Arthur W. Boylston

Intra-articular primatised anti-CD4: efficacy in resistant rheumatoid knees. A study of combined arthroscopy, magnetic resonance imaging, and histology

OBJECTIVES CD4+ T cells sustain the chronic synovial inflammatory response in rheumatoid arthritis (RA). SB-210396/CE 9.1 is an anti-CD4 monoclonal antibody that has documented efficacy in RA when given intravenously. This study aimed to establish the safety and efficacy of the intra-articular administration of SB-210396/CE 9.1 compared with placebo, examining its mode of action using a combined imaging approach of arthroscopy, magnetic resonance imaging (MRI), and histology. METHODS Thirteen RA patients with active, resistant knee synovitis, were randomised to intra-articular injection of placebo (n=3), 0.4 mg (n=3) or 40 mg (n=7) of anti-CD4 after sequential dynamic gadolinium enhanced MRI, followed by same day arthroscopy and synovial membrane biopsy. Imaging and arthroscopic synovial membrane sampling were repeated at six weeks. This study used a unique region of interest (ROI) analysis mapping the MRI area analysed to the specific biopsy site identified arthroscopically, thus providing data for all three modalities at the same synovial membrane site. RESULTS 12 patients completed the study (one placebo treated patient refused further MRI). Arthroscopic improvement was observed in 0 of 2 placebo patients but in 10 of 10 patients receiving active drug (>20% in 6 of 10). Improvement in MRI was consistently observed in all patients of the 40 mg group but not in the other two groups. A reduction in SM CD4+ score was noted in the 40 mg group and in the 0.4 mg group. Strong correlations both before and after treatment, were identified between the three imaging modalities. Intra-articular delivery of SB-210396/CE 9.1 was well tolerated. CONCLUSIONS SB-210396/CE 9.1 is safe when administered by intra-articular injection. A trend toward efficacy was found by coordinated MRI, arthroscopic, and histological imaging, not seen in the placebo group. The value of ROI analysis was demonstrated.

Rheumatoid arthritis synovial T cells regulate transcription of several genes associated with antigen-induced anergy

Rheumatoid arthritis (RA) is a chronic, inflammatory synovitis whose pathogenesis may involve autoimmune mechanisms. Anergy is a state of T-cell nonresponsiveness characterized by downregulated IL-2 production. Paradoxically, RA T cells are hyporesponsive and proliferate poorly to antigens and mitogens, thus sharing some characteristics with anergic T cells. We analyzed the molecular basis of anergy in cloned human CD4+ T cells using differential display RT-PCR and subsequently examined the levels of differentially expressed transcripts in RA and, as control, reactive arthritis (ReA) synovium. Several transcriptional events were common to anergic T cells and RA synovium. These included downregulation of CALMODULIN:, which is critical to T-cell activation, and of cellular apoptosis susceptibility protein, which may mediate resistance to apoptosis in RA. Transcription of CALMODULIN: in RA synovium was less than 1% of that in ReA and was lower in RA synovial fluid mononuclear cells than in paired PBMCs. Following anti-TNF-alpha therapy in vivo, RA PBMC CALMODULIN: transcripts increased five- to tenfold. Pharmacological calmodulin blockade in vitro impaired antigen-specific proliferation. These data provide a link between reduced CALMODULIN: transcription and impaired T-cell responsiveness in RA. The identification of transcriptional changes common to anergic and RA synovial T cells should help interpret some of the characteristic RA cellular defects.

Analysis of Fcγ receptor haplotypes in rheumatoid arthritis: FCGR3A remains a major susceptibility gene at this locus, with an additional contribution from FCGR3B

The Fcγ receptors play important roles in the initiation and regulation of many immunological and inflammatory processes, and genetic variants (FCGR) have been associated with numerous autoimmune and infectious diseases. The data in rheumatoid arthritis (RA) are conflicting and we previously demonstrated an association between FCGR3A and RA. In view of the close molecular proximity with FCGR2A, FCGR2B and FCGR3B, additional polymorphisms within these genes and FCGR haplotypes were examined to refine the extent of association with RA. Biallelic polymorphisms in FCGR2A, FCGR2B and FCGR3B were examined for association with RA in two well characterized UK Caucasian and North Indian/Pakistani cohorts, in which FCGR3A genotyping had previously been undertaken. Haplotype frequencies and linkage disequilibrium were estimated across the FCGR locus and a model-free analysis was performed to determine association with RA. This was followed by regression analysis, allowing for phase uncertainty, to identify the particular haplotype(s) that influences disease risk. Our results reveal that FCGR2A, FCGR2B and FCGR3B were not associated with RA. The haplotype with the strongest association with RA susceptibility was the FCGR3A–FCGR3B 158V-NA2 haplotype (odds ratio 3.18, 95% confidence interval 1.13–8.92 [P = 0.03] for homozygotes compared with all genotypes). The association was stronger in the presence of nodules (odds ratio 5.03, 95% confidence interval 1.44–17.56; P = 0.01). This haplotype was also more common in North Indian/Pakistani RA patients than in control individuals, but not significantly so. Logistic regression analyses suggested that FCGR3A remained the most significant gene at this locus. The increased association with an FCGR3A–FCGR3B haplotype suggests that other polymorphic variants within FCGR3A or FCGR3B, or in linkage disequilibrium with this haplotype, may additionally contribute to disease pathogenesis.

Large granular lymphocyte expansions in patients with Felty's syndrome: analysis using anti‐T cell receptor Vβ‐specific monoclonal antibodies

Feltys syndrome (FS), the association of rheumatoid arthritis (RA) and idiopathic neutropenia, remains an unexplained phenomenon. HLA‐DR4 is found in over 90% of cases. Patients with FS may have a T cell lymphocytosis of CD3+CD8+CD57+ large granular lymphocytes (LGL syndrome). In this study of 47 patients with FS, 19% had clear evidence for LGL expansions, while in total 42% had variable evidence for the LGL syndrome using currently available techniques. Of these T cell expansions, 76% were clonal, as demonstrated by Southern blotting and analysis with T cell receptor (TCR) β chain constant region probes. This technique may fail to detect clonal populations in some patients. Cytofluorographic analysis using antibodies specific for TCR β chains identified patients with clonal LGL expansions with results comparable to those obtained with Southern blotting. No evidence for shared Vβ usage among expansions from different patients was seen. The role of LGL in RA and FS is currently unclear, but this technique offers a practical and accessible means of identifying patients with LGL expansions, as a starting point for further investigation.

The human T cell antigen receptor repertoire: skewed use of Vβ gene families by CD8+ cells

The TCR repertoire of human CD8+ peripheral blood lymphocytes has been determined using MoAbs to the Vβ2, 3,5.1,5.2/5.3,6.7,8,12 and 19(17) Vβ gene families. The CD8 T cell repertoire for Vβ2 and Vβ3 is shown to be skewed, with an excess of individuals having higher values than are consistent with a normal distribution. A significant majority of these individuals are over the age of 40. High values of Vβ CD8+ cells were found for each Vβ family studied except for 6.7a. Individual high values are stable for at least 12 months. In addition, the total percentage of CD4 and CD8 cells reacting with this panel of reagents was determined. There is a significant excess of Vβ+ CD4+ cells (33%) over CD8+Vβ+ cells (21·9%). Thus the human CD8 Vβ repertoire differs from the human CD4 repertoire in a number of important ways.

Persistence of clonal T‐cell expansions following high‐dose chemotherapy and autologous peripheral blood progenitor cell rescue

Analysing the regeneration of T lymphocytes after high‐dose chemotherapy with autologous peripheral blood progenitor cell rescue (PBPCR) may help elucidate the mechanisms of immune recovery. The T‐cell receptor variable beta chain (TCRBV) repertoire of adult patients undergoing high‐dose chemotherapy was analysed by flow cytometry, before and after treatment. Four patients were found to have a stable expansion present (TCRBV3, 17, 21 and 22) ranging from 8% to 42% of the CD4+ or CD8+ repertoire. We demonstrated that, in these patients, following high‐dose chemotherapy and autologous stem cell transplantation, the clonal expansions reappeared in peripheral blood and returned to pretransplant levels. Three expansions (CD3+CD8+TCRBV3+, CD3+CD4+TCRBV21+ and CD3+CD8+TCRBV22+) were further defined by sequence analysis of the complementarity‐determining region (CDR)3 portion within the TCR rearrangements. These were shown to be predominantly clonal, with the same sequences being identified in peripheral blood before and after PBPCR, providing evidence that the overwhelming majority of T cells in these expansions arise from mature lymphocytes. This study demonstrated that patients undergoing autologous PBPCR for high‐dose chemotherapy regenerate clonal expansions, consistent with pretreatment levels. They also regenerate T‐cell repertoires with each TCRBV family represented to a similar level as that prior to high‐dose chemotherapy.

Malaria is not responsible for the selection of TCR β-subunit variable gene haplotypes in The Gambia

Abstract. Previous work has shown that a single haplotype of the T-cell antigen receptor β-subunit (TCRB) locus is predominant in African populations. This is likely to be due to selection pressure for gene(s) that protect children against disease. This study has tested the hypothesis that malaria is the responsible selection pressure, due to its impact on child mortality. The haplotypes of BV8S3, BV2S1, BV15S1, and BV3S1 were determined in children suffering from severe malaria and unaffected adult controls. No significant difference between cases and controls was shown for any of the haplotypes studied. In addition, an insertion/deletion (INDEL) haplotype in the 5′ region of the TCRB locus was investigated. Again no differences between the two groups were detected. Therefore, the evidence suggests that malaria is not responsible for haplotype selection in The Gambia.

Predominance of one T-cell antigen receptor BV haplotype in African populations.

Abstractu2002The human T-cell antigen receptor (TCR) is the counter-receptor for the HLA/peptide complex displayed on the surface of antigen-presenting cells. It confers antigen specificity on T lymphocytes and therefore plays a central role in pathogen recognition and host response. The most frequently used form of the TCR is a heterodimer composed of variable α and β chains. We investigated allele frequencies for four variable-region gene segments of the β chain (2S1, 3S1, 8S3, and 15S1) in 146 Caucasians and 165 Africans. The results reveal significant unexpected differences between the two populations for allele frequencies, phenotypes, genotypes, and haplotypes. Among Caucasians, there are 43 phenotypes, whereas there are 31 among the Africans studied. There are 17 haplotypes in the Caucasian sample but only 10 in Africans. This loss of diversity is largely due to the high frequency of one haplotype in the African sample which represents 65% of the informative chromosomes. At least one copy of this haplotype is present in 90% of informative individuals. As a result, 29% of Africans are homozygous for the common haplotype. Less genetic diversity at TCRBV is unexpected, since Africans usually show greater genetic diversity than other ethnic groups. For example, there are approximately twice as many HLA haplotypes in Africans compared to Caucasians. Homozygosity is also unexpected because it reduces the number of TCR variants available to recognize HLA pathogen-derived peptide complexes.

Regulation of Activation and Proliferation in T Cells

The emphasis in studies of lymphocyte function has shifted in recent years from the definition of functionally distinct subsets, using phenotypic markers for cell separation, to studies of the function of cell surface molecules. This change has been brought about by the development of monoclonal antibodies (mAbs) and monoclonal cell sources. The former have provided reagents for identifying and characterizing molecules and the latter, cell populations which can be manipulated in vitro under relatively defined conditions. Nevertheless, since it is a feature of the immune system that no cell type functions in isolation, results obtained with interleukin-2 (IL-2)-dependent clones or tumors need to be confirmed with polyclonal populations. Further, the requirements for activation of resting cells may not be identical to those for restimulation of in vitro grown and already activated cells.

Unique TCR β-subunit variable gene haplotypes in Africans

Abstract. This study investigated polymorphisms of genes in two regions of the T-cell antigen receptor β-subunit (TCRB) locus, including BV9S2P, and BV6S7 in a 5′ linkage group, and BV8S3, BV24S1, BV25S1, BV18S1, BV2S1, BV15S1 and BV3S1 in a 3′ linkage group. These loci have been genotyped in individuals from five regions in Africa, including The Gambia, Nigeria, Cameroon, Tanzania, and Zambia, and in individuals from northern Britain, northern India, and Papua New Guinea (PNG). In the 3′ linkage group, 11 unique haplotypes were identified in the combined African populations; two equally frequent haplotypes represent the majority of African chromosomes. One haplotype was found in all four regions studied. This is the most frequent haplotype in the northern British, northern Indian and PNG populations. Although present, it is infrequent in the African populations. A North-South gradient in the frequency of a common African haplotype was observed. The distribution did not represent that of a known disease. Evidence suggests that malaria is not responsible for selection of these haplotypes. Overall, this study highlights large differences in the genetic constitution of the TCRB locus between Africans and other populations.