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Biomedical subjects

L Rogozinski

Publications and source records attributed to L Rogozinski.

18 recordsLinked to original sources
PubMed1991

Specific triggering of gamma, delta T cells by K562 activates the gamma, delta T cell receptor and may regulate natural killer-like function.

Freshly isolated and resting gamma/delta T cell lines, although capable of lysing a variety of MHC-unrestricted targets, fail to lyse K562. Yet, the killing of K562 can be specifically induced by antibodies to CD3 or delta-chains. Although this phenomenon may be caused by redirected lysis, it also raised the possibility that K562 may possess ligands capable of specifically interacting with the gamma/delta receptor. We found that K562 specifically induced both CD3 and delta modulation as well as IL-2R expression and IL-2 production by gamma/delta cells, supporting the idea that the TCR-gamma/delta is specifically triggered by K562 cells. Moreover, although the gamma/delta cell clones lysed other target cells (e.g., Molt 4, U937, Jurkat etc.), these latter targets did not induce delta modulation or IL-2R expression. In addition, F(ab)2 anti-CD3 antibodies inhibited activated gamma/delta T cells from killing K562 but did not inhibit the lysis of the other targets. Taken together, these results suggest that gamma/delta cells lyse some targets by utilizing receptors (perhaps NK-like) distinct from the gamma/delta receptor. We also found that triggering of the gamma/delta receptor by K562 inhibited the capacity of resting gamma/delta to lyse Molt 4 cells under conditions in which the K562 cells were not lysed. These findings suggest that the gamma/delta receptor maybe directly involved in the lysis of certain targets (i.e., K562) and, importantly, may potentially regulate the function of NK-like receptors that are involved in the lysis of other targets.

Animals↗
PubMed1989

Evidence that the glucose transporter serves as a water channel in J774 macrophages.

Water transport across plasma membranes is a universal property of cells, but the route of such transport is unclear. In this study, volume changes of cells of the J774 murine macrophage-like cell line were monitored by recording the intensity of light scattered by the cells. We investigated the effects of several inhibitors of glucose transport on cell membrane osmotic water permeability as calculated from the rates of cell volume change. Cytochalasin B (2.5 micrograms/ml), phloretin (20 microM), and tomatine (3 microM) reversibly blocked glucose uptake into these cells. All three inhibitors reversibly decreased the osmotic water permeability of J774 cells from 89.6 +/- 3.2 to 27.2 +/- 1.4 microns/sec. We conclude that a major component of the osmotic water flow across the plasma membranes of these cells is accounted for by water traversing their glucose transporters.

3-O-Methylglucose↗
PubMed1988

Structure of the gamma/delta T cell receptor of a human thymocyte clone.

The CD3+, IL-2-dependent normal human thymocyte clone, CII, expresses on its surface a CD3-associated gamma/delta TCR. We have further elucidated the structure of this receptor from the nucleotide sequence of cDNA and genomic clones from CII that encode functional TCR-gamma and -delta chains. We find that the CII line expresses a C gamma 2 constant region that is a polymorphic form lacking a copy of an internal exon; the sequence of this constant region accounts for the size of the gamma chain and noncovalent linkage of gamma and delta chains in the CII TCR. The V gamma region used for the CII TCR is identical to the several previously characterized expressed human V gamma segments. Possible implications of this finding are discussed.

Base Sequence↗
PubMed1986

Human helper-T-cell function does not require T4 antigen expression.

The relationship between immunoregulatory T-cell function and the expression of T-cell subset-specific differentiation antigens was examined using a phenotypically anomalous human T-cell line (TCL), termed H-1. H-1 cells were found to express T11, extremely high levels of T3, but no T4 nor T8 antigen. Despite their lack of T4 antigen expression, H-1 cells could be activated by coculture with pokeweed mitogen (PWM), anti-T3 antibody, or autologous B cells to provide potent help for B-cell differentiation into plaque-forming cells (PFC). In contrast, H-1 cells did not suppress the PFC response triggered by PWM-activated T4+ cells. These results demonstrate that the expression of the T-cell subclass-specific differentiation antigen, T4, is not required for a T cell to become activated and to implement the program for helper function. In addition, enhanced expression of T3 on the T4-, T8-, H-1 cell surface may reflect a compensatory upregulation of the T3/Ti receptor complex on T cells which are deficient in these nonpolymorphic associative recognition structures.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1984

Construction of human T-cell hybrids with helper function.

Human T-cell hybrids with helper activity were obtained after fusion of phytohemagglutinin-activated normal human T cells with a 6-thioguanine-resistant, aminopterin-sensitive human T-cell line. This mutant line, designated CEM-T15, was derived from the human T-cell line CEM after mutagenesis with ethyl methanesulfonate. The polyethylene glycol induced fusion and the selection in hypoxanthine- aminopeterin -thymidine medium were performed by modification of standard somatic cell hybridization techniques. After fusion, the strategy for selecting hybrids consisted in screening growing cultures for the presence of cells expressing the OKT3 cell surface differentiation antigen. OKT3 was chosen because it is present in 85-95% of normal human T cells but absent from CEM-T15 cells. Thus, OKT3+ cells growing 5-7 weeks after fusion most likely represented hybrids between normal T cells (OKT3+) and continuously growing CEM-T15 cells (OKT3-). Several of the hybrids were tested for their capacity to promote pokeweed mitogen-induced antibody production by B cells. These experiments demonstrated that many of the hybrids had helper activity. Periodical testing of these uncloned hybrids for helper activity revealed functional instability, with most of the hybrids losing helper activity after 20 weeks of continuous culture. However, early and repeated cloning of the same hybrids resulted in a series of hybrid clones with helper activity still present more than 8 months after fusion. In more recent fusions, we have demonstrated that human helper hybrids producing helper factor(s) can also be obtained. These and similar hybrids with different functions will be of considerable importance in further studies of the immunobiology of human T lymphocytes.

Antigens, Surface↗
PubMed1984

Functional analysis of human T cell subsets defined by monoclonal antibodies. VI. Distinct and opposing immunoregulatory functions within the OKT8+ population.

In the present study, we investigated the immunoregulatory potential of OKT8+ cells after in vitro activation. Initial studies had demonstrated that the T cell marker OKT4 identifies T cell sets containing helper cells, whereas OKT8 reacts with the suppressor and cytotoxic T cell effectors. More detailed analysis of the OKT4+ subset, however, demonstrated that there is functional heterogeneity in the OKT4+ population. The evidence for this heterogeneity arose from studies on (1) the relative radiosensitivities of the distinct immunoregulatory functions of cells contained within this set, and, (2) the effects of the state of activation of this population on immune function. For example, OKT4+ cells included radiosensitive helper cells, radioresistant helper cells, and radiosensitive inducers of suppressor cells. Furthermore, after activation, the OKT4+ population also contained cells capable of suppressing B cell differentiation. Since activation of the OKT4+ population results in the emergence of cells with counterbalancing immunoregulatory properties, it was of interest to determine whether the state of activation of the OKT8+ population influences the immunoregulatory potential of this subset. In the experiments reported here E+ cells were cultured with pokeweed mitogen (PWM) for 60-70 h and then thoroughly depleted of OKT4+ cells, leaving OKT8+ cells. The ability of the PWM-activated OKT8+ cells (first culture) to exert suppressive activity was determined by adding graded numbers of these cells to fresh autologous OKT4+ cells and B cells. The cell mixtures were cultured in the presence of PWM for 5 days and then assayed for plaque-forming-cell (PFC) activity by the reverse hemolytic plaque assay. Our studies demonstrate that activation of OKT8+ cells results in the emergence of cells with apparently counterbalancing immunoregulatory properties. Activated nonirradiated OKT8+ cells consistently suppressed B cell immunoglobulin production. However, the immunoregulatory function mediated by irradiated activated OKT8+ cells is highly dependent on the magnitude of the helper activity obtained with fresh OKT4+ cells. Thus, irradiated activated OKT8+ cells suppressed the generation of PFC only when the level of helper activity was optimal. However, when the level of help was not optimal, no suppressor activity was observed; rather, under these conditions, irradiated activated OKT8+ cells amplify the PFC response. We would emphasize that the amplification function of irradiated OKT8+ cells depends strictly on the presence of fresh OKT4+ cells. Irradiated activated OKT8+ cells alone are not helper cells, since addition of these cells to B cells thoroughly dep

Antibodies, Monoclonal↗
PubMed1984

The T4 surface antigen is involved in the induction of helper function.

The OKT4 monoclonal antibody reacts with a 62K m.w. glycoprotein present on a subset of human T cells with the capacity to help or induce B cell differentiation. The present studies were undertaken to determine whether the T4 molecule itself plays any role in the helper function mediated by T4+ cells. Using a series of monoclonal antibodies (OKT4, OKT4A-E), which react with distinct noncompeting epitopes of the T4 molecule, we found that OKT4A and OKT4E, but not OKT4, antibodies inhibited the induction of B cell differentiation by T4+ cells. This inhibition was apparent when using nonirradiated or irradiated T4+ cells, and was noted over a wide range of concentrations. Importantly, inhibition occurred only if the antibody was present during the first 24 hr of cell culture, and the presence of antibody did not alter the kinetics of induction of B cell differentiation. Thus, these data suggest that the T4 molecule plays an early, critical role in cellular interactions required for helper cell function.

Antibodies, Monoclonal↗
PubMed1983

Relationship between human T cell functional heterogeneity and human T cell surface molecules.

Our knowledge of human T cell differentiation and function has expotentially increased during recent years. With this growth in knowledge there has been an increase in our appreciation of the complexity of the T-T interactions which initiate and control immune responses. A great deal remains to be learned concerning the mechanisms of these complex cellular interactions. In particular, it will be important to precisely understand the clear heterogeneity of functions within isolated subsets of OKT4+ and OKT8+ T cells. Perhaps, as importantly, it will be necessary to define more clearly the functions of the T4 and T8 molecules as well as the precise function of the other defined glycoproteins on the T cell surface. The evidence is clearly emerging that many of those molecules are not solely markers of unique functional subsets and are intimately involved in the functions of T cells.

Animals↗
PubMed1983

Biological functions of T-cell surface glycoproteins.

The OKT4 monoclonal antibody reacts with a 62 KD cell surface glycoprotein present on a subset of human T cells with the capacity to help or induce B-cell differentiation. The OKT8 monoclonal antibody reacts with a 76 KD cell surface glycoprotein present on a subset of human T cells with the capacity to suppress B-cell differentiation. The current studies were undertaken to determine whether the T4 and/or T8 antigens themselves play any role in the helper or suppressor function mediated by OKT4+ or OKT8+ cells. Specifically, we asked if monoclonal antibodies that react with noncompeting epitopes on the T4 or T8 molecules could block helper or suppressor function. Isolated human B cells were triggered in vitro to differentiate into antibody-forming cells (AFC) by autologous OKT4+ cells and macrophages in the presence or absence of OKT4 antibodies. By means of a reverse hemolytic plaque assay, AFC were detected as plaque-forming cells (PFC). We found that OKT4A, but not OKT4, antibody inhibited the PFC response over a wide range of concentrations. The antibodies OKT4B, OKT4C, OKT4D, OKT4E inhibited the PFC response to varying degrees. Importantly, inhibition by OKT4A occurred only if the antibody was present during the first 24 hours of cell culture. In the second set of experiments, OKT8+ cells were added to cultures containing B cells, and OKT4+ cells in the presence or absence of OKT8 antibodies, PFC activity was measured 7 days later. We found that the addition of OKT8E or OKT8G, but not OKT8B, OKT8C, OKT8D, OKT8F, or OKT8H, antibodies significantly inhibits the suppressor function mediated by OKT8+ cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1982

Further dissection of the functional heterogeneity within the OKT4+ and OKT8+ human T cell subsets.

Previous studies have suggested functional heterogeneity within the OKT4+ and the OKT8+ populations. For example, after activation the OKT4+ population contains not only helper cells but also cells capable of suppressing B cell differentiation. Previous studies also indicate that the reciprocal T cell population, OKT8+, does not provide helper activity but contains cytotoxic effector cells and radiosensitive cells important in the suppression of B cell differentiation. Using a new differentiation antigen, OKT17, which recognizes a surface antigen present on the majority of resting normal peripheral T lymphocytes but is present only on a subset of OKT4+ cells after activation, evidence was obtained that two functionally mature subsets can be distinguished within the OKT4+ population itself: OKT4+17+ radiosensitive suppressor cells and OKT4+17- radiosensitive helper cells. Recently, another monoclonal antibody, OKT20, has been described which is present on a small percentage of resting lymphocytes but is expressed in varying proportions on activated T cells. Functional analysis of normal resting human T lymphocytes demonstrated that the OKT20-depleted T cell subset was able to generate cytotoxic cells and to suppress antibody production to the same extent as did OKT8+ cells. On the other hand, when unselected T lymphocytes were cultured for six days in a mixed lymphocyte reaction and then depleted of OKT20 reactive cells, the cytotoxic effector T cells were eliminated. In contrast, OKT20-depleted T cells after identical activation were still able to suppress antibody production. These data provide evidence that following activation of OKT8+ cells, the OKT20 differentiation antigen becomes selectively expressed on cytotoxic effectors but not on suppressor cells.

Antibodies, Monoclonal↗
PubMed1982

Functional analysis of human T cell subsets defined by monoclonal antibodies. V. Suppressor cells within the activated OKT4+ population belong to a distinct subset.

In the present report, we characterize a monoclonal antibody directed at a surface differentiation antigen on human T cells. The monoclonal antibody, OKT17, recognizes a cell surface antigen present on the majority of resting normal peripheral T cells. In contrast, OKT17 is unreactive with normal B cells, B cell lines, T cell lines, or SIg+ CLL. Interestingly, after activation, the antigen recognized by OKT17 is lost from a subset of OKT4+ cells. We took advantage of this finding to explore further the functional heterogeneity within activated OKT4+ cells. Evidence was obtained that the PWM-activated OKT4+ subset remaining after depletion of OKT17-reactive T cells (OKT4+ 17-) contains radiosensitive helperr cells but is devoid of suppressor cells. In contrast, the activated OKT4+ 17+ population contains potent radiosensitive suppressor cells as well as radioresistant helpe cells. Taken together, these studies suggest that the OKT17 monoclonal antibody can differentiate two functionally mature, activated OKT4+ human T cells: OKT4+ OKT17+ radiosensitive suppressor cells and OKT4+ 17- radiosensitive helper cells.

Antibodies, Monoclonal↗
PubMed1981

Generation of functional human T cell hybrids.

Human T cell hybrids were generated by fusing lectin-activated normal and leukemic human T cells with an aminopterin-sensitive human T cell line. This mutant cell line, designated CEM-T15, was derived from the human T cell line CEM after chemical mutagenesis with ethane methylsulfonate and subsequent culture in medium containing 6-thioguanine. After polyethylene glycol-induced fusion, the cells were cultured in hypoxanthine-aminopterin-thymidine selective medium. More than 5 wk after fusion, evidence for successful hybridization was obtained by three independent criteria: (a) The majority of the cultures contained cells expressing the OKT3 surface antigen: this antigen is expressed on normal T cells but not on CEM-T15 cells. (b) Most of the cultures contained polyploid cells. (c) Some of the cultures provided helper activity in the generation of antibody-forming cells. This functional activity is absent from the CEM-T15 parental cell line. Evidence for functional stability of the hybrids greater than 20 wk after fusion was provided by several clones that not only continue growing exponentially but also maintain expression of OKT3 surface antigen and high levels of helper function. These T cell hybrids constructed using antigen-specific human T cells should be of considerable importance in further studies of the immunobiology of human T cells.

Aminopterin↗
PubMed1981

Functional analysis of human T cell subsets defined by monoclonal antibodies. IV. Induction of suppressor cells within the OKT4+ population.

In this report, we explored the functional heterogeneity within the OKT4+ subset of human T cells. Evidence was obtained that although in vitro pokeweed mitogen-activated OKT4+ cells can function as radioresistant helper cells, these activated OKT4+ cells could also exert potent feedback suppression. Despite the induction of suppressor cells after pokeweed mitogen activation, the OKT4+ population maintains its original OKT3+, OKT4+, nd OKT8- surface phenotype. The suppressor cells contained within the activated OKT4+ population were found to be radiosensitive. Importantly, the suppression mediated by activated OKT4+ cells required the presence of radiosensitive cells contained within the resting OKT4+ population. Taken together, these results suggest that the OKT4+ subset of human T cells contains cells that can be activated to differentiate into suppressor cells independent of OKT8+ cells.

Antibodies↗
PubMed1981

Functional analysis of human T cell subsets defined by monoclonal antibodies. III. Regulation of helper factor production by T cell subsets.

In the present report we extended our previous studies demonstrating that obligatory T-T interactions are important in regulating human immune responses in vitro. Functionally distinct human T cell subsets were isolated by complement-mediated lysis using the monoclonal antibodies OKT4 and OKT8. Evidence was obtained that during allogeneic interactions, OKT4+, but not OKT8+, responder T cells are required to generate helper factor(s) capable of polyclonally activating human B cells independent of additional T cell help. Importantly, the alloantigen-induced helper factor(s) production and/or release was found to be suppressed by addition of graded numbers of radiosensitive OKT8+ cells. On the other hand, no evidence was obtained that supernatant derived from alloactivated OKT8+ cells could counterbalance the helper activity generated in the presence of supernatant from alloactivated OKT4+ cells. Furthermore, OKT8+ cells, known to suppress PWM-driven B cell differentiation in the presence of OKT4+ cells, do not suppress B cell differentiation induced by preformed helper factor even in the presence of OKT4+ cells. These data further underscore the importance of functional T-T interactions in immunoregulation in vitro and support the idea that the target of suppression of B cell differentiation, induced either by alloantigen-triggered helper factor or PWM, are OKT4+ cells and not B cells themselves.

Antibodies↗
PubMedDate not supplied

Monoclonal antibodies to E92, an endothelial cell surface antigen.

Two hybridoma-derived monoclonal antibodies have been developed that react with an antigen of molecular weight 92,000 daltons on the surface of human endothelial cells. Cultured human umbilical vein endothelial cells were used for immunization, but the antigen is present on arterial, venous and capillary endothelium, as determined by biotin-avidin immunoperoxidase staining of tissue sections. With this technique, other cell types in the tissues which were examined were not reactive, except for scattered fibroblasts and histiomonocytic cells, trophoblastic cells of the placenta, and benign immature mesenchymal cells in a renal cystadenocarcinoma. By cytofluorography, the antibodies were found to be unreactive with granulocytes, T lymphocytes, B lymphocytes, and the majority of monocytes. Fibroblasts were reactive with the antibodies, but the fluorescence tracings indicated a lower density of antigen on these cells than on endothelial cells. Immunoreactivity of fibroblasts could be decreased by treatment of the cells with thrombin, trypsin, or neuraminidase, whereas these enzymes did not affect the immunoreactivity of endothelial cells. The reactive antigen (E92) does not appear to be any of several previously described endothelial cell proteins, because of its molecular weight and its absence on other cell types. The presence of E92 on trophoblastic cells of the placenta and immature mesenchymal cells, as well as fibroblasts and endothelial cells, may indicate that it is a primitive antigen of mesodermal tissue that is lost by most cell types during differentiation.

Adenocarcinoma↗