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Morphological manifestations of acute colitis and subpopulation composition of colon lymphocytes were studied in male and female C57Bl/6 mice with acute dextran-induced colitis. We evaluated the severity of colitis symptoms, morphological changes in the colon, and prevalence of epithelialized and non-epithelialized ulcers. The subpopulation composition of lymphocytes (CD3—CD19+ B cells, CD3+CD4+ T helpers, CD3+CD8+ cytotoxic T cells, and CD4+CD25+FOXP3+ regulatory T cells) was assessed by flow cytofluorometry in suspension of colon cells prepared by enzymatic disintegration. In males, clinical manifestations of acute colitis and morphological changes were more severe and the prevalence of non-epithelialized ulcers was higher than in females. In females, the content of T, B, and regulatory T cells in the colon wall was higher, while the content of cytotoxic T cells was lower than in males. In females with acute colitis, the absolute lymphocyte count and the content of B cells and regulatory T cells decreased, while the percentage of cytotoxic T cells increased in comparison with intact animals. In males with acute colitis, the levels of regulatory T and B cells increased in comparison with the corresponding parameter in intact animals. Morphological changes and changes in the lymphocyte subpopulations, detected in males and females with acute colitis, were determined by different levels of sex steroid hormones. [ABSTRACT FROM AUTHOR]

Multiple sclerosis is an inflammatory T cell-mediated autoimmune disease. In a Phase II clinical trial, high-dose immunosuppressive therapy combined with autologous CD34+ haematopoietic stem cell transplant resulted in 69·2% of subjects remaining disease-free without evidence of relapse, loss of neurological function or new magnetic resonance imaging (MRI) lesions to year 5 post-treatment. A combination of CyTOF mass cytometry and multi-parameter flow cytometry was used to explore the reconstitution kinetics of immune cell subsets in the periphery post-haematopoietic cell transplant (HSCT) and the impact of treatment on the phenotype of circulating T cells in this study population. Repopulation of immune cell subsets progressed similarly for all patients studied 2 years post-therapy, regardless of clinical outcome. At month 2, monocytes and natural killer (NK) cells were proportionally more abundant, while CD4 T cells and B cells were reduced, relative to baseline. In contrast to the changes observed at earlier time-points in the T cell compartment, B cells were proportionally more abundant and expansion in the proportion of naive B cells was observed 1 and 2 years post-therapy. Within the T cell compartment, the proportion of effector memory and late effector subsets of CD4 and CD8 T cells was increased, together with transient increases in proportions of CD45RA-regulatory T cells (Tregs) and T helper type 1 (Th1 cells) and a decrease in Th17·1 cells. While none of the treatment effects studied correlated with clinical outcome, patients who remained healthy throughout the 5-year study had significantly higher absolute numbers of memory CD4 and CD8 T cells in the periphery prior to stem cell transplantation. [ABSTRACT FROM AUTHOR]

Hepatitis C virus (HCV) infection leads to liver injury, which is thought to be immune-mediated. Apoptosis of hepatic T cells could influence histological damage. We quantified peripheral and intrahepatic T-cell apoptosis in 28 patients with chronic hepatitis C by using cytofluorometric techniques. METAVIR score and HCV plasma viral load were determined. Six liver biopsies, obtained from controls without chronic hepatitis during hepatobiliary surgery, served as controls. In patients, liver T-cell apoptosis was upregulated compared to peripheral T cells: 35 versus 7% for CD4+ and 56 versus 13% for CD8+ T cells ( P < 0.001). Liver T-cell apoptosis levels from patients were increased compared to controls for both CD4+ ( P = 0.041) and CD8+ T cells ( P = 0.007). Nine patients exhibiting METAVIR scores A and F ≤1 showed higher intrahepatic CD4+ T-cell apoptosis compared to the 19 patients with a higher METAVIR score ( P = 0.001) and both histological activity and fibrosis were related to apoptosis level. There was also an inverse relationship between the level of intrahepatic CD8+ T-cell apoptosis and serum transaminase activity ( P = 0.023). Our study shows immune compartmentalization, suggesting that the study of peripheral blood lymphocytes may not be fully relevant to the pathophysiology of HCV hepatitis, and that the severity of liver injury is inversely correlated with intrahepatic CD4+ T-cell apoptosis. [ABSTRACT FROM AUTHOR]

Intestinal T cells have a unique state of activation and differentiation which might specifically affect or be affected by HIV infection. Lymphocyte subsets in the peripheral blood are well characterized, but our knowledge about intestinal lymphocytes in HIV infection is incomplete. We therefore analysed lymphocytes isolated from large intestine biopsies of AIDS patients and controls by three colour cytofluorometry. In the large intestine of HIV-infected patients CD4 T cells were reduced and CD8 T cells were increased compared with controls. Most of the CD8 T cells in the colorectal mucosa of AIDS patients were of the cytotoxic phenotype. Activated and resting CD4 T cells were similarly reduced, the expression of CD25 and HLA-DR of CD8 T cells was unaltered and increased, respectively. In intestinal CD4 T cells the expression of CD29 was decreased, but the expression of CD45RO and HML-1 was normal. CD8 T cells had a decreased expression of all these differentiation markers. Our findings demonstrate substantial alterations in subset distribution, activation, and differentiation of large intestine T cells, which may contribute to the secondary infections and malignancies commonly observed in the gut of AIDS patients. [ABSTRACT FROM AUTHOR]

We have recently demonstrated that human thymocytes can be induced to express interleukin 2 (lL-2) receptors and to synthesize IL-2. The present study shows that relatively immature T6+ human thymocytes as well as the more mature T3+ thymocytes could be induced to express functional IL-2 receptors when activated with either Concanavalin A (Con A), Con A and 12-0-tetradeciinoylphorboI 13-acetate(TPA) or IL-2 in combination with Con A or TPA. The phenotype of the common, immature thymocyte was identified by the binding of either fluorescein isothiocyanate (FITC)- or phycoerythrin (PE)-conjugated monoclonal anti-T6 (OKT 6) antibody and of mature thymocytes by the binding of monoclonal anti-T3 (OKT 3) antibody. We also observed that the expression of the T3 antigen on thymocytes, freshly isolated from thymic specimens obtained in the course of cardiac surgery of infants and children, was greater than 40% in i4 of 18 donors and that thymocytes co-expressed the T3 and the T6 antigen as determined by dual colour cytofluorometry. In thymocytes activated in vitro the expression of IL-2 receptors, determined by dual colour cytofluorometry with the PE-conjugated monoclonal anti-human IL-2 receptor antibody (PE anti-IL-2 R), was detected by the second day of induction in both immature T6+ and mature T3+ thymocytes, T6+ thymocytes proliferated In response to IL-2 and persisted in cultures for the duration of the study (18 days) and continued to express IL-2 receptors. [ABSTRACT FROM AUTHOR]

Rat monoclonal antibodies (mAb) against isolated pig Null T cells were derived using a novel twocolour cytofluorometric assay. One (MAC320) identified all blood CD2- sIg- 'Null' cells (present at up to ∼6 × 106/ml). Another type (MAC319 and MAC318) identified a subset comprising ∼60% or ∼30% of the Null cell population. This percentage appears genetically determined. This subset partially overlapped with a γδ T-cell receptor+ (TcR+) population which consisted of ∼40% of Null T cells. The antibodies did not react with other leucocyte or lymphocyte populations. In non-reducing conditions, MAC320 precipitated two molecules at ∼270,000-280,000 MW in SDS-PAGE; the larger of which was also precipitated by MAC319 (and MAC318, which binds to the same epitope). Under reducing conditions, MAC320 immunoprecipitated two or three polypeptide chains at ∼130,000-160,000 MW; MAC319 precipitated only the largest of these polypeptides, The large MAC319+ MAC320+ molecule on one subset is removed by bromelain treatment; the smaller MAC319- MAC320+ molecule on the remaining Null cells is not bromelain sensitive. Several properties of this new antigen complex specific to pig Null T cells show that it is distinct from the ruminant T19 complex. [ABSTRACT FROM AUTHOR]

Graft-versus-host disease (GVHD) due to allogeneic bone marrow transplantation can be prevented by depleting the T cells from the marrow graft in vitro. However, the elimination of the donor T cells results in a higher frequency of graft failure, secondary infections and, in case of leukaemia, relapse. We found, that, in contrast to normal spleen cells, spleen cells from A or B10 donor mice pretreated with xenogeneic antithymocyte serum (ATS) in vivo did not induce GVHD in non-irradiated (B10 x A)F1 hybrids. Spleen cells of ATS-pretreated A donors did not cause GVHD in allogeneic CBA mice made neonatally tolerant to the A donor strain either. Furthermore, spleen cells from ATS-treated donors did not cause GVHD in irradiated F1 hybrid recipients, moreover, they decreased the lethal effect of irradiation. The in vivo ATS pretreatment improved the repopulating capacity of spleen cells in irradiated syngeneic recipients, too. The effect of the ATS treatment does not rely solely upon the elimination of T cells, since flow cytofluorometric analysis revealed only a partial depletion of both the CD4+ and CD8+ T cells of the ATS-pretreated animals. These observations may also have clinical relevance. [ABSTRACT FROM AUTHOR]

Relative amounts of β2-microglobulin (β2m) and of HLA specificities were analysed on the surface of resting unfractionated peripheral human lymphocytes, enriched B and T cells, and on in-vivo- and in-vitro-stimulated lymphoblasts. Single-cell cytofluorometry and a very sensitive radioimmunoassay were used to determine as closely as possible the absolute amounts of membrane-bound β ;2m/HLA antigens. B and T 'resting' and 'stimulated' lympboid cells express very similar numbers of β ;2m and HLA antigenic determinants, respectively, per unit of surface area when compared within each group, although β ;2m was found to exist in two- to three-fold excess of HLA. [ABSTRACT FROM AUTHOR]

The authors devised a cytotoxic assay based on cytofluorometric analysis of target surface markers in order to compare lysis exerted in vitro by cytotoxic T lymphocytes (CTLs) on different cell subsets in the context of a single lymphoid target cell population. Using this assay, the authors evaluated when oncoma virus-infected lymphocytes become a suitable target for virus-specific T cell effectors. A lymphocyte population from Moloney-murine leukaemia virus (M-MuLV)-infected (carrier) mice, in which the proliferation of selective Vβ T-cell receptor (TCR) families was induced in response to Mlsa encoded antigens, was utilized as a target. The authors observed that a virus-specific T cell clone exerted lytic activity preferentially against activated cell subsets. Moreover, virus-specific CTLs generated in mixed leucocyte tumour cell cultures (MLTC) were also able to impair the concomitant anti-Mlsa response of lymphocytes from M-MuLV carrier mice. It was found that the proliferative status of oncorna virus-infected target cells played an important role in limiting the in vitro efficacy of the immune response, and it is speculated that this phenomenon might represent an in vivo escape mechanism from immunosurveillance. [ABSTRACT FROM AUTHOR]

The distribution of T-helper cell subsets of human umbilical cord lymphocytes was compared with that of adult peripheral blood lymphocytes. Cytofluorometric analysis revealed a similar Leu 3/Leu 2 (helper/suppressor) ratio in neonates compared with adults. Total T-cell numbers were slightly decreased in neonatal blood. The Leu 3-positive-4B4-positive cell (helper-inducer) subset, however, was markedly reduced in neonatal blood, while the Leu 3-positive-2H4-positive cell (suppressor- inducer) subset was increased compared with that of normal adults. These findings may contribute to the poor help and enhanced suppression observed in vitro with neonatal T cells. [ABSTRACT FROM AUTHOR]