Gibberellin-regulated proteins: Emergent allergens

About 10 years ago, a protein family was shown for the first time to contain allergenic members, gibberellin-regulated protein (GRP). The first reported member was from peach, Pru p 7. One can hypothesize that it was not detected before because its physicochemical characteristics overlap with those of lipid transfer protein (LTP), a well-known allergen, or because the exposure to GRP increased due to an increase in the gibberellin phythormone level in plant food, either exogenous or endogenous. Like LTPs, GRPs are small cationic proteins with disulfide bridges, are resistant to heat and proteolytic cleavage, and are involved in the defense of the plant. Besides peach, GRP allergens have been described in Japanese apricot (Pru m 7), sweet cherry (Pru av 7), orange (Cit s 7), pomegranate (Pun g 7), bell pepper (Cap a 7), strawberry (Fra a GRP), and also in pollen with a restriction to Cupressaceae tree family (Cup s 7, Cry j 7, and Jun a 7). IgE cross-reactivities were described between GRPs, and the reported peach/cypress and citrus/cypress syndromes may therefore be explained because of these GRP cross-reactivities. GRPs are clinically relevant, and severe adverse reactions may sometimes occur in association with cofactors. More than 60% and up to 95% sequence identities are calculated between various allergenic GRPs, and three-dimensional models show a cleft in the molecule and predict at least three epitopic regions. The structure of the protein and its properties and the matrix effect in the original allergenic source should be unraveled to understand why, despite the ubiquity of the protein family in plants, only a few members are able to sensitize patients.

Identification of a polygalacturonase (Cup s 2) as the major CCD-bearing allergen in Cupressus sempervirens pollen

As IgE glyco-epitopes, also referred to as cross-reactive carbohydrate determinants (CCDs), can share significant structural homologies between different plants, they are prone to extensive cross-reactivity among allergen pollen extracts. Here, cypress pollen allergens, especially a polygalacturonase (PG), were further characterized using double one-dimensional electrophoresis (D1-DE). The presence of specific IgE directed against CCDs was investigated by bromelain IgE inhibition and concanavalin A binding assays using sera of cypress pollen-sensitized patients. Our results showed that IgE reactivity to CCDs in Cupressus sempervirens pollen extracts is mainly related to bromelain-type epitopes of a newly identified cypress PG. This glycoprotein has been further characterized through an immunoproteomic approach and officially indexed as Cup s 2 by the WHO/IUIS allergen nomenclature. Cup s 2 could thus be associated with the increased prevalence of IgE reactivity to cypress pollen extracts because of CCD interference.

Complementarity between microarray and immunoblot for the comparative evaluation of IgE repertoire of French and Italian cypress pollen allergic patients

Cypress pollen represents the primary cause of respiratory allergies in Mediterranean areas. Patients allergic to Cupressus sempervirens pollen (Cups) (CPA) can be discriminated on the basis of the immunoglobulin E (IgE) binding to a basic 14 kDa protein (BP14) or to high-molecular-weight (HMW) glycoproteins only. Specific IgE repertoires of two differentially exposed CPA cohorts, French and Italian, were investigated using an IgE microarray system (some known major allergens from several allergenic sources) and individual IgE immunoblotting (IB) of whole Cups pollen extract separated by SDS-PAGE (all allergens from one allergenic source: cypress pollen). The prevalence of sensitization to BP14 was higher in French (37 %) than in Italian patients (17 %) and major differences were observed in IgE reactivities to lipid transfer proteins (LTPs). Thirty percent of the Italian CPA (4 % in the French group) had specific IgE against the Parietaria pollen LTP, independently of IB subgroups. Regarding peach LTP sensitization, all Pru p 3+ Italian CPA (10 %) were in the HMW+ subgroup, while Pru p 3+ French CPA (20 %) were all included in the BP14+ subgroup. BP14 sensitization is likely a marker of Cups exposure and is, in French CPA, significantly correlated to Pru p 3 sensitization. The IgE immunoblot and microarray are complementary tools that highlight differences in the subtle sensitization profile between groups of patients in comparative studies.

Immunodominant semen proteins II: contribution of seminal proteins to female immune infertility

Seminal fluid is a protective medium for sperm, but it also represents potential immunogenic structures for the female immune system. Anti-seminal antibodies may threaten early fertilization. The aim of our work is to detect and identify seminal proteins that are related to female isoimmunization. In this report, we quantified serum anti-seminal IgG antibodies. Seminal proteins were analysed by two-dimensional gel electrophoresis followed by immunoblotting. To identify IgG-binding proteins of interest, a proteomic approach was selected. The dominant seminal antigens were detected within the relative molecular mass ranging from 25 to 85 kDa and the isoelectric point from 5 to 7. The detected proteins were further identified as prostate-specific antigen, prostatic acid phosphatase, zinc-α-2-glycoprotein and zinc finger protein 778. Since these proteins were recognized by IgGs produced by infertile women and not by fertile women, we presume that major seminal antigens may play an important role in the pathogenesis of female immune infertility. Our study suggests the pattern of seminal proteins for further therapeutic attempts in the diagnosis of female immune infertility.

Patterning of polystyrene by scanning electrochemical microscopy. Biological applications to cell adhesion

Polystyrene surfaces may be patterned by Ag(II), NO(3)(•), and OH(•) electrogenerated at the tip of a scanning electrochemical microscope. These electrogenerated reagents lead to local surface oxidation of the polymer. The most efficient surface treatment is obtained with Ag(II). The patterns are evidenced by XPS and IR and also by the surface wettability contrast between the hydrophobic virgin surface and the hydrophilic pattern. Such Ag(II) treatment of a polystyrene Petri dish generates discriminative surfaces able to promote or disfavor the adhesion of proteins and also the adhesion and growth of adherent cells. The process is also successfully applied to a cyclo-olefin copolymer and should be suitable to pattern any hydrogenated polymer.

Evaluation of ash pollen sensitization pattern using proteomic approach with individual sera from allergic patients

BACKGROUND

In Europe, sensitization to ash pollen induces pollinosis with cross-reactivities with other pollen sources. The aim of the study was to identify the repertoire of ash pollen allergens and evaluate the extent of the diversity of the IgE response in ash allergic patients.

METHODS

The IgE reactivities of 114 ash pollen- and eight grass pollen-sensitized patients were screened by 1D immunoblot (SDS-PAGE) against ash pollen extract. The IgE reactivities of 13 ash pollen- and two grass pollen-sensitized patients were then evaluated in 2D immunoblots. Some IgE- and non-IgE-reactive proteins were identified by mass spectrometry.

RESULTS

In 1D analysis, 86% of sera showed binding to Fra e 1 (18-20 kDa), 23% to Fra e 2 (14 kDa), 3% to Fra e 3 (10 kDa) and 57% to High Molecular Weight allergens (HMW, >30 kDa). Individual analysis of 2D immunoblots showed several IgE-binding protein areas among which three were more often recognized: (i) Fra e 1 comprising, at least, 15 isoforms, (ii) a series of acidic spots (45 kDa), and (iii) Fra e 2, the ash profilin. HMW allergens could be resolved in four areas; two unidentified, one homologous to beta-galactosidase and the other to sugar transport proteins. A malate deshydrogenase and calmodulin were shown to be IgE-binding proteins and 10 non-IgE reactive proteins were identified.

CONCLUSIONS

No direct correlation was evidenced between IgE profile and the degree of sensitization even though 2 spectrotypes could be distinguished. Our data contribute to a better delineation of ash pollen allergens and patterns of sensitization.

Lipid transfer protein 1 is a possible allergen in Arabidopsis thaliana

BACKGROUND

The Arabidopsis thaliana genome was recently fully sequenced, and this plant is now considered as the most useful model to study the effects of genetic engineering. The aim of the present study was to identify A. thaliana IgE-binding molecules and to localize their genes in order to evaluate the potential effect of gene insertion on the expression of IgE-binding molecules.

METHODS

A. thaliana flower proteins were separated by two-dimensional gel electrophoresis and transferred onto a nitrocellulose sheet. The nitrocellulose sheet was successively incubated with human sera known to contain IgE that binds to rapeseed proteins, alkaline phosphatase-conjugated goat anti-human IgE and 5-bromo-4-chloro-3-indolyl phosphate and nitroblue tetrazolium. One allergen was further identified by N-terminal amino acid microsequencing.

RESULTS

The results showed that some individuals possessed IgE that recognized numerous proteins with high molecular masses and various isoelectric points. This binding pattern strongly suggests that the epitopes recognized by these IgE could be, at least partly, sugar residues. Otherwise, out of the 10 sera that possessed IgE to Arabidopsis flower proteins, one serum strongly recognized a unique basic protein with an apparent molecular mass of around 14 kD. This protein was identified by amino acid microsequencing as the lipid transfer protein 1 (LTP1).

CONCLUSION

We have demonstrated that A. Thaliana LTP1 is IgE reactive. The gene encoding this protein is located on chromosome 2, but it has been described that family 1 of A. Thaliana LTPs constitutes a multigenic family with genes located on various chromosomes.

Polygalacturonase (pectinase), a new oilseed rape allergen

BACKGROUND

Type I hypersensitivity to rapeseed pollen allergens was described as the result of a cross-sensitization with various pollens that could constitute an aggravating factor in birch or grass pollen allergies. Recently, a few rapeseed pollen allergens were described. The aim of the present work was to identify new rapeseed pollen allergens by using two-dimensional gel analysis, microsequencing, and mass spectrometry.

METHODS

Water extractable proteins from oilseed rape pollen or stamen were separated by two-dimensional gel electrophoresis. The proteins were then electroblotted onto a nitrocellulose (NC) sheet. The NC sheets were successively incubated with (1) individual human sera pre-selected for their immunoglobulin E (IgE) reactivity to rapeseed pollen proteins, (2) alkaline phosphatase (AP)-conjugated goat anti-human IgE and (3) AP substrate. The allergens localized by this method were then identified by microsequencing and MALDI-TOF mass spectrometry analysis.

RESULTS

Of the 18 sera studied, five recognized a wide multispot zone with a molecular mass around 43 kD and pIs between 6.5 and 8.5. The results obtained with two representative sera are shown. From this zone, two isoforms of the polygalacturonase enzyme were identified by microsequencing. Confirmation was obtained through MALDI-TOF mass spectrometry analysis.

CONCLUSION

The present results allow the identification of a new rapeseed allergen that can be the main allergen for some patients.

Geometric torsion in idiopathic scoliosis: three-dimensional analysis and proposal for a new classification

STUDY DESIGN

Three-dimensionally reconstructed spines of 62 subjects with idiopathic scoliosis were reviewed for three-dimensional pattern classification based on the measurement of geometric torsion.

OBJECTIVES

To evaluate the relevance of geometric torsion as a three-dimensional index of scoliosis, and to develop a three-dimensional classification of deformity for idiopathic scoliosis as opposed to the current classifications based on two-dimensional frontal views.

SUMMARY OF BACKGROUND DATA

Attempts have been made to measure the geometric torsional shape of scoliotic curves represented curvilinearly. However, the geometric torsion phenomenon has never been properly analyzed and thus has never been precisely defined.

METHODS

Standardized stereoradiographs of 62 patients with idiopathic scoliosis were obtained and used to generate three-dimensional reconstructions. A continuous parametric form of the curved line that passes through the vertebrae was created by least square fitting of Fourier series functions. Frenet's formulas then were used to calculate the geometric torsion.

RESULTS

Analysis of geometric torsion associated with 94 major scoliotic curves allowed three basic categories of torsion curve patterns to be identified. Scoliotic spines with multiple major curves are described by a combination of basic torsion patterns, one for each curve.

CONCLUSIONS

A three-dimensional analysis of the spine in terms of geometric torsion has defined three distinct patterns of torsion in a group of scoliotic curves. Geometric torsion had extreme values at the levels of upper and lower vertebrae, but zero or nearly zero values at the levels of the apices. The torsional phenomenon can be unidirectional or bidirectional in both single and double major curves.

Reconstruction of laser-scanned 3D torso topography and stereoradiographical spine and rib-cage geometry in scoliosis

Assessments of scoliosis are routinely done by means of clinical examination and full spinal x-rays. Multiple exposure to ionization radiation, however, can be hazardous to the child and is costly. Here, we explain the use of a noninvasive imaging technique, based on laser optical scanning, for quantifying the three-dimensional (3D) trunk surface topography that can be used to estimate parameters of 3D deformity of the spine. The laser optical scanning system consisted of four BIRIS laser cameras mounted on a ring moving along a vertical axis, producing a topographical mapping of the entire torso. In conjunction with the laser scans, an accurate 3D reconstruction of the spine and rib cage were developed from the digitized x-ray images. Results from 14 scoliotic patients are reported. The digitized surfaces provided the foundation data to start studying concordance of trunk surface asymmetry and spinal shape in idiopathic scoliosis.

Biochemical characterization and surfactant properties of horse allergens

A new allergen from horse dander, Equ c 5 has been purified. Its biochemical and biophysical properties have been characterized and compared with those of Equ c 1, Equ c 2 and Equ c 4. Their molecular masses, determined by mass spectrometry, were 22 kDa for Equ c 1, 16 kDa for Equ c 2, 18.7 kDa for Equ c 4 and 16.7 kDa for Equ c 5. Their pI values were between 3.8 and 5.25. Equ c 2 and Equ c 5 are not glycosylated, while Equ c 4 contains a tri-antennary tri-sialylated N-linked glycan. Linkages of terminal N-acetylneuraminic acid to galactose were: alpha-(2-->6) in Equ c 4, and both alpha-(2-->3) and alpha-(2-->6) in Equ c 1. Oligosaccharide portions of Equ c 1 or Equ c 4 were barely involved in IgE-immunoreactivity. Partial N-terminal sequence of Equ c 4 shares a significant sequence homology with the rat submandibular gland protein A. No matching was found for two internal peptides of Equ c 5. Surfactant properties of horse allergens as well as other proteins were investigated. In contrast to Equ c 2 and Equ c 3, solutions of Equ c 1, Equ c 4 and Equ c 5 significantly lowered the surface tension. Relationship between a property such as this, involving oriented hydrophobic patches of a molecule and allergenicity, is addressed.

Estimation of spinal deformity in scoliosis from torso surface cross sections

STUDY DESIGN

Correlation of torso scan and three-dimensional radiographic data in 65 scans of 40 subjects.

OBJECTIVES

To assess whether full-torso surface laser scan images can be effectively used to estimate spinal deformity with the aid of an artificial neural network.

SUMMARY OF BACKGROUND DATA

Quantification of torso surface asymmetry may aid diagnosis and monitoring of scoliosis and thereby minimize the use of radiographs. Artificial neural networks are computing tools designed to relate input and output data when the form of the relation is unknown.

METHODS

A three-dimensional torso scan taken concurrently with a pair of radiographs was used to generate an integrated three-dimensional model of the spine and torso surface. Sixty-five scan-radiograph pairs were generated during 18 months in 40 patients (Cobb angles 0-58 degrees ): 34 patients with adolescent idiopathic scoliosis and six with juvenile scoliosis. Sixteen (25%) were randomly selected for testing and the remainder (n = 49) used to train the artificial neural network. Contours were cut through the torso model at each vertebral level, and the line joining the centroids of area of the torso contours was generated. Lateral deviations and angles of curvature of this line, and the relative rotations of the principal axes of each contour were computed. Artificial neural network estimations of maximal computer Cobb angle were made.

RESULTS

Torso-spine correlations were generally weak (r < 0.5), although the range of torso rotation related moderately well to the maximal Cobb angle (r = 0.64). Deformity of the torso centroid line was minimal despite significant spinal deformity in the patients studied. Despite these limitations and the small data set, the artificial neural network estimated the maximal Cobb angle within 6 degrees in 63% of the test data set and was able to distinguish a Cobb angle greater than 30 degrees with a sensitivity of 1.0 and specificity of 0.75.

CONCLUSIONS

Neural-network analysis of full-torso scan imaging shows promise to accurately estimate scoliotic spinal deformity in a variety of patients.

Use of Neural Networks to Correlate Spine and Rib Deformity in Scoliosis

Artificial neural networks (ANN's) recognize patterns relating input and output data in a manner analogous to the function of biological neurons. Here, we show that ANN's can predict rib deformity in scoliosis more accurately than regression analysis. ANN's and linear regression models were developed to predict rib rotation from several combinations of input spinal indices including Cobb angle, vertebral rotation, apex location and orientation of the plane of maximal curvature. ANN's averaged 60% correct predictions compared to 34% for regression analysis. This study provides evidence for the utility of artificial neural networks in scoliosis research. These data lend credence to the use of ANN's in future work on the prediction of scoliotic spinal deformity from torso surface data, which would permit assessment of scoliosis severity with minimal use of harmful X-rays.

Immunologic stimulation of mast cells leads to the reversible exposure of phosphatidylserine in the absence of apoptosis

BACKGROUND

Loss of phospholipid asymmetry represents one of the hallmarks of apoptosis and results in the surface exposure of phosphatidylserine (PS) which can be indirectly monitored by the calcium-dependent binding of annexin V.

METHODS AND RESULTS

Here, we provide evidence that the IgE-dependent stimulation of a rat mast cell line, as well as murine and human nontransformed mast cells, leads to the exposure of PS at the plasma membrane. The appearance of PS was quantitatively related to allergic mediator release. Pharmacological agents that prevent stimulus-secretion coupling blocked PS cell surface exposure and calcium ionophore-induced PS appearance, suggesting that it is a direct consequence of exocytosis rather than early signaling events initiated by the aggregation of the high-affinity IgE receptor (FcepsilonRI). The surface exposure of PS in mast cells was reversible even in the continuous presence of stimulus and was not associated with the appearance of apoptotic nuclei, demonstrating that it was independent of physiological cell death.

CONCLUSIONS

In addition to providing a means of monitoring exocytosis at the single cell level, our results indicate that PS externalization in mast cells is not necessarily related to apoptosis but could be an important feature of the degranulation process.

Crystal structure of the allergen Equ c 1. A dimeric lipocalin with restricted IgE-reactive epitopes

The three-dimensional structure of the major horse allergen Equ c 1 has been determined at 2.3 A resolution by x-ray crystallography. Equ c 1 displays the typical fold of lipocalins, a beta-barrel flanked by a C-terminal alpha-helix. The space between the two beta-sheets of the barrel defines an internal cavity that could serve, as in other lipocalins, for the binding and transport of small hydrophobic ligands. Equ c 1 crystallizes in a novel dimeric form, which is distinct from that observed in other lipocalin dimers and corresponds to the functional form of the allergen. Binding studies of point mutants of the allergen with specific monoclonal antibodies raised in mouse and IgE serum from horse allergic patients allowed to identify putative B cell antigenic determinants. In addition, total inhibition of IgE serum recognition by a single specific monoclonal antibody revealed the restricted nature of the IgE binding target on the molecular surface of Equ c 1.

Involvement of antibody-dependent apoptosis in graft rejection

BACKGROUND

Both humoral factors and apoptosis have been recently suggested to play a role in chronic allograft rejection. However, a link between alloantibodies and grafted cell apoptosis has never been proposed. Using the aortic allograft model in the rat, we have previously demonstrated the presence of IgG associated with the disappearance of donor endothelial and medial smooth muscle cells. In the present study, we tested the interaction between recipient allosera, enriched with antibodies by presensitization, and primary culture of cardiovascular cells of donor origin.

METHODS

For this purpose endothelial cells, smooth muscle cells, adventitial fibroblasts, and cardiac myocytes of donor origin were cultured. Binding of alloantisera to these cells was analyzed by flow cytometry. Apoptosis of donor cells was evaluated by Tdt-mediated d' UTP-FITC nick end labeling, 4',6-diamidino-2-phenylindole and DNA ladder techniques. The alloantisera were compared with anti-MHC class I monoclonal antibodies. Finally the colocalization of antibodies and apoptosis was investigated in vivo.

RESULTS

In vitro, alloantisera bind to cardiovascular cells of donor origin. These cells expressed MHC class I but not MHC class II. There was a partial competition between anti-MHC I mouse monoclonal antibody and alloantisera mainly of the IgG isotype. Alloantisera bound to, but did not induce lysis of, donor RBC. Alloantisera induced apoptosis of donor cardiovascular cells as assessed by the typical morphological aspect of the donor cells after 24 hr of incubation. These data were confirmed by the Tdt-mediated d' UTP-FITC nick end labeling positivity of the cells and the fragmentation of the nucleus visualized by 4',6-diamidino-2-phenylindole and DNA ladder techniques. Similar apoptosis was induced by specific monoclonal antibodies directed against the MHC class I of donor cells. Primary culture of similar vascular cells of recipient origin was insensitive to alloantisera directed against donor alloantigens. Finally, in vivo, using allopresentization and aortic allografts, an association of alloantibody binding and endothelial cell apoptosis was observed at day 5, and a similar association with smooth muscle cell apoptosis on day 12 after grafting.

CONCLUSION

These data demonstrate the role of humoral injury in chronic allograft rejection and suggest new therapeutical approaches focused on the induction of resistance to antibody-dependent apoptosis.

A signalling accessory molecule revealed by a new anti-fibroblastoid L cell monoclonal antibody

Fibroblastoid mouse L-cells are widely used in immunological models because when transfected with class II-coding genes they become efficient antigen presenting cells. Little is known, however, about the cell surface markers borne by L-cells and their putative involvement/Interference with the experimental models studied. Rats were immunized against DAP.3 cells (subclone of L-cells) and monoclonal antibodies (mAbs) were prepared. One of them, 4D4, was studied in detail. It recognizes an epitope which is neither cell lineage- nor strain- nor species-restricted since, in addition to DAP.3 cells, it binds, as determined by flow cytometry and immunohistochemistry, to various cells such as CD8+ T cells from thymus, spleen, lymph node or intestinal epithelium, mouse peritoneal B cells and various tissues such as renal, pulmonary or intestinal epithelia. 4D4 mAb immunoprecipitates an undescribed 68 kDa protein. Functionally, this mAb inhibits the IL-2 secretion of a T cell clone in response to its peptide presented by appropriate class II-transfected L-cells and induces a negative selection of double positive CD4+CD8+ thymocytes. Since the 4D4 ligand is found on cells which are submitted to selection (T cells) and on cells which mediate selection (epithelial and antigen presenting cells), we conclude that 4D4 mAb defines a cell surface antigen involved, as an accessory molecule, in a cell selection process.

Antibody-mediated endocytosis of G250 tumor-associated antigen allows targeted gene transfer to human renal cell carcinoma in vitro

Specific gene transfer into targeted tumor cells remains a critical issue for the development of systemic gene therapy protocols. With this end in view, we have tested the possibility of selectively directing genes to tumor cells through the recognition of tumor-associated antigens (TAA). This was approached in vitro on four human renal cell carcinoma (RCC) lines by means of the highly specific mouse G250 monoclonal antibody (mAb) chemically conjugated to a plasmid DNA conveying a reporter activity. This mAb directed to a TAA that is present on 95% of primary RCCs and on 60% of metastatic human RCCs was extensively characterized, including during clinical trials. Epifluorescence microscopy analysis indicated that upon specific binding to G250 TAA, G250 mAb alone or conjugated to plasmid DNA was internalized by an active endocytic process and colocalized with the transferrin concentrated in the late recycling perinuclear compartment. We also observed that both unconjugated G250 mAb or G250 mAb conjugated to plasmid DNA remained in the perinuclear region of the cells for > or = 20 hours and were not rapidly translocated to lysosomes or recycled to the plasma membrane. In contrast, unconjugated plasmid DNA was not internalized. After transfection of G250 TAA-positive RCC lines with G250 mAb conjugated to a plasmid cDNA encoding mouse interleukin-2, a significant and sustained production of mouse interleukin-2 protein was detected from days 5-15 and was abrogated by inhibiting the internalization process. Altogether, our data showed that endocytosis of G250 TAA should be the basis of gene transfer to RCC, suggesting that targeting of TAA capable of internalization may be the basis of new approaches for designing alternative cancer gene therapy procedures.

MHC class II-dependent activation of CD4+ T cell hybridomas by human mast cells through superantigen presentation

Human mast cells (MC) were examined for expression of MHC class II antigens and for their ability to activate CD4+ T cell hybridomas through presentation of superantigen (SAg). HMC-1, a leukemic immature MC line expressing class II Ags, was shown to efficiently present the staphylococcal enterotoxin B (SEB) SAg to responding T cell hybridoma on treatment with interferon-gamma (IFN-gamma), which up-regulated class II molecules. The study was then extended to human normal MC. Almost pure (>99%) cord blood-derived MC (CBMC) were shown to express class II Ags (HLA-DR and HLA-DQ) and CD80, which were up-regulated by IFN-gamma treatment and, to a lesser extent, by interleukin-4 (IL-4) and granulocyte-macrophage colony-stimulating factor (GM-CSF). CBMC directly activated CD4+ T cell hybridomas through presentation of SEB and TSST1 SAgs. The production of IL-2 required a cell-to-cell contact between T cells and CBMC and it was inhibited by anti-class II antibodies. Furthermore, an additional pretreatment of CBMC by IFN-gamma or GM-CSF or IL-4 had no effect on their presenting efficiency. This previously unknown function of human MC, i.e., MHC class II-dependent activation of CD4+ T cells, may be critical in subsequent cellular activation events because colocalization of mast and T cells is frequently observed at sites of antigen entry.

[Prognostic factors in malignant melanoma of the conjunctiva. An anatomo-clinical study of 56 patients]

We have reviewed a serie of 56 patients treated in our Institute for malignant melanoma of the conjunctiva between 1980 and 1992. We selected cases where histology had been reviewed.

PATIENTS AND METHOD

The median follow up is 96 months. The age varies from 13 to 88 years with a mean age of 56 years. There were 22 men and 34 females. In 29 cases (51%) the melanoma appeared de novo, ten cases (17%) it derived from a naevus and in 14 cases (25%) on a precancerous melanosis. The tumour was localized at the limbus and bulbar conjunctiva in 57% of cases. The mean diameter was 6.1 mm and the mean thickness was 2.3 mm. The treatment consisted in surgical excision of the tumour followed by external beam radiothérapy in 49 cases. Histological examination showed invasion of the chorion in 44 cases (78%) and of the sclera in 6 cases (1%).

RESULTS

38 patients are alive and 29 without disease. 2 with disease, 7 lost follow-up. 18 patients died (32%) and among them 14 (25%) died of metastatic disease. 22 patients (39%) have presented local recurrence and among them 10 have had multiple recurrences. The mean delay for recurrence was 56 months. The overall survival was 77% at 5 years and 64% at 10 years. Tumours appeared de novo have a worse prognosis. If we consider the localization tumour located at the limbus or on bulbar conjunctiva have less metastasis.

CONCLUSION

Malignant melanoma of conjunctiva is a tumour that can frequently recur. Metastasis are not infrequent and follow up must be prolonged.

Targeted transfection of the IL-3 gene into primary human hematopoietic progenitor cells through the c-kit receptor

We recently showed that an antibody-mediated gene transfer procedure termed antifection can be used for targeted gene delivery into lymphoid cells in vitro and in vivo. We here report that antifection also is effective for targeted gene transfer to immature hematopoietic cells. A human IL3-expressing plasmid was chemically linked to an anti-human CD117 antibody. Delivery of the IL3 plasmid into IL-3-dependent myeloid TF-1 cells (bearing the CD117 antigen) was specific and resulted in the transient proliferation of the targeted cells in the absence of exogenous IL-3. Transfection of primary human CD34+ hematopoietic stem/progenitor cells led to transient production of IL-3 and transient proliferation of the target cells. Interestingly, by using a semisolid progenitor cell assay, we found that transfected primary CD34+ cells were able to generate normal numbers of cell colonies in the absence of exogenous IL-3. Polymerase chain reaction analysis confirmed the presence and expression of the IL-3 transgene in the progenitor-derived colonies. In conclusion, our data show that CD117 is a suitable cell surface target to specifically transfer gene by antifection into primary CD34+ cells and that delivery of IL-3 gene in these cells resulted in the expression of a functional IL-3 able to support cell growth in absence of exogenous cytokine. Thus, antifection may provide new therapeutic modality relying on the transient production of appropriate growth factors acting via autocrine and/or paracrine mechanisms.

[Unilateral retinoblastomas with late bilateralization. Three case reports]

Three cases of unilateral retinoblastoma with late bilateralization are presented in this study. The rare occurrence of this event underlines the need for prolonged follow-up in the fellow-eye, even in the absence of familial retinoblastoma. In these three cases, the first affected eye was enucleated after a diagnosis made at three months, sixteen months and three years of age. New tumors appeared in the second eye when the children were sixteen years old in one case and five years old in two cases.

Anemia is associated with lower local-regional control and survival after radiation therapy for head and neck cancer: a prospective study

PURPOSE

To evaluate the prognostic value of anemia in squamous cell carcinomas in the head and neck treated with curative radiation therapy alone.

MATERIALS AND METHODS

In a prospective study, the hemoglobin level was measured prior to radiation therapy in 217 patients (188 [87%] men and 29 [13%] women) with cancer of the oral cavity (n = 61 [28%]), oropharynx (n = 53 [24%]), hypopharynx (n = 21 [10%]), and larynx (n = 82 [38%]). Anemia, defined as hemoglobin level below 13.5 g/dL in men and below 12.0 g/dL in women, was diagnosed in 58 (31%) of the men and five (17%) of the women. Median follow-up was 29 months (range, 2-63 months).

RESULTS

The 2-year actuarial probability of local-regional control was 69% (95% confidence interval, 63%, 76%). Multivariate analysis showed the relative risk of failure of local-regional control to increase for stage T3 and T4 tumors (1.8 [95% confidence interval, 1.1, 3.1]), stage N3 nodes (3.6 [95% confidence interval, 1.8, 7.1]), weight loss (2.2 [95% confidence interval, 1.3, 4.0]), and anemia (1.6 [95% confidence interval, 1.0-2.7]). The relative risk of death increased for stage T3 and T4 tumors (2.5 [95% confidence interval, 1.4, 4.3]), N3 nodes (4.0 [95% confidence interval, 1.0, 7.9]), oral cavity tumors (2.0 [95% confidence interval, 1.2, 3.2]), male sex (4.1 [95% confidence interval, 1.3, 13.1]), weight loss (2.2 [95% confidence interval, 1.3, 3.7]), and anemia (1.7 [95% confidence interval, 1.03, 2.7]).

CONCLUSION

Moderate anemia appeared to be an independent prognostic factor in squamous cell carcinoma of the head and neck treated with radiation therapy alone.

Mouse bone marrow-derived mast cells and mast cell lines constitutively produce B cell growth and differentiation activities

The present report describes a novel function of mast cells that consists of a B cell growth activity. The B cell response occurred without any stimulation or preactivation of mast cells. A small number of mast cells was required, since mast cell/B cell ratios as low as 1/100 to 1/10,000 lead to effective B cell activation. Mast cell-dependent B cell activation resulted, within 48 h of incubation, in blast formation, proliferation, and IgM production. Both low and high density B cells were responsive to mast cells. Supernatants from unstimulated mast cells could also activate B cells, suggesting that a B cell-stimulating activity (MC-BSA) is mediated by a soluble factor(s). The addition of anti-IL-4 or anti-IL-6 mAbs or even proteases to the mast cell-derived supernatants did not alter B cell activation. However, treatment of mast cells with mitomycin C or actinomycin D, or paraformaldehyde fixation totally abrogated MC-BSA. Fractionation of mast cell supernatant by gel filtration chromatography resulted in four peaks, ranging from > 200 to 15 kDa, all of which were biologically active on B cells. Because mast cells are known to continuously release proteoglycans, MC-BSA was subjected to chondroitinase and heparinase treatment, but no significant inhibition of B cell activation was obtained. This direct T cell-independent stimulatory effect of mast cells on B cells could account for a mechanism by which plasma cells are continuously produced in lymphoid organs and particularly in bone marrow.

Mouse bone marrow-derived mast cells and mast cell lines constitutively produce B cell growth and differentiation activities

The present report describes a novel function of mast cells that consists of a B cell growth activity. The B cell response occurred without any stimulation or preactivation of mast cells. A small number of mast cells was required, since mast cell/B cell ratios as low as 1/100 to 1/10,000 lead to effective B cell activation. Mast cell-dependent B cell activation resulted, within 48 h of incubation, in blast formation, proliferation, and IgM production. Both low and high density B cells were responsive to mast cells. Supernatants from unstimulated mast cells could also activate B cells, suggesting that a B cell-stimulating activity (MC-BSA) is mediated by a soluble factor(s). The addition of anti-IL-4 or anti-IL-6 mAbs or even proteases to the mast cell-derived supernatants did not alter B cell activation. However, treatment of mast cells with mitomycin C or actinomycin D, or paraformaldehyde fixation totally abrogated MC-BSA. Fractionation of mast cell supernatant by gel filtration chromatography resulted in four peaks, ranging from &gt; 200 to 15 kDa, all of which were biologically active on B cells. Because mast cells are known to continuously release proteoglycans, MC-BSA was subjected to chondroitinase and heparinase treatment, but no significant inhibition of B cell activation was obtained. This direct T cell-independent stimulatory effect of mast cells on B cells could account for a mechanism by which plasma cells are continuously produced in lymphoid organs and particularly in bone marrow.

Antifection: an antibody-mediated method to introduce genes into lymphoid cells in vitro and in vivo

We have developed a simple, safe and versatile method, termed antifection, by which antibodies are used as delivery vehicles to introduce genes into cells expressing specific surface antigens. Antibodies directed against CD3, CD34 or surface immunoglobulins were covalently coupled to plasmids containing marker genes (neoR, beta-galactosidase). Such conjugates were used in vitro and/or in vivo to antifect (transfect using antifection) cells bearing the respective targeted epitope on either normal splenic B lymphocytes or lymphoid-related cell lines. In these conditions the expression of the protein encoded by the marker gene was readily detected. Antifection is a method of delivering genes through a physiological cellular pathway, receptor-mediated endocytosis, into specific cell types, and thus may be considered as an alternative for gene therapy strategy.

Sequential immunological targeting of chronic experimental arterial allograft

Arterial wall is the main site involved in the chronic rejection process. The rat aortic allograft model was used here to characterize and describe the sequential evolution of the different targets and effectors of arterial wall immunological injury and response during arterial allograft rejection. Rat abdominal aortae were isografted or allografted from Brown-Norway to Lewis rats. Endothelial and smooth muscle cell injury and humoral and cellular immunological effectors were characterized from 0 to 60 days after transplantation using a battery of specific antibodies. The intimal proliferative response was also characterized over this time. Isografted Brown-Norway aorta adventitia had very few cellular components, which suggests that donor adventitia would be poorly antigenic in allografts. In contrast, allograft adventitia was the site of a major inflammatory cell invasion in which the expression of an adhesion molecule by colonizing capillary endothelial cells could play a main role. This adventitial infiltration continued as long as medial smooth muscle persisted. The luminal endothelial cells disappeared early, probably associated with macrophage margination. In contrast, medial smooth muscle cell disappearance occurred later and was specifically targeted by immunoglobulins. Intimal proliferation was the most delayed phenomenon, involving both inflammatory cell infiltration at an early stage and later myofibroblastic proliferation, and could be related to the specific expression of growth factors in this layer. The rat aortic allograft model appeared useful for characterizing specific targets and effectors of chronic arterial graft rejection, demonstrating an early stage of endothelial injury and the presence of immunoglobulins involved in chronic medial smooth muscle cell injury.

Mercuric chloride-induced programmed cell death of a murine T cell hybridoma. II. Opposite effect of interleukin-2 and interleukin-4

In susceptible animals evidence is accumulating for a primary role for Th2 cells in the course of HgCl2-induced autoimmunity, and for a contribution of Th1 cells in the self-regulated phase of this disease. We have reported that incubation of 2B4.11 T cell hybridoma with HgCl2 induced programmed cell death. This paper shows that recombinant IL-2 significantly diminished HgCl2-induced 2B4.11 cell death. Although no effect was observed upon incubation with exogenous IL-4, we observed a significant protection by adding an anti-IL-4 monoclonal antibody to the culture. Accordingly, by RT-PCR we found the presence of IL-2 receptor-encoding mRNA, and by cytofluorometry, the expression of the protein was detected only after exposure to HgCl2. Moreover, upon HgCl2 treatment, 2B4.11 cells were induced to produce IL-4. Altogether these findings showed that cytokine environment, IL-2, IL-4 otherwise defining the Th1/Th2 dichotomy, in conjunction with a chemical may differentially influence the fate of cell populations, death or survival.

Mercuric chloride-induced programmed cell death of a murine T cell hybridoma. I. Effect of the proto-oncogene Bcl-2

Mercuric chloride (HgCl2) as well as several drugs can induce T cell activation leading to systemic immune-mediated diseases in genetically susceptible individuals or rodents. T cell hybridomas represent a well-characterized model system for in vivo mechanisms of various stimuli-induced cell death. The cellular response to HgCl2 was examined using various T cell lines and particularly the murine T cell hybridoma 2B4.11. Exposure to HgCl2 induced both necrosis and apoptosis in a dose- and time-dependent way as demonstrated by DNA fragmentation analysis, flow cytometry of the whole cells and of isolated nuclei, and morphological examination. HgCl2-induced cell death was partly inhibited by cycloheximide. The expression of human Bcl-2 in 2B4.11 cells after transfection significantly prevented HgCl2-induced cell death but did not affect the susceptibility to apoptosis induced by an anti-CD3 epsilon mAb. Subcytotoxic doses of HgCl2 enhanced metabolic activity of Bcl-2 transfectants in contrast with mock-transfected cell line. Thus, we conclude that apoptosis is part of the cell death process induced by HgCl2 and that the ability of Bcl-2 to prevent the death of one particular cell line is stimulus-dependent suggesting the existence of different pathways leading to cell death.

Anti-histone autoantibodies react specifically with the B cell surface

In an attempt to induce an immune response against Mls-1a antigens by immunizing C57B1/6 mouse (Mls-1b) with purified B cells from DBA/2 mouse (Mls-1a), we generated a panel of monoclonal antibodies from which the 5B9.6 mAb, taken as a representative antibody, was thoroughly investigated. This antibody specifically reacts with B cells from all mouse strains studied including C57Bl/6 mice as shown by FACS analysis of double-antibody labelled spleen cells. Using enzyme immunoassays and immunoprecipitation techniques, 5B9.6 mAb was found to be specific for histones. Amino acid sequence analysis of a peptide derived from a 5B9.6-immunoprecipitated polypeptide from DBA/2 B cells showed a 100% homology with a sequence within H2B histones. Furthermore, 5B9.6 mAb was able to interact with the cell surface of 7OZ/3 cell line, known as a typical pre-B cell line. The presence of histones can be modulated on the surface of 7OZ/3 cells since this antigen was upregulated after exposure of these cells to a cocktail of IL-1 and cAMP. Finally, 5B9.6 mAb was shown to interact with freshly isolated B cells from human peripheral blood.

Biased VH gene expression in murine CD5 B cells results from age-dependent cellular selection

Flow cytometry-purified, peritoneal and splenic CD5+ and CD5- B cells from neonatal and adult C57BL/6 mice were studied for expression of VH and Vx gene families in RNA colony blot assays, and for frequencies of clones secreting antibodies to bromelain-treated mouse red blood cells (BrMRBC), single-stranded DNA, trimethyl ammonium and bovine gamma-globulin, by limiting dilution. The results show few overall differences between the two B cell subsets, which both manifest ontogenic D-proximal VH preferences that are lost with age. Biased VH11 expression in CD5 B cells is high in adult peritoneum and spleen but absent in newborns. It only partly correlates with the selection of anti-BrMRBC reactivity, which is considerably higher in peritoneum than in spleen. No particular Vx bias was observed in any of the populations studied with the possible exception of Vx22 in peritoneal CD5+ B cells. We conclude that the antibody repertoire expressed by peritoneal CD5+ B cells of adult mice is not the result of a genetic program, but rather the consequence of local, age-dependent cellular selection mechanisms.

Cerebrovascular accidents in infective endocarditis: role of anticoagulation

Anticoagulation is still a matter of debate in infective endocarditis, since it can increase the risk of complications, mostly neurological. In our series of 269 patients with native valve endocarditis studied between 1970 and 1982, 35 were anticoagulated. We observed 14 patients with brain infarcts, of whom five died, and 12 patients with cerebromeningeal or brain haemorrhage of whom six died. In a similar series of 63 patients with prosthetic valve endocarditis, all of whom were on anticoagulation and were studied between 1972 and 1987, we observed five patients with brain infarcts, three of whom died, and two patients with brain haemorrhage, one of whom died. The frequency of cerebrovascular accident (CVA) was similar for both groups (11.1% in prosthetic endocarditis vs 11.5% in native valve endocarditis, P = ns), as was mortality rate (57% vs 48.4%, P = ns). CVA are significantly more frequent among anticoagulated patients (19/94 vs 19/238: P less than 0.01), but the mortality rate in CVA is similar for anticoagulated and non-anticoagulated patients (11/19 vs 8/19: P = ns). The indications for anticoagulation in infective endocarditis remain similar to those in valvular heart disease. In patients with infective endocarditis, anticoagulation with heparin should be maintained whenever a brain infarct is present, unless it is large and/or haemorrhagic.

All VH11 genes expressed in peritoneal lymphocytes encode anti-bromelain-treated mouse red blood cell autoantibodies but other VH gene families contribute to this specificity

We have studied the relationship between B cell reactivity to bromelain-treated autologous mouse erythrocytes (BrMRBC) and expression of the VH11 gene family in splenic, peritoneal and pleuropericardial cell populations from normal C57BL/6 mice. B lymphocytes producing antibodies to BrMRBC were selectively enriched or depleted from normal populations by rosette formation with BrMRBC, followed by centrifugation over density gradients. This selection method, based on the presence of functional receptors (membrane IgM), is harmless for the cells and allowed subsequent cloning in agar (colony-forming unit-B). The utilization of the 10 VH gene families was then scored in mRNA colony blot assays. The analysis of greater than 650 anti-BrMRBC clones and greater than 350 VH11-expressing colonies indicates that about half of those antibody reactivities are encoded by VH11 genes. Furthermore, it appears that all VH11-expressing B cells in the peritoneal cavity produce anti-BrMRBC antibodies.

Ontogenic development of autoantibody repertoires in spleen and peritoneal cavity of normal mice: examples of T cell-dependent and -independent reactivities

The ontogenic development of B cell clonal precursors (BCP) reactive to bromelain-treated, syngeneic erythrocytes (BrMRC) and to single-stranded DNA has been studied by limiting dilution of both spleen and peritoneal cells. It was found that the frequency of anti-BrMRC BCP in the spleen is very low up to 4 weeks of age and slowly increases thereafter, to reach adult levels by 6-10 weeks. In the peritoneal cavity, no such BCP can be found before 2 weeks, but they occur at a very high frequency already by 3 weeks of age. Injection of adult, normal syngeneic T cells at birth has no apparent effect on the representation of anti-BrMRC BCP in the peritoneal cavity, but brings these to adult levels or even higher in the spleen already at 3 weeks of age. Accordingly, adult athymic (nude) mice contain normal frequencies of BrMRC-specific BCP in the peritoneal cavity but are devoid of such clones in the spleen. In contrast, the frequency of anti-DNA BCP is very high throughout postnatal development in both spleen and peritoneal cavity, of normal and athymic mice, in both resting and naturally activated splenic B cell compartments, and it is independent of T cell transfers into nude animals. These results indicate the role of T cells in the establishment of some clonal specificities in the adult, splenic autoreactive B cell repertoire.

Immunoglobulin VH gene expression in Ly-1+ and conventional B lymphocytes

Lymphocyte populations in which Ly-1 B cells are differentially represented were studied for the expression of ten VH gene families, either by an RNA colony blot assay or by in situ hybridization of single cells, in BALB/c and C57BL/6 mice. The comparisons of cells from lymph nodes, Peyer's patches and adult spleen (poor in Ly-1 B cells) with cells from peritoneal cavity and neonatal spleen (rich in Ly-1 B cells) were confirmed by the analysis of adult peritoneal Ly-1- and Ly-1+ B cells sorted on the fluorescence-activated cell sorter. The results indicate that the peritoneal Ly-1+ B subset uses the whole spectrum of known VH gene families, and shows a preferential utilization of CP12 VH genes, most likely as a result of a selective process during life.

Expression of VH11-gene family in hybridoma collections from peritoneum and spleen: differential correlation with BrMRBC reactivity

Hybridoma collections from spleen or peritoneal cells of newborn or adult individuals were screened by RNA hybridization for expression of the VH11-gene family using a V-region probe VCP12, which encodes anti-BrMRBC antibodies. No VH11 expression was observed in hybridomas derived from newborn spleen cells in either BALB/c, NZB or (CBA/N x BALB/c) F1 mice (0/93). Adult NZB and BALB/c spleen cell collections contained only one hybridoma expressing VH11 (1/242). Interestingly, however, the VH11-positive hybridoma showed no anti-BrMRBC reactivity, while one anti-BrMRBC clone in the same collection expressed a Q52 VH gene. In contrast, hybridomas derived from peritoneal cells showed an absolute correlation between expression of VH11 genes and anti-BrMRBC reactivity (15/32). The high expression in the peritoneal cavity of such cells is likely the result of local positive selection.

Immunochemical studies of polyspecific natural autoantibodies: charge, lipid reactivity, Fab'2 fragments activity and complement fixation

Polyspecific natural autoantibodies (NAAb) are antibodies present in normal unimmunized animals and are able to react with very dissimilar antigens (Ag). To better delineate the characteristics of polyspecificity, we subjected monoclonal NAAb to four different immunochemical studies: (1) Two-dimensional gel electrophoresis performed on eight NAAb did not reveal any obvious relationship between charge and antigen specificities; (2) NAAb widely polyspecific on proteins and nucleic acid were reactive with lipids bearing either phosphate, sulfate or carboxyl polar groups; (3) pepsin digestion of polyspecific IgM NAAb yielded Fab'2 fragments which maintained their multireactivities, but exhibited a decrease in reactivity as compared to that seen with monospecific mAb (induced); (4) two different assays were used to analyse the complement fixation ability of IgM NAAb. While very weak or no complement fixation was observed with a classical complement fixation test (fluid phase), when a complement enzyme immunoassay was used where Ag is immobilized on a solid phase, polyspecific NAAb fixed reproducible and easily detectable amounts of complement.

Comparative analysis of natural antibody specificities among hybridomas originating from spleen and peritoneal cavity of adult NZB and BALB/c mice

A preliminary experiment showed that the supernatants of in vitro cultured peritoneal cells (rich in Ly-1 B cell subset shown to secrete most IgM autoantibodies against bromelain-treated mouse red blood cells (BrMRBC) and DNA) from different mouse strains did not contain any significant antibody activity against DNA and cytoskeleton proteins, although the presence of anti-BrMRBC antibodies was clearly evident. Therefore, we investigated comparative natural antibody (NAb) specificities against an antigen panel (DNA, cytoskeleton proteins, IgG, bovine serum albumin (BSA), BrMRBC, trinitrophenyl (TNP), and trimethylammonium (TMA) haptens) among Ig-secreting hybridoma collections from the splenic (158) and peritoneal (230) immune compartments of autoimmune New Zealand black (NZB) and lipopolysaccharide (LPS)-stimulated BALB/c mice. The data showed: (i) isotypic restriction (mu and gamma 3 only), predominance of TMA ion-reactive (including BrMRBC) but negligible anti-DNA-reactive antibody specificities, and lack of simultaneous polyspecific widespread reactivity (i.e. at least four or more antigens) against DNA and cytoskeleton proteins in the peritoneal cavity; (ii) predominance of simultaneous widespread polyspecific reactivity against DNA and cytoskeleton proteins but negligible or no TMA hapten-reactive antibody specificities in the spleen. These observations reflect certain differences in the B cell repertoire of peritoneal cavity (rich in Ly-1 B cells) compared with spleen. The NAb against BrMRBC and those reactive with DNA and cytoskeleton proteins, which have been suggested to be secreted by the Ly-1 B cell subset, are distinguishable on the basis of the presence of separate recurrent idiotypes and preferential localization of B lymphocytes directed against these autoantigens.

[Microdetermination of pyrazinamide and its metabolites (pyrazinoic acid, 5-hydroxypyrazinoic acid, 5-hydroxypyrazinamide and pyrazinuric acid) in plasma and urine with liquid chromatography]

The method reported here for determining pyrazinamide and its metabolites (2-pyrazinoic acid, 5-hydroxypyrazinamide, 5-hydroxypyrazinoic acid and pyrazinuric acid) consists of diluting urine or acid deproteinisation of serum followed by chromatography on a cation-exchange column. The column length and the detection system (ultraviolet or fluorimetry) allow for a very good separation of the different compounds; the sensitivity of the method makes it suitable for pharmacokinetic studies.

Age-related natural antibody specificities among hybridoma clones originating from NZB spleen

In the studies presented here, age-related natural antibody specificities have been investigated in the autoimmune NZB mouse strain by cell fusion. The monoclonal immunoglobulins (MIg) secreted by productive hybridoma clones were examined for their antibody activities against a panel of antigens, including single- and double-stranded DNA, actin, tubulin, myosin, bromelain-treated mouse red blood cells (BrMRBC) and TNP-BSA, employing both direct and competitive enzyme immunoassays. The antibody specificities against this panel of antigens were strikingly frequent among hybridoma clones from neonatal NZB (49%) mice, compared to normal BALB/c neonates (8.8%) shown earlier. Among neonatal hybridomas with known antigen reactivities, 73% of the clones exhibited polyspecific binding. In contrast, the majority of hybridomas from 5- and 7-month-old NZB spleen reacted monospecifically (76%) with the antigens tested. Such a characteristic reactivity pattern reflects an age-related evolution of B-cell repertoire expression. Unlike normal BALB/c mice, a high frequency of monospecific TNP-hapten-reactive clones (75%) was noticed among hybridomas of known antigen reactivities from 5- and 7-month-old NZB-strain mice, an age when autoimmune haemolytic anaemia sets in. In conclusion, an elevated frequency of autoreactive clones among neonates (49%) and an aberrant expression of TNP-reactive clones in adults seem to be an outward signal of certain discrepancies at the level of B-cell repertoire expression in autoimmune NZB-strain mice.

Novel V genes encode virtually identical variable regions of six murine monoclonal anti-bromelain-treated red blood cell autoantibodies

The variable (V) region sequences of six immunoglobulin M (IgM, kappa) monoclonal autoantibodies that recognize bromelinized isologous red blood cells, obtained by fusions of peritoneal cells from NZB or CBA/J nonimmunized mice with BALB/c myeloma cells, were determined by direct mRNA sequencing. The V regions of the light chains (VL) are almost identical with one another, as are the V regions of the heavy chains (VH), which, however, differ by six linked-base substitutions, depending on the strain of mice producing the autoantibodies. Such variations may reflect allelic differences. The VH segments determined have no obvious correspondence to any VH genes identified so far. They may belong to the small VH group 4, where 73% homology, at the most, can be calculated at the protein level for codons 1 to 94. Alternatively, the VH regions may be members of a new group of VH sequences not previously found. The V kappa regions appear closely homologous to members of the V kappa-9 subgroup of myeloma proteins of unknown antigen-binding specificity. The joining segments, J kappa and JH, used by the autoantibodies investigated, originate from the J kappa 2 and JH1 germ-line gene segments, respectively. The nine base-long diversity segments, D, derive from one member of the germ-line D gene SP2 family.