The diversity of antigen-specific TCR repertoires reflects the relative complexity of epitopes recognized

Antigen-selected T cell receptor (TCR) repertoires vary in complexity from very limited to extremely diverse. We have previously characterized two different CD8 T cell responses, which are restricted by the same mouse major histocompatibility complex (MHC) class I molecule, H-2 Kd. The TCR repertoire in the response against a determinant from Plasmodium berghei circumsporozoite protein (PbCS; region 252-260) is very diverse, whereas TCRs expressed by clones specific for a determinant in region 170-179 of HLA-CW3 (human) MHC class I molecule show relatively limited structural diversity. We had already demonstrated that cytolytic T lymphocyte (CTL) clones specific for the PbCS peptide display diverse patterns of antigen recognition when tested with a series of single Ala-substituted PbCS peptides or mutant. H-2 Kd molecules. We now show that CW3-specific CTL clones display much less diverse patterns of recognition. Our earlier functional studies with synthetic peptide variants suggested that the optimal peptides recognized were 9 (or 8) residues long for PbCS and 10 residues long for CW3. We now present more direct evidence that the natural CW3 ligand is indeed a 10-mer. Our functional data together with molecular modeling suggest that the limited TCR repertoire selected during the CW3 response is not due to a paucity of available epitopes displayed at the surface of the CW3 peptide/Kd complex. We discuss other factors, such as the expression of similar self MHC peptide sequences, that might be involved in trimming this TCR repertoire.

Synthetic polypeptides corresponding to the non-repeat regions from the circumsporozoite protein of Plasmodium falciparum: recognition by human T-cells and immunogenicity in owl monkeys

Synthetic polypeptides encompassing the non-repeated regions of the circumsporozoite protein (CSP) of Plasmodium falciparum are very immunogenic in mice and are recognized by sera from donors living in regions where malaria is endemic, both in Africa and South America. Long polypeptides, encompassing the N- or C-terminal regions, have now been used to demonstrate peptide-specific T cells in donors living in an endemic area of Colombia. Although the N-terminal peptide (22-125) was recognized almost exclusively by donors from the endemic area, the patterns of recognition of the C-terminal peptide (289-390) in donors from endemic and non-endemic areas were similar and like the pattern with smaller peptides. The availability of the long polypeptides made it possible to compare T-cell responses to the non-repeated regions of the CSP with the presence of peptide-specific antibodies. No correlation was found and no antibodies were detected in donors from non-endemic regions. The long polypeptides also elicited strong antibody and T-cell responses in owl monkeys (Aotus lemurinus). The antibodies generated against the synthetic peptides in such monkeys also recognized sporozoites, the natural infective form of the parasite. The results emphasise the potential of the peptides tested as malaria-vaccine candidates. Not only are they recognized by humans at both the B- and T-cell level but they also elicit strong responses in monkeys and encompass several distinct T-cell epitopes, thus overcoming the limitations of specific, major-histocompatibility-complex restriction.

Molecular mechanisms of platelet adhesion and activation

When a blood vessel is injured, control of bleeding starts with the rapid adhesion of circulating platelets to the site of damage. Within seconds, the adhered platelets are activated, secrete the contents of storage organelles, spread out over the damaged area and recruit more platelets to the developing thrombus. However, if this same process occurs in a diseased, sclerotic or occluded vessel, the resulting platelet thrombus may break away and block the coronary artery, causing a heart attack, or restrict blood supply to the brain, causing a stroke. The glycoprotein (GP) Ib-IX-V complex, a member of the leucine-rich protein family, is a constitutive platelet membrane receptor for von Willebrand Factor (vWF), a multimeric adhesive glycoprotein found in the matrix underlying the endothelial cell lining of the blood vessel wall and in the plasma. Binding of vWF to the GP. Ib-IX-V complex regulates adhesion of platelets to the subendothelium at high shear flow, and initiates signal transduction leading to platelet activation. The GP Ib-IX-V complex also constitutes a binding site for alpha-thrombin, an interaction that facilitates thrombin-dependent platelet activation. This review will focus on recent detailed analysis of the GP Ib-IX-V complex and vWF that has identified discrete amino acid sequences that mediate their interaction. An anionic/sulfated tyrosine sequence of the GP Ib alpha-chain that is critical for binding of the GP Ib-IX-V complex to both vWF and alpha-thrombin is analogous to sulfated anionic amino acid sequences mediating interactions of other adhesive proteins, including P-selectin binding to PSGL-1 and Factor VIII binding to vWF.

[Detection of low-avidity IgG antibodies in the diagnosis of primary acute infection by hepatitis C virus]

BACKGROUND

Differential diagnosis of the acute primary infection by hepatitis C virus (HCV) from reactivations and reinfections presents specific problems, especially among patients with impaired humoral immunity. the IgG avidity assay might contribute to resolve these problems.

METHODS

A simple modification of a commercial enzyme immunoassay, allowing evaluation of the avidity of IgG antibody to HCV, was developed and evaluated on a part of 37 serum samples from 14 patients with acute primary infection or reinfection by HCV and 12 samples from 12 seropositive patients lacking evidence of acute infection Eight of the former 14 had impaired ability for antibody response.

RESULTS

The method rendered high percentages of reduction of the antibody signal in samples from acute primary infections taken within two months from onset and significantly lower percentages in samples from reinfections or patients without evidence of acute infection (mean value: 90 degrees C Vs 43% and 25%, respectively. The mean duration of the low-avidity IgG antibody was around six months, but showed wide variations depending on the patient.

CONCLUSIONS

Detection of low-avidity IgG antibody to HCV is easy to perform and may help the study of the HCV infection in some patients. Every method should, however, be carefully validated before using with diagnostic purposes.

p53 exon 5 mutations as a prognostic indicator of shortened survival in non-small-cell lung cancer

Inactivation of the tumour-suppressor gene p53 has been described as one of the most common molecular changes found in lung tumours. Our purpose was to study the prognostic value of p53 alterations and to determine whether some specific mutation type in the p53 gene could be associated with poor clinical evolution in non-small-cell lung cancer (NSCLC) patients. To this end, we studied 81 resected primary NSCLCs in order to detect p53 alterations. p53 protein accumulation was analysed using immunohistochemistry methods; p53 gene mutations in exons 5-9 were studied using polymerase chain reaction-single-strand conformation polymorphism and sequencing techniques. p53 protein was immunodetected in 46.9% of lung carcinomas and 44.7% of p53-immunopositive tumours showed p53 mutations. Survival analysis was performed on 62 patients. No survival differences were found for patients with or without p53 immunopositivity. A shorter survival was found in patients with underlying p53 gene mutations, mainly in patients with squamous cell lung tumours; the worst prognosis was found when mutations were located in exon 5 (P = 0.007). In conclusion, the location of p53 mutations might be considered as a prognostic indicator for the evaluation of poor clinical evolution in NSCLC patients.

Typing of hepatitis C virus antibody with specific peptides in seropositive blood donors and comparison with genotyping of viral RNA

BACKGROUND AND OBJECTIVES

Serotyping of antibody to hepatitis C virus (anti-HCV) with specific peptides has been developed as an alternate method for typing HCV infections. The method does not require a prior amplification of viral RNA sequences from the sample. Identification of the viral genotype may be relevant for prognosis and clinical management.

MATERIALS AND METHODS

We used a previously described HCV serotyping assay (RIBA HCV Serotype SIA kit, Chiron Corp.) to investigate the serotype in 191 samples from blood donors selected for anti-HCV patterns (positive and indeterminate), ALT levels, and the presence or absence of viral RNA. The serotypes were compared with the genotypes obtained from typing the 5'-noncoding region of the viral RNA in 82 viremic samples.

RESULTS

We were able to obtain the viral serotype in 85% (114/134) of samples positive for anti-HCV but in only 3.5% (2/57) of the indeterminates. Lack of anti-NS4 in the sample was significantly associated with both untypable results and the presence of HCV serotypes other than serotype 1. The overall correlation with genotyping was 78% (64/82), rising to 95.5% (64/67) if only samples that could be both genotyped and serotyped were considered. The assay was easy to perform, gave reactivity patterns easy to interpret, and performed with high proficiency on anti-HCV-positive samples lacking detectable levels of viral RNA.

CONCLUSIONS

This is a practical and useful method for typing HCV infections in the clinical setting. The poor ability of the Core peptides to give the serotype in samples lacking anti-NS4 and the lack of specific peptides to recognize HCV types other than 1, 2, and 3 are, however, some aspects of the method that need improvement in the future.

Conformational studies of a short linear peptide corresponding to a major conserved neutralizing epitope of human respiratory syncytial virus fusion glycoprotein

The conformational properties of a 21-residue peptide, corresponding to amino acids 255 to 275 (F255-275) of the human respiratory syncytial virus fusion (F) glycoprotein have been studied by CD and nmr spectroscopy. This peptide includes residues 262, 268, and 272 of the F polypeptide that are essential for integrity of most epitopes that mapped into a major antigenic site of the F molecule. CD data indicate that F255-275 adopts a random coil conformation in aqueous solution at low peptide concentrations. However, as the concentration of peptide is increased, a higher percentage of peptide molecules adopts an organized structure. This effect can be more easily observed when trifluoroethanol (30%) is added to peptide solutions, giving rise to CD spectra that resemble those of alpha-helix structures. These conformational changes were confirmed by nmr spectroscopy. The nuclear Overhauser effects observed in 30% trifluoroethanol/ water together with the conformational H alpha chemical shift data allowed us to propose a structural model of helix-loop-helix for the peptide in solution. In addition, these helical regions contain the amino acid residues essential for epitope integrity in the native F molecule. These results give new insights into the antigenic structure of the respiratory syncytical virus F glycoprotein.

Binding of a novel 50-kilodalton alboaggregin from Trimeresurus albolabris and related viper venom proteins to the platelet membrane glycoprotein Ib-IX-V complex. Effect on platelet aggregation and glycoprotein Ib-mediated platelet activation

Binding of the multimeric adhesive glycoprotein, von Willebrand Factor (vWF), to the platelet membrane glycoprotein (GP) Ib-IX-V complex mediates platelet adhesion and initiates signal transduction leading to platelet activation. Recently described viper venom proteins that bind to the GP Ib alpha-chain and inhibit vWF binding provide novel probes for studying receptor function. We have purified a 50-kDa form of alboaggregin from the white-lipped tree viper (Trimeresurus albolabris) and two 25-kDa proteins, CHH-A and CHH-B, from the timber rattlesnake (Crotalus horridus horridus) in addition to a previously described 25-kDa alboaggregin and echicetin. Complete or partial amino acid sequencing of CHH-A, CHH-B, and 50-kDa alboaggregin and cross-reactivity of these proteins with an anti-botrocetin antiserum confirmed that they were disulfide-linked heterodimers or higher multimers of the C-type lectin protein family. These proteins, together with 25-kDa alboaggregin and echicetin, specifically bound to GP Ib alpha within the N-terminal peptide domain, His-1-Glu-282, and inhibited vWF binding with comparable IC50 values (approximately 0.2 microgram/mL). However, cross-blocking studies between these structurally related proteins and anti-GP Ib alpha monoclonal antibodies demonstrated that the venom protein binding sites were not congruent. Further, the 50-kDa alboaggregin, but not the other venom proteins, potently induced platelet activation as assessed by dense granule serotonin release or elevation of cytosolic ionized calcium. Treatment of platelets with the 50-kDa alboaggregin was associated with activation of protein kinase C and tyrosine kinase(s), resulting in a platelet protein phosphorylation profile similar to that seen on shear-stress-induced vWF binding to platelets. These results suggest that the 50-kDa alboaggregin induces cytoplasmic signaling coincident with its binding to the GP Ib-IX-V complex and provides a potentially useful probe for studying the mechanism of vWF-dependent platelet activation.

Laboratory diagnosis and molecular epidemiology of an outbreak of hepatitis C virus infection among recipients of human intravenous immunoglobulin in Spain

BACKGROUND

Passive transfer of antibody to hepatitis C virus (HCV) has been thought to occur after infusion of human intravenous immunoglobulin (IVIG), as anti-HCV and/or HCV RNA was commonly found in that product. Recently, however, HCV RNA was detected in the serum of recipients of IVIG. Establishment of a causal relationship between IVIG therapy and HCV infection in recipients was attempted.

STUDY DESIGN AND METHODS

Anti-HCV and HCV RNA sequences were investigated in serum samples from 39 persons who received a human IVIG product in seven different hospitals in Spain. HCV RNA was also investigated in two batches of the IVIG shared by some recipients. All the viral RNA detected were characterized with a line probe assay, restriction fragment length polymorphism analysis of the 5'-noncoding and core regions, and sequencing of the nonstructural 5 region.

RESULTS

On the basis of both clinical and laboratory data, a relationship could be established between the IVIG therapy and the acquisition of the HCV infection by the recipients. Several HCV strains were detected among the recipients, with most of the recipients coming from the same hospital presenting with closely related strains. Moreover, an HCV strain almost identical to the main strain detected among the recipients was found in one batch of the IVIG that probably was shared by most of them. Follow-up studies and evaluation of low-avidity anti-HCV IgG suggested that both acute primary infections and reinfections were produced. In one case, direct evidence of reinfection by a different HCV strain was obtained.

CONCLUSION

The results did not exclude the possibility that a second HCV strain associated with a further, unidentified batch of the IVIG could have contributed to this outbreak.

[Detection of the PML/RAR alpha rearrangement in acute promyelocytic leukemia using a reverse PCR method]

AIMS

This study describes a molecular method of reverse transcription polymerase chain reaction (RT-PCR) to detect the rearrangement PML/RAR alpha in acute promyelocytic leukaemia (APL) in order to assess its specificity and sensibility, and to evaluate its utility in the characterization of APL patients.

PATIENTS AND METHODS

Between January and June of 1995, 64 samples of bone marrow and peripheral blood stem cells (PBSC) cytapheresis were studied. There were 58 APL samples (23 patients: 10 samples obtained with disease activity, 43 samples in complete remission (CR) and 5 PBSC samples) and 6 control samples, of non-APL hematological neoplasms (3 other AML, 1 CML, 1 ALL, and 1 MDS). On the RNA obtained from the isolated mononuclear cells of each sample a conserved region of the PML/RAR alpha fusion gene was amplified by using a RT-PCR with specific primers.

RESULTS

The sensitivity assays were performed by diluting PML/RAR alpha positive RNA samples into RNA of controls. The RT-PCR assay was capable to detect the PML/RAR alpha until an 1/1000 dilution in negative control RNA. Nine out of 58 APL samples failed in the amplification of the control gene, and were considered non-evaluable. None of the 6 control samples showed PML/RAR alpha rearrangement. Nine out of 10 APL samples with disease activity were positive for the presence of PML/RAR alpha (the non-positive sample was a non-evaluable one). Six out of 43 APL samples in CR showed the rearrangement, 3 of them corresponding to 2 patients who posteriory relapsed 12 and 19 months after 1st CR. The other 3 positive samples came from other 3 APL patients (24 months in 3rd CR, 14 months in 1st CR and early CR), who remained in CR at the end of the study. No relapse could be noted in patients with negative PCR samples. PML/RAR alpha was not found in any of the 5 APL PBSC samples studied.

CONCLUSIONS

The RT-PCR method described here seems to be highly specific as it only detects this rearrangement in LPA patients. Furthermore, the presence of PML/RAR alpha in CR patients could be related to relapse. For all these reasons, this molecular method shows great usefulness and can be advocated, not only for assessing diagnosis, but for as monitoring minimal residual disease in the post remission follow up.

Mutant forms of the F protein of human respiratory syncytial (RS) virus induce a cytotoxic T lymphocyte response but not a neutralizing antibody response and only transient resistance to RS virus infection

Vaccinia virus (vv) recombinants expressing either wild-type (VA-F) or mutant forms (VA-FT, VA-FR47, VA-FS1 to VA-FS6) of the fusion (F) protein of respiratory syncytial (RS) virus were examined for their ability to elicit antibody, cytotoxic T lymphocytes (CTL) and protection against RS virus infection in BALB/c mice. Cells infected with the VA-F and VA-FT recombinants expressed the F protein on their surface and mice vaccinated with these recombinants developed RS virus neutralizing antibodies. The VA-FR47 recombinant expressed a mutant form of the F protein (with six amino acid changes from the wild-type) in which both proteolytic processing of the F0 precursor and its transport to the cell surface were inhibited. These mutants induced transient protection against RS virus infection although they did not induce RS virus neutralizing antibodies, or antibodies detectable by ELISA. All the vv recombinants were able to induce an RS virus-specific, MHC class I restricted CTL response. Vaccination of mice with a second set of vv recombinants expressing mutant forms of the F protein showed that the replacement Phe to Ser at amino acid 237 either alone or in combination with others abolished the neutralizing antibody response but did not affect priming of CTLs. These results demonstrate that long-term protection against RS virus infection in mice vaccinated with recombinant vv expressing the F protein is more dependent upon the induction of an antibody rather than a CTL response.

A point mutation in the F1 subunit of human respiratory syncytial virus fusion glycoprotein blocks its cell surface transport at an early stage of the exocytic pathway

Vaccinia virus recombinants expressing either wild-type or mutant forms of human respiratory syncytial (RS) virus (Long strain) fusion (F) glycoprotein were obtained. Proteolytic processing of the precursor, F0, and cell surface transport of the F glycoprotein were unaffected in the recombinants, except in those that contained the replacement Phe --> Ser at position 237 of the F1 subunit. In recombinants containing this mutation, either alone or in combination with others, the traffic of the F molecule was arrested at some intermediate step of its transport to the cell surface and, consequently, the endoproteolytic cleavage of the F0 precursor was inhibited. Immunofluorescence staining of infected cells and endoglycosidase H (Endo-H) sensitivity assays indicated that the arrest occurred before the mid-Golgi compartment. Dimerization and folding of the F protein were also affected by the Phe237 --> Ser substitution. Other amino acid replacements at positions 236 or 237 of the F1 subunit had various effects upon F0 maturation. These results are discussed in terms of the maturation requirements for the RS virus F molecule.

Specific oncological contribution of cathepsin D and pS2 in human breast cancer: their relationship with TNM status, estradiol receptors, epidermal growth factor receptor and neu amplification

The present study attempts to clarify the specific contribution of cathepsin D (CD) and pS2 to the progression of breast cancer (BC) by examining the relationship between these two factors and TNM status, tumour grade, estradiol receptors (ER) and the prognosis factors epidermal growth factor receptor (EGFR) and neu amplification in a group of 270 BC patients. CD and pS2 were determined by an immunoradiometric procedure in tumour cytosols obtained for ER. Neu amplifications were evaluated by dot-blot, in tumour DNA. EGFR was determined in membrane tumour preparations obtained from ER cytosols by a two-point radiometric saturation assay. CD is basically related to bad prognosis factors and has a direct correlation with tumour size (P = 0.025) and EGFR content (P = 0.007) and is associated with the presence of metastases (P = 0.000). pS2 is mostly related to good prognosis factors and showed an inverse correlation with the Scarff-Bloom Index (P = 0.011) and a direct correlation with ER content (P = 0.014). Finally, pS2 and CD also showed a strong mutual association (P = 0.009) and the fact that both correlated with ER content confirms in tumours the experimental finding that they are estrogen-induced proteins.

Biosynthetic defect in platelet glycoprotein IX mutants associated with Bernard-Soulier syndrome

To evaluate the biosynthetic basis for decreased glycoprotein (GP) Ib-IX expression resulting from GP IX mutations described in three siblings with Bernard-Soulier syndrome, we introduced each mutation into the cDNA for GP IX by site-directed mutagenesis (GP IX Asp21 --> Gly and GP IX Asn45 --> Ser) and examined the associations of the mutants with the two other subunits of the GP Ib-IX complex in transfected cells. Unlike wild-type GP IX, neither of the mutants was able to increase GP Ib expression on the cell surface, either when transfected into Chinese hamster ovary (CHO) alpha beta cells or when cotransfected with GP Ib alpha and GP Ib beta into wild-type CHO cells. We also evaluated whether cotransfecting wild-type or mutant GP IX with GP Ib beta would result in the appearance of GP IX on the surface of the transfected cells; the wild-type protein was detected on the surface of the cells, whereas neither mutant reached the cell surface in appreciable quantities. Immunofluorescence microscopy of permeabilized cells revealed that the failure to express mutant GP IX on the cell surface did not result from failure to synthesize the polypeptide. Both mutants were detected in intracellular compartments, albeit at lower levels than the wild-type polypeptide (the fluorescence of cells expressing the GP IX Asp21 --> Gly was consistently the lowest). Direct evidence that the mutants associate poorly with Gp Ib beta was obtained of 35S-labeled cells transiently expressing GP Ib beta and wild-type or mutant GP IX. The amount of GP IX coprecipitated with GP Ib beta was greatly diminished in cells expressing either mutant. These findings suggest an important role for the conserved leucine-rich motif of GP IX in the association of this polypeptide with GP Ib beta and provide further evidence for the importance of GP IX in the stability of the GP-Ib-IX complex.

[Epidemic outbreak of hepatitis B from the tattoo in gypsy families]

BACKGROUND

To document an outbreak of Hepatitis B in a gypsy community in the Upper Aragón region, as well as the control measures adopted.

METHODS

Documented study of Hepatitis B cases and families, including an epidemiological survey and the determining of hepatitis B viral indicators (MVHB) using immunoenzymatic methods.

RESULTS

84.8% participation (39/45). During the months of February and March 1988, 5 cases of Hepatitis B were detected in a gypsy community in the Upper Aragon region (12.8% attack rate, 5/39), with an average age of 13.0 + 7.3, (4 women and one man). Four of the cases detected had previously undergone tatooing. The fifth case was due to direct transmission from mother to a recently born child. The MVHB study of families showed a further two cases. MVHB rate being 17.9% (7/39). Vaccinations were given to all persons susceptible to the disease.

CONCLUSIONS

It is suggested that tatooing could be a significant factor to be considered in relation to the transmission of Hepatitis B in gypsy communities. Due to the high rate of incidence of the disease in this ethnic group, general vaccination is prescribed.

Detection of antibody to hepatitis C virus E2 recombinant antigen among samples indeterminate for anti-HCV after wide serological testing and correlation with viremia. The Spanish Study Group for Blood Donors at Risk of Transmission of HCV

The detection of antibody to the second envelope protein (E2) of the hepatitis C virus (HCV) has been hampered by the lack of suitable antigens. A previously described E2 recombinant antigen (CHO-E2) expressed as a non-fused, highly glycosylated protein in mammalian cells was used to detect specific antibody (anti-E2) in samples from blood donors and viraemic patients showing positive or indeterminate results for anti-HCV after a wide serological study. Anti-E2 was detected in 50-75% of the donors positive for anti-HCV, 80% of viraemic immunocompetent patients with anti-NS3 alone and 28% of non-viraemic donors with anticore alone. In donors with anti-NS3 (15 samples) or anti-NS4 (51 samples) alone, anti-E2 was found occasionally (3 cases). Moreover, two anti-E2-positive samples from viraemic patients were misidentified by some commercial assays for screening anti-HCV. These results suggest that testing for anti-E2 may be useful for improving the performance of the current assays for anti-HCV screening and confirmation.

Aggregation of mammalian cells expressing the platelet glycoprotein (GP) Ib-IX complex and the requirement for tyrosine sulfation of GP Ib alpha

The glycoprotein (GP) Ib-IX complex mediates platelet aggregation in response to high shear forces by binding von Willebrand factor (vWF) in the plasma. We investigated the possibility that the complex could mediate a similar phenomenon if expressed in nonhematopoietic cells. When agitated on a tabletop shaker, CHO and L cells expressing the full complex formed large aggregates in the presence of vWF and the modulator ristocetin. When the rate of agitation was increased, aggregation occurred without added ristocetin and appeared to require only the application of a physical force. The aggregation was homophilic and temperature-dependent and required a functional ligand-binding subunit of the GP Ib-IX complex, GP Ib alpha. Posttranslational tyrosine sulfation of GP Ib alpha was required for aggregate formation and stability. Thus, aggregation of cells expressing the GP Ib-IX complex is a unique example of a ligand-receptor interaction induced by mechanical forces and demonstrates an important biological role for sulfation of tyrosine residues.

Expression of platelet glycoprotein (GP) V in heterologous cells and evidence for its association with GP Ib alpha in forming a GP Ib-IX-V complex on the cell surface

The glycoprotein (GP) Ib-IX-V complex comprises four polypeptides: the subunits of the GP Ib-IX complex (GP Ib alpha, GP Ib beta, GP IX) and GP V. To determine the requirements for cell-surface expression of GPV, we transiently expressed the recombinant polypeptide in wild-type Chinese hamster ovary (CHO) cells by cotransfection with plasmids for the subunits of the GP Ib-IX complex and in CHO cells that stably express different combinations of the GP Ib-IX complex subunits. Glycoprotein V expressed alone was detectable on the cell surface, and the level was not augmented by cotransfection with any one of the subunits of the GP Ib-IX complex. However, when GP V was expressed in cells that stably express combinations of GP Ib-IX complex subunits, its expression on the cell surface was greater in all the cell lines that contained GP Ib alpha than in wild-type CHO cells. That GP V associates with GP Ib alpha was also suggested by confocal microscopy studies: GP V colocalized with GP Ib alpha in CHO alpha beta IX (cells that express GP Ib alpha, GP Ib beta, and GP IX), CHO alpha beta, and CHO alpha IX cells, but did not colocalize with GP Ib beta in CHO beta IX cells. Similarly, immunoprecipitation of GP V from cells expressing GP Ib alpha led to coprecipitation of the latter polypeptide; neither GP Ib beta nor GP IX coprecipitated with GP V from CHO beta IX cells. Taken together, these data indicate that GP V associates with the GP Ib-IX complex through a direct interaction with GP Ib alpha and establish the topology of the GP Ib-IX-V subunits on the cell surface.

Bowel inflammation in anterior uveitis and spondyloarthropathy

OBJECTIVE

To assess the possible involvement of the bowel in the spectrum of anterior uveitis (AU).

METHODS

Ileocolonoscopy and histology studies were performed on 27 patients with AU.

RESULTS

Patients with AU had a higher incidence of chronic intestinal inflammation (CII) than controls. CII was present in AU regardless of HLA-B27 status, sacroiliitis or NSAID intake, and was more prevalent in uveitis with high recurrence.

CONCLUSION

Bowl inflammation ia a component of the spectrum of AU. This finding supports a HIL-B27 independent common pathogenic link between AU and spondyloarthropathy.