Lymphocyte activation in rheumatoid arthritis synovial fluid in vivo

Tracking Dye-Independent Approach to Identify and Isolate In Vitro Expanded T Cells

T cell proliferation is routinely identified in vitro using tracking dyes or through detecting intracellular upregulation of the nuclear protein, Ki-67. However, labeling with tracking dyes is cumbersome, associated with cellular toxicity, while Ki-67 cannot be used to identify and isolate viable T cells, and both techniques are incompatible with MACS technology. Here, we introduce a simple tool to identify and isolate in vitro T cell expansion that is tracking dye-independent and allows for sorting of viable T cells. We show that CD71, a transferrin receptor, and CD98, a heterodimer glycoprotein involved in both integrin signaling and amino-acid transport, are both highly upregulated on proliferating T cells upon in vitro stimulation, and that CD71 expression is maximal on the more recent progeny T cells, while CD98 upregulation remains stable across different generations of progeny T cells. Moreover, we demonstrate that the upregulation of CD71 and CD98 identifies CFSE^low T cells and provides further proof of the antigen-specificity of T cells identified by CD71 and CD98 dual upregulation based on tetramer staining. We further show that CD71 can be used to enrich for in vitro expanding T cells using MACS technology. In conclusion, we show that CD71 and CD98 can be used to identify and isolate expanded T cells following in vitro stimulation and that CD71 is an MACS-compatible alternative to tracking dyes or Ki-67 detection. © 2019 International Society for Advancement of Cytometry.

CD98 at the crossroads of adaptive immunity and cancer

Adaptive immunity, a vertebrate specialization, adds memory and exquisite specificity to the basic innate immune responses present in invertebrates while conserving metabolic resources. In adaptive immunity, antigenic challenge requires extremely rapid proliferation of rare antigen-specific lymphocytes to produce large, clonally expanded effector populations that neutralize pathogens. Rapid proliferation and resulting clonal expansion are dependent on CD98, a protein whose well-conserved orthologs appear restricted to vertebrates. Thus, CD98 supports lymphocyte clonal expansion to enable protective adaptive immunity, an advantage that could account for the presence of CD98 in vertebrates. CD98 supports lymphocyte clonal expansion by amplifying integrin signals that enable proliferation and prevent apoptosis. These integrin-dependent signals can also provoke cancer development and invasion, anchorage-independence and the rapid proliferation of tumor cells. CD98 is highly expressed in many cancers and contributes to formation of tumors in experimental models. Strikingly, vertebrates, which possess highly conserved CD98 proteins, CD98-binding integrins and adaptive immunity, also display propensity towards invasive and metastatic tumors. In this Commentary, we review the roles of CD98 in lymphocyte biology and cancer. We suggest that the CD98 amplification of integrin signaling in adaptive immunity provides survival benefits to vertebrates, which, in turn, bear the price of increased susceptibility to cancer.

Shigella infection induces cellular activation of T and B cells and distinct species-related changes in peripheral blood lymphocyte subsets during the course of the disease

Immunophenotypic changes in peripheral blood lymphocytes (T, B, and NK cells) in patients during shigellosis was characterized by using triple-color flow cytometry. Eleven Shigella dysenteriae 1-infected adult patients (SDIP), 11 Shigella flexneri-infected adult patients (SFIP), 15 age- and sex-matched healthy controls from Bangladesh (C-B), and 15 healthy volunteers from Sweden (V-S) were studied. In SDIP and SFIP, a significant increase in the CD45RO+ cells in both CD4+ and CD8+ T cells were seen. We found evidence for sequential T-cell activation, as shown by increased proportions of CD25 and CD4+ cells; HLA-DR and CD38 on CD8+ cells, and CD54 on CD4+ and CD8+ cells. We found differences in the lymphocyte activation and subset patterns related to the infecting Shigella species. Thus, a decrease in CD45 expression was seen in SFIP; this decrease progressed further during the disease. The proportions of NK cells (CD56+ cells) and CD3- CD8+ cells out of the total CD8+ cells were increased in SFIP but not in SDIP. The CD3+ CD8+ CD57+ T-cell subset was significantly lower in SDIP than in C-B. The proportion of B-lymphocyte-expressing activation markers CD80 and CD23 was higher in patients than in C-B. There was a significant increase in the proportion of CD4+ T cells and a significant decrease in the percentages of total B cells, the CD3+ CD8+ CD57+ T-cell subset, and the CD56+ CD16+ NK-cell subset for V-S compared with C-B. Our results indicate that distinct subset changes and activation patterns are elicited in SDIP compared with SFIP and also that the degree of activation is related to disease severity. In addition, a common sequence of cell activation was seen during the disease course. The difference in the subset patterns seen in C-B and V-S may be related to differences in the levels or spectra of infectious agents in the environment.

Oligoclonal T cells in rheumatoid arthritis: identification strategy and molecular characterization of a clonal T-cell receptor

Immunodominant antigens in rheumatoid arthritis (RA) should induce an expansion of T cells bearing a corresponding T-cell receptor (TCR). We therefore analysed the TCR repertoire at the site of inflammation using two fundamentally different strategies. The total TCR repertoire was examined by generating 'representative' T-cell clone panels, which were subsequently tested for clonality by restriction mapping of the TCR beta gene locus. No clonality was detected in large T-cell clone panels generated with cells from three patients. However, when we selectively analysed the TCR repertoire of in vivo pre-activated, interleukin-2 (IL-2)-responsive T cells, significant T-cell/TCR clonality was found in 2 out of 4 patients. The clonal T cells represented a minority of the total T-cell population with an estimated frequency of 1 in 300 to 1 in 1000 cells. Molecular characterization of a clonal TCR and the use of a specific TCR V beta MoAb ruled out an over-representation of T cells bearing the same V beta element in the total T-cell population, rendering the involvement of super-antigens in the induction of T-cell clonality in this case unlikely.

T lymphocyte adhesion to fibronectin (FN): a possible mechanism for T cell accumulation in the rheumatoid joint

The accumulation of T cells within the joint is responsible for the perpetuation of synovitis. This process is partly regulated by selective binding to endothelium. However, adhesion to extra-cellular matrix proteins, like FN, may also be important. FN binding is mediated by certain members of the VLA (beta 1 integrin) family of proteins. To investigate the role of Tc-FN interactions in synovitis the binding of synovial fluid (SF) and peripheral blood (PB) T cells to FN-coated wells, and the expression of cell surface VLA molecules on these cells by double label immunofluorescence, were studied. SF T cells bound better to FN than PB T cells. VLA alpha 4 and VLA beta 1 but not VLA alpha 5 were up-regulated on SF compared with PB T cells. Anti-VLA alpha 4, VLA beta 1 and VLA alpha 5 MoAbs inhibited the binding of SF T cells to FN. The increased binding of SF T cells to FN could have been related to activation and/or to their predominantly memory phenotype. Purified resting memory or naive T cells bound poorly to FN. In contrast, compared with SF T cells, concanavalin A-activated T cells showed a very similar level of binding to FN, comparable expression of VLA molecules and the same pattern of inhibition of binding to FN by MoAbs. Thus, VLA molecules may play an important role in the retention of T cells in the joint and since T cells can be activated via VLA-FN interactions, this mechanism may perpetuate chronic inflammation.

Are lymphocytes a target for substance P modulation in arthritis?

The contribution of the neuropeptide substance P to the pathogenesis of rheumatoid arthritis (RA) has recently been suggested. The presence of immunoreactive substance P in the serum and joint fluid of RA patients was significantly increased compared with age-matched control patients. To investigate the ability of substance P to alter lymphocyte activity during the disease, lymphocytes were isolated from the synovial fluid and blood of RA patients and their ability to respond to substance P as measured by [3H]thymidine uptake was characterized. Upon exposure of RA synovial fluid and peripheral blood lymphocytes to various concentrations of substance P in vitro, no increase in proliferation was witnessed. To the contrary, control peripheral blood lymphocyte proliferation was significantly enhanced by various concentrations of substance P. However, synoviocytes from the joints of RA patients were responsive to substance P stimulation. These data suggest that substance P receptors may be desensitized on systemic and local lymphocytes in RA, or the proinflammatory activities of substance P may be mediated via the synovial membrane during chronic inflammation.

Selective migration of the human helper-inducer memory T cell subset: confirmation by in vivo cellular kinetic studies

The vast majority of T cells present in chronic inflammatory lesions are of the helper-inducer/memory (CD45RO+CD29+) phenotype; suppressor-inducer/naive cells (CD45RA+) are virtually absent. Furthermore, CD4+ T cells are found more frequently than CD8+ cells. Previous in vitro studies have suggested that this may be, in part, due to the increased capacity of CD45RO+CD29+ T cells to bind to endothelium and, thus, enter inflammatory foci but no in vivo evidence for preferential migration exists. To investigate this, suction blisters were generated over a purified protein derivative of tuberculin-induced delayed-type hypersensitivity lesions in humans and the phenotype of the blister cells was studied. At all time points, a preponderance of CD45RO+CD29+ cells over CD45RA+ cells and of CD4 over CD8 cells was demonstrated. Because of the rapid kinetics, this appears to represent preferential migration of these cell types rather than in situ proliferation or phenotype conversion. In addition the expression of the CD45RO but not the CD45RA antigen was up-regulated on blister T cells compared to blood T cells. Analysis of blister fluid showed high concentrations of interleukin 6 but not tumor necrosis factor-alpha or lymphotoxin. This study shows for the first time directly in vivo that CD45RO+ T cells migrate preferentially into inflammatory lesions. Furthermore, it illustrates the potential usefulness of this system in the analysis of the early phases of the immune inflammatory response.

Chemoattractant production by synovial fluid cells in chronic arthritis. A study with a new double-chamber method for quantitating the motility of mononuclear cells labelled with chromium-51

A new method was developed to study the migration of lymphocytes under in vitro conditions. Attractant fluid was added to the appropriate lower wells, which were filled to the brim. Peripheral blood mononuclear cells were labelled with 51Cr and then put into the upper wells. Surface tension and capillary force are enough to make clamping of these plates possible, separated by a polycarbonate filter, 15 microns thick with a pore size of 8 microns, between these two standard multiwell microculture plates. After three hours of incubation at +37 degrees C in a humidified 5% CO2 atmosphere, the migrated cells were harvested from the lower wells using a semiautomatic harvester, and the radioactivity was counted. The present method makes it unnecessary to enrich or select for different cell subsets for migration studies. Instead, density gradient separated mononuclear cells as such can be used to assess their migratory capacity.

T cell receptor expression and activation of synovial lymphocyte subsets in patients with rheumatoid arthritis. Phenotyping of multiple synovial sites

Two-color flow cytometry analysis of peripheral blood and synovial lymphocytes from rheumatoid arthritis patients was performed using monoclonal antibodies directed against T cell subsets, T cell activation markers, and T cell receptors. The results showed an abnormally high percentage (greater than 15%) of CD3+, CD4-, and CD8- T cells expressing a specific receptor containing a gamma chain. Phenotypic analysis of lymphocytes infiltrating both knee joints of individual rheumatoid arthritis patients revealed very similar subset distribution and activation levels, despite strong differences in the clinical status between the 2 sites.

Expression of activation antigens on T cells in rheumatoid arthritis patients

The aim of our study was to identify differences in cell surface marker expression between T cells taken from the peripheral blood (PB) of healthy individuals and T cells recovered from inflamed joints of rheumatoid arthritis (RA) patients. Out of 118 monoclonal antibodies (MoAbs) directed against activation antigens on haematopoietic cells, 12 MoAbs recognizing nine distinct surface molecules were selected after a screening procedure to study the expression of the corresponding antigens on T cells from the PB, synovial fluid and synovial tissue of RA patients, and also on T cells from PB and spleens of controls. Using two-colour flow cytometry and immunohistology we found the molecules B-C5, CD39, CD40, CD45 R0, CD54, CD76 and potentially 1D11 to be substantially up-regulated on T cells from various body compartments in RA patients. We thus could determine that the cell surface of T cells in RA patients not only differs in MHC class II expression, but also in a number of other activation-associated cell surface molecules from T cells in healthy individuals.

Soluble interleukin 2 receptor molecules in the serum of patients with autoimmune diseases

Lymphocytes upon activation release a soluble form of interleukin 2 receptor (IL-2R). Systemic autoimmune disorders are characterized by immune system disregulation associated with cellular activation; therefore we sought to determine the levels of soluble IL-2R molecules in the serum of patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and primary Sjogren's syndrome (1 degree SS). Utilizing an enzyme immunoassay method we found increased serum levels of soluble IL-2R in 65.4% (34/52) of RA, in 34.9% (15/43) of SLE, and in 25.0% (13/52) of 1 degree SS patients, compared to 4.2% (1/24) of healthy individuals. High serum levels of soluble IL-2R correlated with several indices of disease activity in RA and SLE patients, as well as with disease progression to extraglandular involvement and to pseudolymphoma or lymphoma in patients with 1 degree SS. By gel filtration analysis, the soluble IL-2R circulating in the serum of a RA patient corresponded to a high molecular weight molecule (greater than 90 kDa) compared to the 65-kDa soluble IL-2R molecule released by phytohemagglutinin-stimulated normal peripheral lymphocytes.

The preferential accumulation of helper-inducer T lymphocytes in inflammatory lesions: evidence for regulation by selective endothelial and homotypic adhesion

The mechanisms which lead to the accumulation of T lymphocytes into inflammatory lesions are not clearly understood. We have previously shown that synovial CD4 T lymphocytes are mostly CDw29+UCHL1+ (helper-inducer cells) and very few carry the CD45R antigen which identifies the suppressor-inducer subset. Synovial CD8+ cells are also CDw29+UCHL1+CD45R-. In the present study, lymphocytes from pleural and peritoneal inflammatory infiltrates were shown to have a similar phenotypic pattern. Furthermore, it was demonstrated that the CDw29+UCHL1+ subset had a greater ability than CD45R+ cells to adhere to endothelial cells and to form homotypic clusters. Differential surface expression of LFA-1 on the two subsets was also shown, but this could not account for the demonstrated adhesion differences. Differences in adhesion between CDw29+/UCHL1+ and CD45R+ cells may explain the preferential accumulation of CDw29+/UCHL1+ cells in inflammatory infiltrates and underlie some of the functional differences between cells taken from sites of chronic inflammation and those from peripheral blood.

Abnormal helper-inducer/suppressor-inducer T-cell subset distribution and T-cell activation status are common to all types of chronic synovitis

We have previously shown that rheumatoid synovial T cells are virtually all helper-inducer (CD4+4B4+UCHL1+) rather than suppressor-inducer (CD4+2H4+) cells. CD8 cells were also largely 4B4+. In addition, the majority of T cells were HLA-DR+. To investigate whether these findings were specific for rheumatoid disease, we studied the prevalence of these markers in a variety of chronic inflammatory arthropathies such as ankylosing spondylitis, Reiter's syndrome, and psoriatic arthritis. Again, almost 90% of the T cells were 4B4+UCHL1+ and only 11% were 2H4+; 50% expressed the HLA DR antigen. Thus this phenotypic distribution represents a final common pathway of chronic synovitis and may help to explain the immunopathology of the lesion.

Synovial fluid lymphocytes in different subtypes of juvenile rheumatoid arthritis

We studied the subsets of synovial fluid (SF) lymphocytes and their activation states in 4 subtypes of juvenile rheumatoid arthritis. The expression of lymphocyte differentiation antigens and activation markers (Ia and Tac) appeared to be similar in these subgroups. Tac + DNA-synthesizing T blasts represented, at most, 5% of all SF mononuclear cells. This finding was in clear contrast to the high proportion of Ia-positive SF mononuclear cells. There were no differences in Ia and Tac expression or DNA synthesis among the different juvenile rheumatoid arthritis subgroups. This finding suggests that the cell-mediated immune response may represent secondary features of the disease that are involved as a final common pathogenetic pathway.

T cell subsets in the blast cell population in phytohemagglutinin-stimulated peripheral blood in vitro and in rheumatoid arthritis synovial fluid in vivo

The immunomodulatory T4/T8 ratio was studied in the total and activated lymphocyte populations by a method combining visualisation of 3H-thymidine incorporating blasts with autoradiography (AR) with simultaneous identification of the respective lymphocyte subsets using monoclonal antibodies in avidin-biotin-peroxidase complex (ABC) staining. In rheumatoid arthritis synovial fluid the activated T4/T8 ratio (calculated from T cells in the S phase of the cell cycle) was significantly different from the total T4/T8 ratio (calculated for all the T cells) (0.45 +/- 0.05 versus 0.69 +/- 0.05, P less than 0.01). Similarly, the activated and total T4/T8 ratios were also significantly different in the phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cell cultures at days 3 and 5.

Activation marker analysis of mononuclear cell infiltrates of oral lichen planus in situ

Monoclonal activation markers (Ia, Tac, T9, and 4F2) were used to detect the degree of activation of mononuclear cells in the inflammatory infiltrates of oral lichen planus in situ. In addition the specimens were stained with the following monoclonal antibodies: T4, T8, T11, M1, and pan-B. T-lymphocyte was the predominant cell type in the inflammatory infiltrates. According to the results of the activation marker analysis, the majority of the T-lymphocytes were resting. However, activated cytotoxic T8 and 4F2 T-cells were located close to damaged basal cells; this finding may suggest that they are responsible for the damage and supports the claim that a cell-mediated immune response participates actively in local pathogenetic mechanisms in oral lichen planus.

Lymphocyte subpopulations, activation phenotypes, and spontaneous proliferation in tuberculous pleural effusions

The state of lymphocyte activation in tuberculous pleural effusions was studied. The proportion of cells at and beyond the G1 phase of the cell cycle displaying interleukin-2 receptor, transferrin receptor or gp 40/80 glycoprotein in avidin-biotin-peroxidase complex (ABC) staining was 6 +/- 2 percent, 8 +/- 3 percent, and 14 +/- 4 percent of all pleural fluid mononuclear cells, respectively. These findings imply that only a fraction of pleural fluid lymphocytes is activated in tuberculosis. The proportion of autoradiographically visualized 3H-thymidine incorporating blasts at the S phase of the cell cycle was 1.2 +/- 0.3 percent. This phenomenon further confirms the impression that, in spite of activation, most of the pleural fluid mononuclear cells are resting cells. The T4/T8 ratio in the functionally active blast cell population determined by a double labeling method combining ABC staining with autoradiography was similar to the total T4/T8 ratio (2.3 +/- 0.7 vs 2.7 +/- 0.8, p greater than 0.05) calculated for all pleural fluid mononuclear cells.

Phenotypes of T lymphocytes from peripheral blood and synovial fluid of patients with rheumatoid arthritis and juvenile rheumatoid arthritis. Evidence in favour of normal helper and suppressor functions of T lymphocytes from patients with juvenile rheumatoid arthritis

Lymphocytes from peripheral blood (PB) and synovial fluid (SF) from 21 patients with rheumatoid arthritis (RA) and 18 patients with juvenile rheumatoid arthritis (JRA) were studied with respect to T cell phenotypes using monoclonal antibodies in a rosette assay. The percentage of HLA-DR positive T cells was counted in PB and SF using indirect immunofluorescence. Suppressor cell activity of T cells from PB and SF was investigated by measuring the immunoglobulin production by pokeweed mitogen (PWM) stimulated B cells mixed with T cells at various ratios. The mean T4/T8 ratio was significantly lower in SF than in PB of both RA and JRA patients (p = 0.0062 and p less than 0.0001 respectively). The mean percentages of HLA-DR positive T cells were elevated in SF compared with PB in both patients groups (p less than 0.03 and p less than 0.04 in RA and JRA patients respectively). Mean suppressor cell activity and helper cell activity of T cells from SF and PB of JRA patients was normal. Thus there seems to be a dichotomy between the number of T8+ cells and suppressor cell function in mononuclear cells from SF of patients with JRA. This indicates that a considerable proportion of the T8+ cells in the SF do not have suppressor functions.

Expression of MHC class II antigen, interleukin-2 receptor, transferrin receptor and gp 40/80 glycoprotein during different phases of a normal PHA-driven lymphocyte activation in vitro

This study characterizes the temporal profile of MHC class II antigen, interleukin-2 receptor, transferrin receptor and gp 40/80 glycoprotein lymphocyte activation markers in relation to each other during different phases of PHA-dependent cellular activation in vitro. Binding of these monoclonal lymphocyte activation-probes was visualized by the avidin-biotin-peroxidase complex method. Maximum PHA-dependent MHC class II antigen expression of 27 +/- 3% was observed on culture day 1, but later no significant differences were observed in MHC class II antigen expression between PHA-driven or culture media-containing control cultures. On the contrary, interleukin-2 receptor (78 +/- 6%) and transferrin receptor (75 +/- 5%) expression reached a maximum on culture day 3, coinciding with a maximum proliferative response. On culture day 5, when 3H-thymidine incorporation was already on the decline, gp 40/80 glycoprotein reached a maximum PHA-dependent expression of 78 +/- 2%, which differed significantly from interleukin-2 receptor (60 +/- 8%, p less than 0.05) and transferrin receptor (51 +/- 8%, p less than 0.01) expression. This study suggests that MHC class II antigen, interleukin-2 receptor, transferrin receptor and gp 40/80 glycoprotein, although all of them are lymphocyte-activation markers, differ as to the chronological sequence of their appearance and disappearance. Their combined use in lymphocyte-activation marker profile assay therefore gives valuable information about the lymphocyte activation state.

Phenotypic in situ characterization of lymphocytes in mild alcoholic liver disease

The subsets and expression of activation markers of inflammatory mononuclear cells in mild alcoholic liver disease were studied using monoclonal antibodies and an avidin-biotin-peroxidase complex (ABC) method. There were few B cells and monocytes in situ. Most of the mononuclear cells were of T cell origin, T4 and T8 positive cells being evenly distributed in a ratio of 2 to 1. This contrasts with the present and earlier findings on autoimmune liver diseases. The frequency of Ia (HLA-DR) positive cells varied between 15 and 30% of all mononuclear cells, which indicates activation of the local T cells. This implies that T cells in alcoholic fatty liver are not innocent bystanders but actively participate in the local inflammatory process. Staining for Tac, 4F2 and T9 was completely negative, however. These findings suggest that the local T cell activation may be incomplete and that it is not as extensive as in autoimmune liver diseases.