Identification of an important thyrotrophin binding site on the human thyrotrophin receptor using monoclonal antibodies.

A thyrotrophin (TSH) binding site has been identified on the extracellular domain of the human thyrotrophin receptor (hTSHR) using monoclonal antibodies that recognise the native hTSHR. These antibodies were produced by immunising BALB/c mice with denatured recombinant material, selected by their reaction with recombinant hTSHR expressed on heterologous cell lines using flow cytofluorimetric analysis, and characterised by immunoblotting and immunoprecipitation. The epitopes the monoclonal antibodies recognise were determined using multiple overlapping synthetic peptides. All of the antibodies reacted with epitopes within the region 335-390; these epitopes must be accessible on the external surface of the native hTSHR. None of the antibodies stimulated cAMP production of recombinant hTSHR cell lines. The epitopes of two antibodies (residues 337-342 and 355-358) are in the small peptide thought to be removed by proteolytic processing of hTSHR. A further five different antibodies (determined from their variable region sequences) all reacted with residues 381-384 emphasising the immunogenicity of this region. The functional importance of residues 381-384 as a TSH binding site was shown by the fact that some of these monoclonal antibodies caused inhibition of radiolabelled TSH binding of 80-90% at 1 microg/ml and greater than 50% inhibition at 0.1 microg/ml (0.65 nM--i.e. comparable in effectiveness with TSH itself). Residues 381-384 may form part of the target regions recognised by inhibitory autoantibodies found in Graves' disease.

Proliferative T cell responses to the human papillomavirus type 16 E7 protein in women with cervical dysplasia and cervical carcinoma and in healthy individuals.

The levels of proliferative T cell responses to peptides representing the human papillomavirus type 16 (HPV-16) E7 protein have been measured using short-term T cell lines derived from peripheral blood of healthy women and those with cervical dysplasias and carcinoma of the cervix. In healthy individuals 47 percent (7/15) responded predominantly to the N- and C-terminal regions of the protein and 6/7 responders were to a single peptide between amino acids 80-94. In comparison 29 percent (9/31) of women with cervical dysplasia responded to HPV-16 E7, with a significantly reduced response to both the N- and C-terminal regions (P = 0.03 and 0.038, respectively). A higher proportion of responders was found in patients with high grade lesions (56 percent, 5/9) versus those with atypical or low grade histology (20 percent, 4/20) and the response to a single peptide between amino acids 75-94 was also increased in this patient group (P = 0.044). This may be a reflection of higher levels of current or previous exposure to HPV-16 in patients with high grade lesions. Correlation of T cell responses with HPV DNA type (detected by PCR of cervical biopsy tissue) showed that 3/9 (33 percent) HPV-16 DNA-positive individuals responded. This suggests that E7 may not be the dominant target of the immune response or that the response to E7 is down-regulated in these patients. In addition 4/18 (22 percent) HPV-16 DNA-negative individuals responded, suggesting that their T cells may have been primed by previous exposure to HPV-16 or that a cross-reactive response was detected. Proliferative T cell responses to both HPV-16 E7 and L1 were reduced in women with cervical carcinoma in comparison to those with cervical dysplasia and healthy controls. The observed down-regulation of responses to HPV-16 E7 in women with cervical dysplasia and cervical carcinoma may reflect an altered functional balance between subsets of T helper cells in HPV-16 infections.

Proliferative T cell responses to human papillomavirus type 16 L1 peptides in patients with cervical dysplasia.

Human papillomavirus type 16 (HPV-16) can cause genital warts, cervical dysplasias and carcinoma of the cervix. Cell-mediated immunity is thought to be important in protection against the virus and in its elimination, but little is known about the mechanisms involved. In a cross-sectional study we have demonstrated proliferative T cell responses to peptides representing the HPV-16 L1 capsid protein (aa 199-409) in the peripheral blood of 63% of patients (n = 41) with histological evidence of cervical dysplasia and in 45% of healthy age-matched controls (n = 11). This was achieved by generating short-term T cell lines (STLs) from each individual in vitro against a beta-galactosidase-HPV- 16 L1 (aa 199-409) fusion protein for 2 weeks, and then identifying the HPV epitopes they recognized with overlapping synthetic peptides (15-mers) spanning this region in 3 day specificity assays. Histological grading and HPV typing by PCR were performed on patients' cervical biopsies taken at the same clinical visit as the peripheral blood samples. An immunogenic region was identified between aa 311-345 in 73% of patients (18% in controls) who responded to HPV-16 L1 (aa 199-409). The number of responders to this region was significantly higher in patients with HPV-16-positive biopsies when compared to those with HPV-16-negative biopsies (P = 0.006), as was the number of responders to individual peptides 311-325 (NLASSNYFPTPSGSM; p = 0.04) and 321-335 (PSGSMVTSDAQIFNK; P = 0.004) representing this region. The mean level of response to each individual peptide was also higher in the patient group than the controls (P < 0.05). The most significant finding was that all patients with evidence of a current HPV-16 infection responded to one or more L1 peptides (P = 0.0004) and 92% had high grade cervical intraepithelial neoplasia (CIN III). We also found that the CIN III group was more likely to respond to any L1 peptide than either the atypical group (P = 0.04) or the controls (P = 0.05). Data from four individuals showed that the majority of peptide-specific STLs were CD4+ but some CD8+ STLs were also detected.

Monoclonal antibodies that recognize the native human thyrotropin receptor.

Monoclonal antibodies have been produced that recognize the native human thyrotropin receptor by using a sensitive screening protocol based on flow cytofluorimetry combined with recombinant eukaryotic cells expressing high levels of the full-length functional receptor. The more standard screening method of ELISA preferentially selected antibodies that only reacted with the denatured receptor. Mice were immunized with recombinant receptor produced in either eukaryotic or prokaryotic systems; after screening and cloning, three stable hybridoma lines were established. An IgM antibody (7B5) produced in response to the eukaryotic material recognized only the native receptor (by flow cytofluorimetry) and did not react with denatured material on ELISA or immunoblotting, suggesting that its epitope is conformational. In contrast, two IgG1 antibodies (2C11 and 3B12) produced in response to the prokaryotic material recognized both native and denatured receptor (by flow cytofluorimetry, immunoprecipitation and immunoblotting). The use of different recombinant constructs in the immunoblotting procedure allowed the epitopes for both the IgG1 antibodies to be assigned to the region 125-369. None of the antibodies stimulated production of cAMP by recombinant cells expressing the full-length functional receptor, but one of the IgG1 antibodies (2C11) did inhibit binding of radiolabelled thyrotropin to these same cells. These antibodies, and others that can now be produced with this screening protocol, will help define the relationship between structure and function of this important receptor.

Preliminary characterisation of antigens recognised by monoclonal antibodies raised to Porphyromonas gingivalis and by sera from patients with periodontitis.

A panel of 15 monoclonal antibodies (MAbs) was raised to Porphyromonas gingivalis and used to characterise the antigens which they recognise by ELISA, immunofluorescence (IF), Western blotting and patient serum inhibition studies. All the MAbs were specific for P. gingivalis and did not recognise 24 other species. Eight MAbs gave bright ring-like staining patterns against the majority of serotypes of P. gingivalis tested by IF. The antibodies could be grouped into 5 different antigen recognition profiles on Western blotting, and ELISA indicated that 8 of them bound to a capsular extract. Five antibodies bound to antigenic determinants recognised by sera from patients with periodonitis and 4 of these (1A1, 2B/H9, 3B1, 7D5) bound to a P. gingivalis 47kDa protease preparation on Western blotting. These antibodies are potentially useful for the purification and characterisation of biologically active components of P. gingivalis that are recognised by sera from patients with periodontitis.

T cell responses to the human papillomavirus type 16 E7 protein in mice of different haplotypes.

The response of murine T cells to the E7 molecule of human papillomavirus type 16 (HPV-16) was studied using eight different mouse strains of six distinct H-2 haplotypes. HPV-16 E7 protein was prepared as a fusion protein with glutathione-S-transferase, purified by affinity chromatography and used for immunization. Cells from the lymph nodes were cultured with whole fusion protein, glutathione-S-transferase or HPV-16 E7 protein synthetic peptides. All the mouse strains tested, with the exception of BALB/c, recognized the E7 molecule, as evidenced by a proliferative response to at least two of the peptides. The profile of responses to peptides varied between and within a strain, but five distinct immunodominant regions could be identified. These regions were defined on the basis of a reaction to one or more peptides in a given part of the E7 molecule by at least four strains. The five regions were encompassed by amino acid residues 1 to 9, 17 to 32, 42 to 59, 62 to 77 and 87 to 98. The findings suggest that in an outbred population, such as man, the E7 molecule of HPV-16 would be recognized by a large proportion of the population. However, the poor response of two mouse strains [B10.RIII (71NS) and BALB/c] could also have a corollary in man.