Local Clonal Expansion Research Articles

Distinct T-cell clonal expansion in the vicinity of tumor cells in plasmacytoma

Although various clinical observations suggested that myeloma cell growth might be modulated by the immune system, evidence supporting the in situ immunogenicity of myeloma cells remains scarce. The authors reasoned that if there is any specific T-cell/tumor cell interaction in myeloma, it is most likely reflected in the T-cell population in the vicinity of the tumor cells. The authors used a molecular method to compare the T-cell populations in the vicinity of tumor cells with those in the peripheral blood in patients with plasmacytomas and multiple myeloma. Six patients were studied. When compared with the peripheral blood from the corresponding patients, T cells in the vicinity of tumor cells in five of the six patients showed significant contraction of the T-cell receptor (TCR) Vbeta repertoire. In addition to this, the T cells isolated from the sites of the tumor cells from four of these five patients also demonstrated significant increase in the number of TCR Vbeta gene families with restricted number of CDR3 size peaks and loss of the normal CDR3 size gaussian distribution pattern. These findings were observed in patients who experienced recurrence after allogeneic stem cell transplantation and also in those who had autologous stem cell transplant. They also were found in previously untreated myeloma patients. In all six patients, distinct TCR Vbeta recurring transcripts indicative of a T-cell clonal expansion were found in the vicinity of the tumor cells and either absent or detected at only a low frequency in the peripheral blood. Our results provide evidence for an in situ local T-cell clonal expansion in the vicinity of tumor cells and support the presence of specific T-cell/tumor cell interaction in myeloma.

Oligoclonal T cell expansions in atherosclerotic lesions of apolipoprotein E-deficient mice.

T cells are present in atherosclerotic lesions at all stages of development. They exhibit activation markers and are particularly prominent at sites of plaque rupture. This suggests that T-cell-mediated immune responses are involved in the pathogenesis of atherosclerosis. Antigen-specific T cells reactive with oxidized lipoproteins and heat shock proteins have been isolated from plaques, indicating that local activation and clonal expansion might occur. To analyze different stages of atherosclerosis, we have used a murine model. Targeted deletion of the apolipoprotein E gene results in severe hypercholesterolemia and spontaneous atherosclerosis, with lesions containing large numbers of T cells and macrophages. We have analyzed mRNA for T-cell antigen receptors (TCRs) from aortic fatty streaks, early fibrofatty plaques, and advanced fibrofatty plaques of such mice. Polymerase chain reaction amplification of complementarity-determining region 3 (CDR3 region) of TCRs was followed by spectratyping of fragment lengths. This analysis detected all types of variable (V) segments with a gaussian distribution of CDR3 in lymph nodes. In contrast, a restricted heterogeneity was found in atherosclerotic lesions, with expansion of a limited set of Vbeta and Valpha segments and a monotypic or oligotypic CDR3 spectrum in each lesion. Vbeta6 was expressed in all lesions; Vbeta5.2, Vbeta16, Valpha34s, and Valpha9, in the majority of lesions; and Vbeta6, Vbeta5.2, and Valpha34S, in lesions at all 3 stages of development. The strongly skewed pattern of the CDR3 region in the TCR is indicative of oligoclonal expansions of T cells and suggests the occurrence of antigen-driven T-cell proliferation in atherosclerosis.

Toxic effector molecules in the pathogenesis of immune-mediated disorders of the central nervous system.

A growing body of evidence supports the notion that inflammatory reactions in the central nervous system (CNS) are not only restricted to established immune mediated disorders, such as multiple sclerosis, but also contribute to the pathogenesis of Alzheimer's disease and other types of neurodegenerative disorders. The biological roles of toxic mediators, such as nitric oxide, reactive oxygen species, as well as complement and proteases in the genesis of inflammatory reactions in the CNS are reviewed within the context of demyelination and neuronal damage.

Evidence for Preferential T Cell Receptor Vβ Gene Usage and T Cell Clonal Expansion in the Synovium of BB Rats with Early-Onset Collagen-Induced Arthritis

Type II collagen (CII) is a potent arthritogen in the BB rat. To determine whether a restricted group of T cells is involved in the pathogenesis of collagen-induced arthritis, lymphocytes from synovium, peripheral blood, and lymph nodes of arthritic rats were studied for T cell receptor (TCR) Vβ gene usage using polymerase chain reaction (PCR). Oligoclonal TCR Vβ usage was found only insynovium recovered day 2 post-arthritis onset, but not day 7; lymph node and peripheral blood T cells showed diverse TCR usage at both times. To determine whether T cell local clonal expansion occurred in synovium at day 2 of arthritis, cDNAfor four TCR β families was sequenced through VDJ regions. Strong selective expansion of TCR Vβ 8.2,4, and 17 was noted. Importantly, the dominant clonotype of Vβ 8.2 was identical to that of a lymph node-derived T hybridoma specific for the immunodominant epitope in CII(181–210). Cells from synovium (day 2 postonset) analyzed by flow cytometry also showed Vβ 8.2+cell enrichment. These observations, plus finding that T cells from inflamed synovium respond to CII(181–201)in vitro,suggest the local recruitment and clonal expansion of some T cells families, possibly driven by autologous CII released during cartilage degradation.

Analysis of the T-cell receptor repertoire in human atherosclerosis.

Analysis of T-cell receptor (TCR) beta-chain gene expression in atherosclerotic lesions of human aorta. TCR diversity was studied using non-radioactive polymerase chain reaction for quantitative assessment of TCRBV gene transcripts, together with size and sequence analysis of the beta-chain third complementarity-determining region (CDR3). Samples represent a wide range of atheromatous histology, allowing evaluation of the T-cell repertoire at different stages of disease. Diverse TCRBV family usage was observed in the majority of the samples, as the 25 different TCRBV products were detected at levels exceeding background. The data also showed that TCRBV transcripts expressed in the diseased aorta tissue displayed considerable size heterogeneity and no repetition of CDR3 nucleotide motifs. The early presence of T-lymphocytes in the atheromatous blood vessel has been interpreted as an indication of specific immunological reactions operating during the course of the atherosclerotic process. Although a T-cell infiltrate characterized by limited usage of TCRAV genes cannot be excluded the unrestricted usage of TCRBV genes argues against a local T-cell clonal expansion in atherogenesis.

Regulation of T-cell activation in the lung: isolated lung T cells exhibit surface phenotypic characteristics of recent activation including down-modulated T-cell receptors, but are locked into the G0/G1 phase of the cell cycle.

Peripheral lung tissue contains large numbers of T cells, strategically located for immune surveillance at the blood-air interface. Given the intensity of antigenic exposure at this site, it is clear that local T-cell activation events require strict control, in order to maintain tissue homeostasis. How this control is achieved in this unique tissue microenvironment is unknown, and the present study sought to elucidate the process via detailed analysis of the surface phenotypic characteristics of freshly isolated lung T cells. We report below that these cells display typical characteristic of 'postactivation', notably elevated basal Ca2+ concentrations, down-modulated T-cell receptors, expression of Ia and 'late' activation antigens and concomitant CD4/CD8. However, levels of interleukin-2 receptor and CD2 expression were below those expected of 'activated' T-cell populations, and virtually all of the cells were found to be in the G0/G1 phases of the cell cycle. These properties bear a remarkable similarity to those of T cells activated in the presence of endogenous tissue (alveolar) macrophages from the lung (see accompanying paper). We hypothesize that they reflect the in vivo operation of an endogenous macrophage-mediated T-cell anergy-induction process, the function of which is to limit the local clonal expansion of T cells in peripheral lung tissue after in situ activation.

T cell receptor repertoire of T lymphocytes recovered from the lung and blood of patients with sarcoidosis.

We evaluated the repertoire of V beta segments used in forming the T-cell receptor of lavage and blood T lymphocytes from 11 sarcoid patients and 10 normal subjects using procedures based on quantitative polymerase chain reaction, permitting analysis of both the abundance of transcripts using each of 20 different V beta families and the diversity of the VDJC beta rearrangements within each V beta family. Blood and lung T cells from sarcoid patients had a very diverse V beta repertoire. For all V beta families but one, the abundance of the V beta transcripts fell within the mean +/- 2 SD of that observed for normal blood lymphocytes; no difference in the overall abundance was observed comparing lavage and blood T cells, and the length of VDJC beta rearrangements for a given V beta family in samples from sarcoid patients was usually quite heterogeneous. Despite the overall polyclonality, evidence for selective expansion of T cells was found, in that an increased abundance of V beta 19 transcripts was observed for sarcoid blood and/or lung T cells in eight out of 11 patients studied, and rearrangements of a single predominant length using certain (e.g., V beta 19, V beta 14), but not all, V beta families were present. Sequencing confirmed the presence of a single predominant VDJC beta rearrangement in these cases. These findings suggest that the alveolitis in sarcoidosis results from two distinct processes, a local clonal expansion of T cells associated with an apparently nonspecific accumulation of T cells with an extremely diverse V beta repertoire.

Regional heterogeneity in the DNA content of human gliomas.

Regional heterogeneity causes significant errors in the histologic classification and grading of gliomas, but little is known about its implications for other modalities. Attempts to predict glioma behavior using flow cytometry (FCM) have yielded contradictory results, possibly due to regional heterogeneity in DNA content, a recognized phenomenon that has not been evaluated systematically. The authors used FCM to analyze the DNA content of 353 regions from 18 resected human gliomas. Five to 60 regions were sampled from each tumor, and the topographic relationships of ploidy, proliferative activity (S-phase fraction [SPF]), and histologic features were established. Most tumors demonstrated heterogeneity among regions in the number and relative sizes of aneuploid populations and/or proliferative activity. The degree of heterogeneity increased with tumor grade. Heterogeneity in histologic features, ploidy, and proliferative activity appeared to vary independently, except for a significant association between the presence of mitotic figures and the SPF of individual regions (P < 0.0001). The clustering of regions with similar percentages of aneuploid cells supported the concept of local clonal expansion. Gliomas express significant regional heterogeneity in ploidy and proliferative activity and this will have an adverse effect on the usefulness of their analysis. However, the independent variation of ploidy, proliferative activity, and histologic features suggests that the use of multiple analyses may allow more accurate prediction of glioma patient survival. Regional heterogeneity appears be a fundamental property of malignant gliomas; systematic studies to determine its effects on the diagnostic usefulness of other new methods used to evaluate gliomas are indicated.