Distinct classes of human T-cell activation antigens

Flow cytometry as a method for studying effects of stressors on primary rat neurons

The mechanisms associated with cell death have been an important focus for neurobiology research. In the present study, the methodology of flow cytometry was used to optimize quantification of the toxic effects of tumor necrosis factor-alpha (TNF-alpha), trans-4-hydroxy-2-nonenal (4-HNE), and aged amyloid-beta (Abeta1-42) on rat primary cortical neurons. The fluorescent dyes annexin V-FITC and propidium iodide (PI) were used to identify populations of viable, early apoptotic, necrotic and late apoptotic cells by flow cytometry. Prior to exposure, the primary cultures showed 83% cell viability. Flow cytometry following labeling of cells with a specific neuronal marker, TUJ-1, revealed 82% pure neuronal populations, whereas approximately 7% were astrocytic as shown by glial fibrillary acidic protein positivity. Exposure of primary cultures to TNF-alpha, 4-HNE, and aged Abeta1-42 gave an increased number of early apoptotic cells. We show that flow cytometry is a suitable method for quantifying effects of different stressors on neurons in primary cultures. This technique could be useful for screening and testing of pharmacological compounds relevant to neurodegenerative disorders.

The immune system in hereditary hemochromatosis: a quantitative and functional assessment of the cellular arm

The objective of this investigation was to evaluate certain quantitative and functional characteristics of the effector cells of the cellular arm of the immune system in hereditary hemochromatosis (HH) with respect to treatment status. Two observations were consistent with the postulate that the elevated levels of storage iron has in vivo immunoregulatory properties: (1) the absolute number of CD8-positive T cells were significantly elevated in untreated HH patients (n = 7) and reduced in treated patients (n = 7), as compared with controls; and (2) the proliferative response of peripheral blood mononuclear cells from untreated HH patients to mitogens was suboptimal but the response of peripheral blood mononuclear cells (PBM) from treated HH patients was normal. Furthermore, immunoglobulin secretion by PBM from treated HH patients as compared to controls was altered. Finally, one T effector cell abnormality was unrelated to treatment status in that a subset of mature, non-activated T lymphocytes aberrantly formed thermostable erythrocyte-rosettes (TE-R), a lymphoid surface marker usually expressed on thymocytes or activated T cells. Taken together these data define certain immune alterations that are consistent with the interpretation that cellular immunity may be influenced by the high level of storage iron in HH patients.

Immunohistocytochemical correlation of DAP IV-CD 26 reactivity with immunologic markers of lymphocyte activation in human lymphoid tissues

The topographic distribution of the dipeptidylaminopeptidase IV (DAP IV-CD 26) and II (DAP II) positive T-cell population in six reactive lymph nodes and seven follicular B-cell non-Hodgkin's lymphomas (NHL) was analysed with regard to the distribution of activated T-cells, as visualized by a panel of monoclonal antibodies including Tac-CD 25, HLA-DR, OKT 9-CD 71, ICAM-1-CD 54, LFA-1-CD 11a. For comparative studies serial frozen sections of the lymph nodes were tested by enzyme histochemistry and immunohistochemistry. In addition, cell suspensions obtained from 10 B-NHL and interleukin-2 (IL-2) activated T-cells were investigated by a combined cytochemical and immunological method for simultaneous visualization of DAP IV-CD 26 cytoplasmic activity and surface immunostaining for markers of lymphocyte activation. Both in reactive and lymphomatous lymph nodes the topographic distribution of DAP IV-CD 26+ and DAP II+ lymphocytes was rather similar to that of Tac-CD 25+ lymphocytes. On the contrary, the DAP IV-CD 26 and DAP II distribution pattern substantially differed from that of the other immunologic markers. In a cell suspension of IL-2 activated T-cells, more than 80% of the cells with a blastic morphology were DAP IV-CD 26+; DAP IV-CD 26+ cells coexpressing Tac-CD 25, OKT 9-CD 71, HLA-DR positivity, relative to the total number of DAP IV-CD 26 positive cells, were 90.5%, 70.5% and 87% respectively. Only small (not activated) lymphocytes expressed a focal cytoplasmic DAP II positivity. In cell suspensions from 10 cases of B-NHL the mean percentage of DAP IV-CD 26+ Tac-CD 25+ cells was 75.8. Only a small number of DAP IV-CD 26+ cells coexpressed HLA-DR, the mean percentage being 9.6. The results support the view that DAP IV-CD 26 may be considered as a marker of lymphocyte activation; this marker seems to be restricted to T lymphocytes that reside in the T dependent areas of reactive lymph nodes and to non malignant T-cells surrounding neoplastic follicles of follicular NHL.

Identification and characterization of a novel membrane activation antigen with wide cellular distribution

A monoclonal antibody, 7F7, raised against the Raji B lymphoblastoid cell line reacted with about 35% of peripheral blood B cells, germinal center B cells, follicular dendritic cells and some vascular endothelial cells. Although not found on resting T cells this antigen was strongly expressed on CD4+ and CD8+ T cells activated with phytohemagglutinin, pokeweed mitogen and anti-T3, and its expression on B cells was enhanced after stimulation with pokeweed mitogen. It is strongly expressed 24 h after stimulation with phytohemagglutinin and its expression is reduced but not eliminated by cyclosporin A treatment. The molecule defined by antibody 7F7 is found on some, but not all, B cell lines, on an HTLV-I-transformed T cell line and on the promyelocytic cell line U937. Immunoprecipitation from externally and metabolically labeled Raji cells revealed a single-chain molecule of 85 kDa.

The immunoarchitecture of the normal human lacrimal gland. Relevancy for understanding pathologic conditions

To delineate the immunoarchitecture of the normal human lacrimal gland, monoclonal antibodies that detect B- and T-lymphocyte, macrophage, and dendritic cell lineage, subset, and differentiation-associated antigens were used in combination with highly sensitive tissue-section immunoperoxidase techniques. Plasma cells, identified with monoclonal antibody OKT10, represented the predominant mononuclear cell population, accounting for 53.9% of all mononuclear cells present. A qualitative study of plasma cell cytoplasmic immunoglobulin heavy-chain expression in deparaffinized, formalin-fixed tissue sections showed that the vast majority of these plasma cells contained IgA. Rare plasma cells contained IgG, IgM, or IgD. T-cells, identified with monoclonal antibody OKT3, represented the second most common cell type in the normal human lacrimal gland, accounting for 40.3% of all mononuclear cells present. T cells were located predominantly in lymphocytic foci and singly in the interstitium. T8 antigen-positive (suppressor/cytotoxic) T cells predominated over T4 antigen-positive (helper) T cells, averaging 25.2 and 14.7%, respectively. The overall mean T4/T8 ratio was 0.56. T8 antigen-positive T cells were the most numerous cell population outside aggregates and follicles, being distributed almost equally between the acini and the ducts (49%) and the interstitium (51%). Only 16% of T4 antigen-positive cells preferred glands or ducts to the interstitium. B cells, identified with monoclonal antibody BL9, represented only 5.7% of all mononuclear cells present. B cells were exclusively found in the centers of primary and secondary follicles. The majority of the surface immunoglobulin-positive B cells expressed IgM, fewer expressed IgD, and still fewer expressed IgG or IgA. Rare LeuM1+ OKM1+ macrophages were present in the center of B-cell follicles, where rare OKT6+ dendritic cells and activated T cells (IL-2+) were also discovered. These results support the concept that the lacrimal gland belongs to the mucosa-associated lymphoid system.

Distribution of natural killer cells and lymphocyte subclasses in Jessner's lymphocytic infiltration of the skin and in cutaneous lesions of discoid and systemic lupus erythematosus

We studied the cell infiltrates in biopsies from lymphocytic infiltration of the skin (LIS), with six monoclonal T cell antigen-specific antibodies and compared the reactivity pattern with those in biopsies from discoid and systemic lupus erythematosus skin lesions and allergic contact skin reactions. A newly described antibody (NK9) recognizing natural killer (NK) cells and activated cytotoxic T lymphocytes was included, and the numbers and activity of circulating NK cells was determined. Immunohistochemical staining revealed that the numbers of NK9-positive cells were highest in LIS. The distribution of T lymphocytes (OKTII + ve), helper T cells (OKT4 + ve), suppressor T cells (OKT8 + ve), Langerhans cells (OKT6 + ve) and activated T cells (anti-Tac + ve) in LIS differed from those in DLE,SLE and allergic contact reactions. However, the number of circulating NK cells (large granular lymphocytes) and the NK activity in peripheral blood were normal in LIS. We conclude that in LIS a distinct type of T cell activation occurs; the cause of this remains to be determined.

Lymphocytic subpopulations in the normal human conjunctiva. A monoclonal antibody study

Monoclonal antibodies were used to analyze the lymphocytic subpopulations in frozen tissue sections of normal human conjunctiva (epibulbar, tarsal, and forniceal). The overwhelming majority of lymphocytes were T-cells (Leu1+ and OKT8+). In the epithelium, the predominant cell type was the OKT8+ cytotoxic/suppressor cell, whereas in the substantia propria, helper T-cells (Leu3a/3b+) equalled suppressor T-cells. T-cells outnumbered B-cells 20-fold; the letter cells were detected only in the substantial propria, particularly in the fornices, and not in the epithelium. Plasma cells, as identified by OKT10 staining, were completely absent except in the accessory lacrimal glands of Krause. Langerhans' cells, identified by OKT6 and HLA-DR (la) staining, were observed in the epithelium of all conjunctival regions. Our findings suggest that the reactivity of B-lymphocytes and plasma cells is heavily damped down by T-lymphocytes, thus allying the conjunctiva to other mucosal membranes and the skin as heavily immunoregulated tissues.

Human tonsillar T lymphocytes: an immature or activated T-lymphocyte population

In this study we compare the phenotype and the enzyme content of T lymphocytes purified from tonsils and from circulating blood before and different times after in vitro activation with PHA. The phenotype was studied with the following panel of monoclonal antibodies for the presence of activation antigens: OKT9, OKT10, anti-Dr, and Tac antigen. The enzyme content was studied by estimation of the LDH isoenzyme distribution and the enzymes of the purine metabolism ADA and PNP. In addition, the in vitro responsiveness of the T lymphocytes from tonsils and blood to human recombinant interleukin 2, to the lectins PHA, Con A and PWM was also studied. The LDH isoenzyme pattern expressed as B:A ratio decreases progressively after in vitro activation of T lymphocytes. The B:A ratio is already significantly different as early as 12 hr after activation, at a time that OKT9 and Tac are already expressed, but before the expression of OKT10, HLA-Dr, and the onset of the DNA synthesis. Tonsillar T lymphocytes exhibit also a significantly lower B:A ratio, but the activation antigens are not detected on their surface, except for the Tac antigens by means of a sensitive protein A rosette assay. Tonsillar T lymphocytes have a better responsiveness to lectins and recombinant II-2 than the corresponding circulating T lymphocytes. Therefore we are in favor of the hypothesis that tonsillar T lymphocytes contain activated T lymphocytes.

Selective covalent modification of newly synthesized activation-induced sialoglycoconjugates on the T lymphocyte membrane

Resting human lymphocytes were oxidized by periodate and subsequently reduced with borohydride to block the aldehydes formed. The cells were then incubated for 24 or 48 hours with (or without) the mitogenic lectin phytohemagglutinin. A second oxidation with periodate at the indicated times resulted in strong surface-aldehyde formation in samples incubated with the mitogen, compared to control samples which exhibited very low quantities of aldehydes. The data show that this elevation in aldehyde formation was strictly dependent on protein synthesis, similarly to the appearance of Tac antigen in these cells. Cell surface aldehydes were detected in flow cytometry with a fluoresceinated hydrazide molecule and electrophoretically with biocytin hydrazide in conjunction with 125I-streptavidin. The proposed method for the elimination of the chemical reactivity of carbohydrates from the surface of resting lymphocytes thus enabled the selective covalent modification of newly synthesized sialoglycoconjugates formed upon a mitogenic trigger. The data also suggest the existence of a very low turnover rate of sialoglycoconjugates on the resting lymphocyte membrane.

The human T-cell leukemias: clinical, cytomorphologic, immunophenotypic, and genotypic characteristics

The distribution of the conventional lymphoid cell markers on T lymphocytes and the principal panels of monoclonal antibodies used to recognize distinctive T-lymphocyte-associated differentiation antigens are discussed. These reagents have been used to probe the early and late stages of T-cell differentiation, and a hypothetical schema of T-cell differentiation has been constructed. Application of these reagents to the investigation of neoplastic T cells has resulted in the determination of the subset of origin and the stage of differentiation of the neoplastic cells in T-cell-derived lymphoproliferative malignancies. Recent advances in molecular biology have made possible the Southern blot hybridization analysis of DNA extracted from neoplastic T cells for patterns of T-cell-receptor gene rearrangements. Examination of these patterns in benign and malignant T and non-T cell has provided the basis for the use of T-cell-receptor gene rearrangements as specific genetic markers of T-cell lineage, clonality, and differentiation. These and other advances have resulted in the delineation of a new category of T-cell neoplasia, the adult T-cell leukemia/lymphoma syndrome. They have also demonstrated that the majority of clinically indolent neoplasms composed of large granular lymphocytes in so-called T gamma-lymphoproliferative disease are monoclonal proliferations. Further phenotypic, functional, and genotypic analyses of the T-cell malignancies should provide better understanding of T-lymphocyte differentiation and heterogeneity. Such studies should also lead to better clinicopathologic correlations and greater understanding of the basis for the clinical diversity of the T-cell-derived lymphoproliferative malignancies.

T-cell colony formation in patients with T-cell malignancies: growth factor requirements for in-vitro proliferation of peripheral blood T-cell colony-forming cells

Peripheral blood T colony-forming cells (T-CFC) from patients with T-cell malignancies are capable of proliferation in methylcellulose, in the absence of added growth factors or mitogenic stimulation. We show here that based on the spontaneous plating efficiencies of their T-CFC, two groups of patients can be established: Group A (10 patients) with a high colony number (more than 100 colonies/10(5) seeded cells), and group B (12 patients) with less than 100 colonies/10(5) cells. The addition of interleukin 2-(IL2) containing PHA-leukocyte conditioned medium enhanced colony growth from group B but not group A patients. Moreover, both biochemically purified and recombinant IL2 induced the colony growth from group B but not group A patients without any other stimulation. In addition, a monoclonal antibody (moAb) against the IL2 receptor (IL2-R; anti-Tac) inhibited the spontaneous colony formation from T-CFC of both groups of patients. These observations strongly suggest that IL2-R are involved in the spontaneous colony growth of T-CFC. To determine whether IL2 is also involved in the spontaneous colony formation, media conditioned (LCM) by unstimulated leukemic cells were tested for IL2 activity. A constitutive release of IL2 was detected in LCM from only 2 out of 10 patients tested, and some of them were capable to inhibit thymidine incorporation by IL2-dependent cells cultured in the presence of highly purified IL2. However, most of these LCM contained a T-cell colony-promoting activity (TCPA) inducing colony formation from both normal resting and PHA-stimulated E+ clonogenic cells without added IL2 or mitogenic stimulation. TCPA-containing LCM induced the expression of functional IL2-R and IL2 release by normal resting lymphocytes. TCPA was constitutively released by blast-enriched cell fractions suggesting that it is released by the leukemic cells.