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Biomedical subjects

S M Fu

Publications and source records attributed to S M Fu.

At least 73 records · Page 4Linked to original sources
PubMed1988

Production of tumor necrosis factor/cachectin by human B cell lines and tonsillar B cells.

The production of TNF/cachectin by human B cell lines and tonsillar B cells was examined. Of the 15 B cell lines examined, 9 cell lines synthesize TNF mRNA constitutively. PMA stimulated most cell lines to accumulate increased amounts of TNF. SeD, 8866P, 32al, RPMI 1788, and four bone marrow-derived EBV-transformed cell lines accumulated high levels of TNF mRNA when stimulated by PMA. TNF production by these cell lines was examined. RPMI 1788 and WIH8 produced little TNF constitutively, but synthesized 5-7 ng/ml TNF when stimulated by PMA. A pre-B cell line, Nalm-6, did not synthesize any detectable amount of TNF mRNA, even with PMA stimulation. Tonsillar B cells could also be stimulated to produce TNF. PMA or Staphylococcus aureus Cowan I strain (SAC) alone stimulated some TNF mRNA accumulation, whereas B cell growth factor (BCGF) or anti-mu did not. This accumulation was synergistically elevated by the combinations of PMA and SAC, or PMA and anti-mu. BCGF increased PMA-, SAC-, PMA plus SAC-, or PMA plus anti-mu-induced TNF mRNA accumulations about twofold. The accumulation of TNF mRNA in tonsillar B cells stimulated by PMA plus SAC was between 32 and 48 h, the same peak interval as the accumulation of TNF and IL-2 mRNA in tonsillar T cells. This is in contrast to PMA or PMA plus A23187-stimulated RPMI 1788 cells in which TNF mRNA accumulation was maximal at 1-2 h. TNF activities found in tonsillar B cell supernatants correlated with the TNF mRNA levels in the cells. However, more TNF activity was found on the second-day than the third-day supernatants, indicating active TNF uptake by the B cells. Cyclosporin A (CsA) inhibited SAC and anti-mu responses in B cells in much the same way as the anti-CD3 responses in T cells. SAC-, PMA plus SAC-, and PMA plus anti-mu-stimulated, but not PMA-stimulated, increases in TNF mRNA accumulations in tonsillar B cells were inhibited by CsA. TNF production seems to increase in parallel with B cell proliferation, but the relationship of these two functions needs to be further examined.

B-Lymphocytes↗
PubMed1988

Production of tumor necrosis factor/cachectin by human T cell lines and peripheral blood T lymphocytes stimulated by phorbol myristate acetate and anti-CD3 antibody.

The induction of mRNA synthesis and accumulation of TNF/cachectin and lymphotoxin (LT) mRNAs in T leukemic cell lines and freshly isolated T cells were studied by Northern blot analyses. Without stimulation, TNF mRNA was barely detected in four T cell lines (CEM, KE4, MT-1, and SKW-3) and not detectable in Molt-4 and Jurkat cells, while a considerable amount of TNF mRNA was observed in HSB-2 cells. When stimulated by PMA, these T cell lines accumulated varying levels of TNF mRNA. All seven T cell lines expressed LT mRNA when unstimulated and responded well to PMA by increased accumulation of LT mRNA. The calcium ionophore A23187 by itself had no effect on TNF and LT mRNA accumulations in these cell lines. The CD3+ T cell lines did not respond to anti-CD3 mAb T3-II alone. However, A23187 and mAb T3-II further elevated TNF and LT mRNA accumulations in PMA-treated T cell lines. Synergism between PMA and mAb T3-II was modest in the CD3+ cell lines. A slight difference in kinetics of TNF and LT mRNA accumulations was noted. In addition, heterogeneities in TNF and LT expressions by these cell lines in responses to PMA and other stimuli were observed. In monocyte-depleted peripheral blood T cell populations. PMA was able to induce both TNF and LT mRNA syntheses. This effect was potentiated markedly by the addition of anti-CD3 mAb T3-II. This synergistic response to anti-CD3 mAb and PMA provided further evidence that T cells were the source of TNF synthesis in these cultures. There was a difference in the kinetics of TNF mRNA accumulation and that of LT mRNA. Maximal accumulation of TNF mRNA occurred at 4 h while 8-18 h was required for maximal LT mRNA accumulation. IL-2 mRNA accumulated at an intermediate peak time of 4-8 h. Western blot analyses and cytotoxicity assays with L cells as targets indicated that these T cell lines and peripheral blood T cells secreted TNF. These results provide further evidence that human T cells are capable of making TNF as well as LT under appropriate stimulations. Their productions are an integral part of T cell response to activation signals. In addition, it appears that the production of these two closely related molecules is independently regulated.

Antibodies, Monoclonal↗
PubMed1988

Expression of a 33-kDa antigen Tm 1 on lymphocyte surface after modulation of cell surface antigens by IgM monoclonal antibody.

The mAb Tm 1 was obtained from a fusion of SP2/O tumor cells with spleen cells from CF1 mouse immunized with T cells modulated by an IgM anti-CD3 mAb.mAb Tm 1 reacted with IgM anti-CD3 modulated T cells (66.6%) but not with unmodulated T cells (4.4%). Tm 1 was not expressed on T cells modulated with either IgG2a or IgG1 anti-CD3 mAb. Immunoprecipitation from 125I-labeled CD3-modulated T cells showed that Tm 1 Ag is a single polypeptide of 33 kDa under reducing and nonreducing conditions. Kinetic studies revealed that Tm 1 was detectable on T cells 10 min after incubation and maximally expressed after 4 h of incubation with IgM anti-CD3 mAb. CD3 expression was markedly modulated by this anti-CD3 mAb after the same period of incubation. Studies with cycloheximide revealed that Tm 1 expression on T cells does not require new protein synthesis. Tm 1 expression persisted long after CD3-reexpression 24 h later. Tm 1 was present on a small fraction of circulating T cells, B cells, and monocytes and absent from granulocytes, platelets, E, and thymocytes. Tm 1 was not expressed on T cells after various activation stimuli but was expressed on B cells upon activation. Additional studies indicate that IgM mAb against other T cell differentiation Ag and IgM mAb against B cell Ag also lead to the expression of Tm 1 on these cells. Thus, modulation of surface Ag by IgM mAb externalizes this cytoplasmic Ag. However, one exception has been noted. Purified mAb Tm 1 was not mitogenic and was unable to block either the T cell proliferation induced by 12-O-tetradecanoyl phorbol-13-acetate plus anti-CD3 mAb and other T cell stimuli, or the B cell proliferation induced by B cell mitogens. The role of Tm 1 on lymphocyte function remains to be determined.

Animals↗
PubMed1988

Effect of tumor promoter 12-O-tetradecanoyl-phorbol 13-acetate on CD 7 expression by T lineage cells.

Phorbol esters exert diverse effects on cellular activation and differentiation. CD 7, a differentiation antigen appearing early in T cell ontogeny, may be involved in the activation and differentiation processes. CD 7 was found to be rapidly down-regulated by 12-O-tetradecanoylphorbol 13-acetate (TPA) from mature T cell surface. The time course of CD 7 down-regulation was similar to that of other functionally important T cell antigens, CD 3 and CD 4. Within 2 h, TPA at 10 to 30 ng/ml induced a complete down-regulation of CD 7. Twenty-four hours later, the reappearance of CD 7 on TPA-treated cells was observed. This phenomenon was monocyte independent. In contrast, CD 7 expression on thymocytes was resistant to the effect of TPA. In addition, certain leukemic T cells were also resistant to TPA-induced CD 7 down-regulation. The mechanism underlying TPA-induced CD 7 down-regulation was investigated further. Synthetic diacylglycerol, sn-1,2-dioctanoylglycerol, which activates protein kinase C, did not induce down-regulation of CD 7 on mature T cells. Ionomycin, a calcium ionophore, did not down-regulate this antigen either. Thus, it is concluded that the processes of protein kinase C activation and/or cytosolic calcium influx are not sufficient for TPA-induced CD 7 down-regulation; other pathways induced by TPA may be responsible.

Antibodies, Monoclonal↗
PubMed1988

Dissociation of TPA-induced down-regulation of T cell antigens from protein kinase C activation.

The tumor promotor 12-O-tetradecanoylphorbol-13-acetate (TPA) has diverse effects on lymphoid cell function. Two of the early effects were the induction of early activation antigen EA1 and the down-regulation of certain T cell differentiation antigens (CD3, CD4, CD7). The mechanisms of these TPA effects were investigated. It was confirmed that EA1 expression was dependent on protein kinase C (PKC) activation. Synthetic diacylglycerols were capable of inducing EA1 expression. In addition, inhibition of PKC by the kinase inhibitor, H7, led to the inhibition of EA1 expression induced by TPA and synthetic diacylglycerols. In contrast, down-regulation of T cell differentiation antigens by TPA was not dependent on PKC activation. Synthetic diacylglycerols did not induce down-regulation of T cell antigens and H7 had no effect on the down-regulation of T cell antigens induced by TPA. These data would suggest that TPA exerted its effects on T cell function by mechanisms in addition to the activation of PKC alone. One possible mechanism would be the activation of the calmodulin-dependent pathway(s) since its inhibition resulted in the reversal of TPA-induced down-regulation of the T cell differentiation antigens.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1988

Human antibodies to neurofibrillary tangles and astrocytes in Alzheimer's disease.

Multiple B cell lines established by Epstein-Barr viral transformation from six patients with Alzheimer's disease (AD) and six age-matched controls were screened immunocytochemically for their reactivities with AD and normal brains as well as to cell lines such as HeLa, fibroblasts and neuroblastoma. A higher incidence of reactivity with neurofibrillary tangles in situ was found among the cell lines from AD patients (23/866) in comparison with those from normals (6/803). Three cell lines from a patient with a definitive neuropathological diagnosis of AD were shown to secrete antibodies preferentially reactive with astrocytes in the grey matter of AD brain and one cell line from a normal elderly individual was shown to specifically react with neurofibrillary tangles and plaque neurites. These four antibodies were not reactive with normal brains or cell lines. These unique human antibodies may be useful in the diagnosis of AD and offer clues to its pathogenesis.

Alzheimer Disease↗
PubMed1987

Functional competency of T cell antigen receptors in human thymus.

The T cell antigen receptor is likely to play a role in both positive and negative selection in the thymus. Three populations of thymocytes can be distinguished by the level of expression of the CD3-alpha/beta-chain heterodimer of the T cell antigen receptor (CD3/Ti alpha/beta) complex. Cells which fail to express these receptors or express low levels of receptors are contained in a population of thymocytes which express low levels of the CD5 antigen and are predominantly CD4+/CD8+. Thus, these cells appear to be relatively immature phenotypically. In contrast, the cells which express high levels of CD3/Ti alpha/beta co-express high levels of CD5 and are predominantly contained in the more mature single positive cells which express either CD4 or CD8. With the calcium-sensitive dye, Indo-1, and immunofluorescence, we demonstrated that, despite the relative phenotypic immaturity of cells which express low levels of CD3/Ti alpha/beta, these antigen receptors are able to mediate transmembrane signaling when stimulated with CD3 monoclonal antibodies. Although increases in calcium were observed in these CD3/Ti alpha/beta-low expressing cells in response to anti-CD3, no proliferative response was observed, even in the presence of phorbol myristate acetate. Proliferative responses were observed in the more mature cells which express high levels of CD3/Ti alpha/beta. These results suggest that, rather than a defect in the functional capability of the antigen receptor complex to mediate transmembrane signaling events, cellular responses to signals generated by the antigen receptor may differ at various stages of thymocyte development.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

Autoantibodies to neurofibrillary tangles and brain tissue in Alzheimer's disease. Establishment of Epstein-Barr virus-transformed antibody-producing cell lines.

Multiple EBV-transformed B cell lines were established from five patients with a clinical diagnosis of Alzheimer's disease (AD) and six age-matched controls. The supernatants were screened for antibody activity against SDS-treated isolated neurofibrillary tangles (NFT). Reactive supernatants were identified from both the AD and control group. The frequencies of anti-NFT antibody-secreting lines were 6.3 and 1.6% for the AD and the control groups, respectively. A proportion of these supernatants also stained NFT in situ and neurons and/or glia in sections of the frontal and the temporal cortexes of autopsied AD and normal brains, as well as cells from three cell lines (HeLa, fibroblast, and neuroblastoma). Several patterns of staining were revealed by these supernatants, indicating different reactive antigens. One supernatant stained NFT and astrocytes in sections from AD brains. It did not stain sections from two normal brains. This cell line is the result of the immortalization of a circulating B cell making antibody specific for an antigen in AD. The present approach may provide new insights in the pathogenesis of AD.

Alzheimer Disease↗
PubMed1987

Marked increase in the frequency of psoriatic arthritis in psoriasis patients with HLA-DR+ keratinocytes.

Immunocytochemical studies with a monoclonal anti-HLA-DR antibody were performed on skin sections and keratinocyte (KTC) suspensions obtained from suction blisters of active psoriatic plaques. HLA-DR+ KTCs were found in the plaques of 23 of 38 patients with active psoriasis. Of these 23, 16 had clinical findings typical of psoriatic arthritis (PA); none of the 15 patients who lacked HLA-DR+ KTCs had PA. Although KTC HLA-DR expression was more prevalent in patients with severe skin disease, 7 of the 23 patients with HLA-DR+ KTCs in active psoriatic plaques had mild skin disease; 4 of these 7 had PA. Nail pitting or duration of skin disease did not account for increased incidence of PA in patients with HLA-DR+ KTCs. All psoriasis patients with arthritis received nonsteroidal antiinflammatory drug therapy; 14 received additional therapy directed primarily to the cutaneous manifestations of psoriasis. Nine of these noted arthritis improvement with concurrent skin response; however, in 5 patients, arthritis activity increased, despite improvement of the cutaneous disease. Two other patients, treated with methotrexate, also had concurrent skin and joint improvement. These data suggest that psoriasis patients with HLA-DR+ KTCs are at increased risk for the development of associated arthritis.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1987

Productive infection of cultured human lymphoid cells by adenovirus.

We investigated infection of cultures from established human B- and T-cell lines by adenoviruses. Infection by adenovirus type 2 or 5 was productive by the criteria of viral DNA replication, RNA synthesis, immunofluorescent staining of viral proteins, and assembly of biologically active virions. Whereas the kinetics of infection were reproducible and characteristic for each cell line, there appeared to be no correlation between the kinetics of infection and the origin from which the cell lines were established. In a myeloma and a T-cell line, the kinetics of infection approached those in HeLa cells. The presence of the Epstein-Barr virus genome in B lymphoid cells was not a prerequisite for adenoviral infection. Furthermore, expression of the E1A gene was repressed in myeloma cells in comparison with HeLa cells.

Adenoviruses, Human↗
PubMed1987

Effects of timing acupuncture on nuclear volume of neurosecretory cells in rat supraoptic nucleus.

To see whether the effects of acupuncture on the nuclear volume of neurosecretory cells in the rat supraoptic nucleus (SON) are circadian stage-dependent, 48 male Wistar rats were divided into eight equal groups and standardized in LD12:12 at 21.5 degrees C with food and water ad libitum. At each of four time points [0, 6, 12, and 18 hours after lights on (HALO)], one group (A) was treated by electric acupuncture at a place equivalent to the human "Yongquan" point; another group (C) was left untreated as a control without acupuncture. The nuclear volumes of neurosecretory cells were calculated after the nuclei were measured with a micrometer under a microscope. Circadian variation in nuclear volume was observed for both A and C groups and showed macroscopically two peaks, one at 18 HALO and another at 6 HALO, and a nadir at the time of lights on (0 HALO). The effects of acupuncture appear to differ at various time points. A circadian change in the ratio of the data from the A and C groups at each time point was observed only in the left SON and peaked at 0 HALO. An asymmetry between the left and right SONs characterized their changes and responses to acupuncture. An analysis of variance established a time effect (P less than 0.001) and an interaction between laterality and treatment (P less than 0.037). The results documenting a circadian change of nuclear volume of the SON neurosecretory cells and a laterality-dependent response to acupuncture point to cephalic mechanisms of "Ziwu Liuzhu" chronotherapy by acupuncture and moxibustion.

Acupuncture Therapy↗
PubMed1986

Human T cell activation. III. Rapid induction of a phosphorylated 28 kD/32 kD disulfide-linked early activation antigen (EA 1) by 12-o-tetradecanoyl phorbol-13-acetate, mitogens, and antigens.

With human T cells activated by 12-o-tetradecanoyl phorbol-13-acetate (TPA) as immunogen, an IgG2a mAb, early activation antigen 1 (EA 1), was generated against a 60-kD protein with disulfide-linked 28-kD and 32-kD subunits. Both subunits were phosphorylated. The antigen, EA 1, was readily detected on approximately 60% of isolated and cryopreserved thymocytes, as determined by indirect immunofluorescence. A low level of EA 1 expression was detectable on 6-7% of blood lymphocytes. TPA-activated T cells expressed EA 1 as early as 30 min after activation. By 1 h, 85-90% of the T cells stained with mAb EA 1. By 3-4 h, the expression of EA 1 was detected in greater than 95% of the T cells. Although the percentages of EA 1+ T cells did not change, the intensity of staining increased slightly. After 18-24 h, both the percentage of EA 1+ cells and the intensity of staining decreased gradually. TPA-induced EA 1 expression was independent of monocytes. EA 1 expression was slightly delayed in T cells that were isolated without the rosette selection and treated with TPA. Nevertheless, greater than 85% of these T cells expressed EA 1 within 1 h, and the maximal number of EA 1+ T cells was also detected at 3-4 h. In T cell populations with 1-2% monocytes, about 50-90% of the PHA- or Con A-activated T cells expressed EA 1 with a slower kinetics. EA 1 expression preceded that of IL-2-R in these activation processes. Similarly, T cells activated by soluble antigens (tetanus toxoid and PPD) and alloantigens in MLR also expressed EA 1 after a longer incubation. Approximately 20% of the T cells stained for EA 1 at day 6. EA 1 expression was not limited to activated T cells. B cells activated by TPA or anti-IgM antibody plus B cell growth factor expressed EA 1. The kinetics of EA 1 expression was markedly slower and the staining was less intense. Repeated attempts to detect EA 1 on resting and TPA-activated monocytes and granulocytes have not been successful. However, the detection of EA 1 in nonlymphoid cell lines would indicate that EA 1 may have a broader cell distribution. EA 1 expression was due to de novo synthesis, as the induction of EA 1 was blocked by cycloheximide and actinomycin D.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Expression of HLA-DR molecules by keratinocytes, and presence of Langerhans cells in the dermal infiltrate of active psoriatic plaques.

Immunoperoxidase staining of skin sections and immunofluorescence analysis of keratinocyte suspensions obtained from suction blisters of psoriatic plaques were performed using an mAb, Josh 524.4.1, and Fab'2 fragments of a rabbit antiserum, both of which are directed against nonpolymorphic determinants of HLA-DR molecules. HLA-DR+ keratinocytes were present in plaques, but not normal-appearing skin, from a significant portion of patients with active psoriasis. Double-labelling immunofluorescence experiments with either the monoclonal or polyclonal anti-HLA-DR antibody, in conjunction with the mAb OKT6, which identifies DR+ Langerhans cells, demonstrated that HLA-DR molecules were present on OKT6- keratinocytes. The dermal infiltrate of psoriatic plaques contained T cells expressing the activation antigens, IL-2 receptor (Tac) and HLA-DR, as well as macrophages and OKT6+ cells. There was little difference in the characteristics of the dermal infiltrate between the lesions with or without HLA-DR+ keratinocytes. OKT6+ presumptive Langerhans cells were also found in the dermal infiltrates of patients with lichen planus, contact dermatitis, spongiotic dermatitis, erythema multiforme, basal and squamous cell carcinoma. Studies of keratinocyte suspensions showed that 7-84% of keratinocytes were HLA-DR+. Flow cytometry experiments showed that keratinocytes at all stages of differentiation were HLA-DR+. However, the stem cell-enriched population contained the highest proportion of HLA-DR+ cells. HLA-DR expression by keratinocytes correlated with disease activity. The expression was reversible with successful medical therapy. HLA-DR+ keratinocytes may activate T cells directly or may present an as yet unknown antigen to T cells. These studies provide further support for the hypothesis that immunological mechanisms play an important role in the pathogenesis of psoriasis.

Dermatitis↗