope recognized by PM II 39 H11 was always found in large irregular complexes of debris-containing vesicles, the distal tubular antigenic epitope recognized by PM II 9 C2 was always found associated with filament-like regular structures. This is the first report in which excretion of components of distal tubular cells is demonstrated as a consequence of the nephrotoxic side effects of cytostatic treatment. With the help of monoclonal antibodies, it has now become possible to identify and to investigate the damage inflicted on the distal part of the tubule system in addition to the well-documented proximal tubular damage.

Kidney-derived urinary antigens assayed with monoclonal antibodies for the detection of renal damage.

For the quantitation of kidney-derived Urinary Antigens (UA) monoclonal antibodies specific for antigens localized in cells of defined subunits of the nephron were applied in sandwich ELISA. Antigen excretion was measured in the urine of healthy individuals, patients suffering from various diseases, kidney transplant recipients, and healthy volunteers receiving therapeutic doses of antibiotic drugs. In healthy individuals, in patients with diseases primarily affecting the glomerulus, and in inactive phases of chronic diseases antigen excretion was low. Toxic drug effects enhanced antigenuria. Excretion of some or all of the antigens always indicated tubular alterations. The tests thus provide information on location and extent of acute primary tubular damage.