Oligoclonal CD4+ CD57+ T-cell expansions contribute to the imbalanced T-cell receptor repertoire of rheumatoid arthritis patients

A peculiar feature of rheumatoid arthritis patients is that they carry clonally expanded CD4+ and CD8+ cells in the peripheral blood. While the distortion of the repertoire of CD8+ cells has been ascribed to the increase of CD8+ CD57+ large granular lymphocytes, often detected in these patients, the mechanism responsible for the clonal expansion of CD4+ cells remains unexplained. Here, we report that CD4+ CD57+ cells, that in healthy individuals represent a small subset of peripheral CD4+ lymphocytes, are significantly expanded in the peripheral blood of a considerable percentage of rheumatoid arthritis patients. Furthermore, the expansion of these lymphocytes appears to correlate with the presence of rheumatoid factor. The molecular analysis of the T-cell receptor variable beta segments expressed by the CD4+ CD57+ cells enriched in rheumatoid arthritis patients showed that they use restricted repertoires, that partially overlap with those of their CD4- CD57+ counterpart. The structural feature of the receptor ligand expressed by these cells revealed that their expansion is most likely mediated by strong antigenic pressures. However, since we also found that CD4+ CD57+ and CD4- CD57+ cells can share the same clonal specificity, it is likely that their selection is not mediated by conventional major histocompatibility complex restricted mechanisms. Thus, while our data demonstrate that CD4+ CD57+ cells play an important role in establishing the imbalance of the CD4+ cell repertoire observed in rheumatoid arthritis patients, they also suggest that these cells have common features with mouse CD4+ CD8- NK1.1+/T cells.     

IL-2 and IL-7 differentially induce CD4-CD8- alpha beta TCR+NK1.1+ large granular lymphocytes and IL-4-producing cells from CD4-CD8- alpha beta TCR+NK1.1- cells: implications for the regulation of Th1- and Th2-type responses

Effector functions of CD4-CD8- double negative (DN) alpha beta TCR+ cells were examined. Among mouse DN alpha beta TCR+ thymocytes, NK1.1+ cells expressing a canonical V alpha 14/J alpha 281 TCR but not NK1.1- cells produce IL-4 upon TCR cross-linking and IFN-gamma upon cross-linking of NK1.1 as well as TCR. Production of IL-4 but not IFN-gamma from DN alpha beta TCR+NK1.1+ cells was markedly suppressed by IL-2. Whereas V alpha 14/J alpha 281 TCR+ cells express NK1.1+, these cells are not the precursor of DN alpha beta TCR+NK1.1+CD16+B220+ large granular lymphocytes (LGL). IL-2 induces rapid proliferation and generation of NK1.1+ LGL from DN alpha beta TCR+NK1.1- but not from DN alpha beta TCR+NK1.1+ cells. LGL cells exhibit NK activity and produce IFN-gamma but not IL-4 upon cross-linking of surface TCR or NK1.1 molecules. In contrast to IL-2, IL-7 does not induce LGL cells or NK activity from DN alpha beta TCR+NK1.1- cells but induces the ability to produce high levels of IL-4 upon TCR cross-linking. Our results show that DN alpha beta TCR+ T cells have several distinct subpopulations, and that IL-2 and IL-7 differentially regulate the functions of DN alpha beta TCR+ T cells by inducing different types of effector cells.     

Adoptively transferred CD4+ lymphocytes from CD8 -/- mice are sufficient to mediate the rejection of MHC class II or class I disparate skin grafts

Recent studies revealed that CD4+ cells initiate allograft rejection through direct recognition of allogeneic MHC class II Ags and indirect recognition of MHC peptides processed by self APCs. Both pathways were shown to help CD8+ cells that eventually lysed allogeneic MHC class I-presenting targets. There was little evidence, however, that CD4+ cells are sufficient for graft rejection. We studied skin graft rejection by CD8-deficient (CD8 -/-) mice. We showed that BALB/cJ(H-2d) CD8 -/- mice could reject allogeneic skin from C57BL/6J(H-2b) mice deficient in MHC class I or in MHC class II Ags. To understand the role of CD4+ cells in this process, we isolated them from CD8 -/- mice and transferred them to BALB/cJ nude mice that had been grafted with allogeneic skin (H-2b) from animals deficient in MHC class I or MHC class II. Nude mice injected with CD4+ cells rejected MHC class II and, albeit more slowly, MHC class I disparate skins. We showed in vitro evidence that CD4+ cells were not cytotoxic toward MHC class I or MHC class II disparate targets and that they recognized MHC class I allogeneic targets through indirect recognition. CD4+ cells produced Th1 cytokines, but not IL-4, following stimulation with allogeneic cells. Furthermore, intragraft TNF-alpha was elevated in skin grafted onto nude mice reconstituted with CD4+ cells compared with nonreconstituted mice. This suggests that MHC class II- or MHC class I-guided CD4+ cells alone are sufficient to induce rejection by the generation of cytokine-induced lesions.     

Active immunity against the CD4 receptor by using an antibody antigenized with residues 41-55 of the first extracellular domain

Using the process of "antibody antigenization," we engineered two antibody molecules carrying in the third complementarity-determining region of the heavy chain variable domain a 7-mer or a 15-mer peptide epitope of the first extracellular domain (D1) of human CD4 receptor--namely, Ser-Phe-Leu-Thr-Lys-Gly-Pro-Ser (SFLTKGPS; positions 42 through 49) and Gly-Ser-Phe-Leu-Thr-Lys-Gly-Pro-Ser-Lys-Leu-Asn-Asp-Arg-Ala (GSFLTKGPSKLNDRA; positions 41 through 55). These amino acid sequences are contained in the consensus binding site for the human immunodeficiency virus (HIV) on CD4 receptor. Both antigenized antibodies (AgAbs) bound recombinant gp120 and were recognized by a prototype monoclonal antibody to CD4 whose binding site is within amino acid residues 41-55. AgAbs were then used as immunogens in rabbits and mice to elicit a humoral response against CD4. Only the AgAb carrying the sequence 41GSFLTKGPSKLN-DRA55 induced a response against CD4. The induced antibodies showed specificity for the amino acid sequence of CD4 engineered in the AgAb molecule, were able to inhibit the formation of syncytia between human CD4+ T cells MOLT-3 and 8E5 (T cells that are constitutively infected with HIV), and stained human CD4+ CEM T cells. Four murine monoclonal antibodies were used to analyze the relationship between syncytia inhibition and CD4 binding at the single antibody level, and indicated that recognition of native CD4 is not an absolute requirement for inhibition of syncytia. This study demonstrates that antigenized antibodies can be used as immunogens to elicit site-specific and biologically active immunity to CD4. The importance of this approach as a general way to induce anti-receptor immunity and as a possible new measure to immunointervention in HIV infection is discussed.     

The cell-mediated response to schistosomal antigens at the clonal level. III. Identification of soluble egg antigens recognized by cloned specific granulomagenic murine CD4+ Th1-type lymphocytes

Granulomatous inflammation in schistosomiasis is a consequence of T cell-mediated hypersensitivity to parasite egg Ag. In the present study we used three consecutive independent chromatographic procedures to fractionate and identify the soluble egg Ag recognized by schistosome-specific, cloned, murine, CD4+ Th1-type lymphocytes, which had been shown previously to be capable of mediating granuloma formation in vivo when adoptively transferred to normal syngeneic hosts challenged with an i.v. injection of eggs. The stimulatory activity resided in two acidic egg molecules, with apparent molecular masses of 64 to 68 kDa and 38 to 42 kDa, each of which ran as a single band on SDS-PAGE after purification. Fast performance liquid chromatography and SDS-PAGE performed under reducing conditions suggested that the two molecules are related and that the 38- to 42-kDa molecule is a subunit of the 64- to 68-kDa molecule. Polyclonal lymphoid cells from schistosome-infected mice were similarly stimulated by the purified 64- to 68-kDa and 38- to 42-kDa molecules, implying that these are sensitizing Ag in the natural disease.