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W F Chen

Publications and source records attributed to W F Chen.

At least 19 recordsLinked to original sources
PubMed1992

[Effect of aging on the syndrome of essential debility and evil reality--an exploration on mechanism of senility by traditional Chinese medicine].

Effect of aging on essential debility and evil reality was explored by an epidemiological investigation of clinical syndrome with TCM in 878 cases of middle and old-aged patients, inquiring into their relation of senility with visceral weakness and stagnation of Qi, blood stasis, and phlegm turbid. The results indicated that (1) several viscera, feeble and damaged, were the basis of senility, and the feeble kidney was the stress; (2) the syndrome of stagnation of Qi, blood stasis and phlegm turbid speeded up process of senility. The mechanism of feeble phenomena appeared in the middle-old aged patients is that with the rise of age in the patients observed there was interaction between the feeble visceral function and the syndrome of stagnation of Qi, blood stasis and phlegm turbid, that is, there was interaction between essential debility and evil reality. Essential debility may lead to evil reality and the latter will worsen essential debility. Thus, on repeating themselves in alternate cycles, a systemic hypofunction will be formed up to exhaustion. Therefore, "to nourish essential debility first and to purge evil reality second" should be considered as an essential direction of preparing anti-aging drugs in TCM.

Aged↗
PubMed1991

IL-10: a novel cytotoxic T cell differentiation factor.

A previous report concluded that a new cytokine, designated IL-10, is a growth cofactor for thymocytes, spleen, and lymph node cells. In this report, we have focused on the effects of IL-10 on CD8+ spleen T cells. We first observed that IL-10 enhances the growth of CD8+ T cells to IL-2. We then investigated the effect of murine rIL-10 on the induction of murine effector CTL from CTL precursors (CTL-p) using both bulk and filler cell-free limiting-dilution cultures. IL-10 alone could not induce Con A-activated FACS-sorted CD8+ T cells either to proliferate or to generate effector CTL. In combination with IL-2, however, IL-10 augmented the cytolytic activity of effector CTL generated from Con A-activated spleen CD8+ T cells in bulk cultures incubated for 5 days. In limiting-dilution cultures (using solid-phase anti-CD3 mAb as stimulus), IL-10, in combination with IL-2, substantially increased the CTL-p frequency and augmented the cytolytic activity per clone expanded from one CD8+ T cell when compared with cells cultured in IL-2 alone. Kinetic studies showed that IL-10 is required at both early and late culture stages for optimal generation of effector CTL. The potentiating effects of IL-10 on CTL function were neutralized by an anti-IL-10 mAb. These results indicate that IL-10 has direct effects on mature T cells, and suggest that IL-10 also functions as a cytotoxic T cell differentiation factor, which promotes a higher number of IL-2-activated CTL-p to proliferate and differentiate into effector CTL. In contrast, IL-10 did not enhance significantly the lymphokine-activated killer cell activity of IL-2-grown CD8+ cytotoxic T cells.

Animals↗
PubMed1989

Distinct patterns of lymphokine requirement for the proliferation of various subpopulations of activated thymocytes in a single cell assay.

The frequency and capacity for clonal expansion of several murine thymocyte subpopulations responsive to various IL (fetal day 15, and adult CD4-8-, CD4+8- and CD4-8+) were investigated using a single-cell limiting-dilution cell culture system without filler cells. This assay requires the presence of PMA and ionomycin. The main conclusions of these studies are the following: 1) IL-4 is a better growth factor than IL-2 for immature thymocytes (fetal day 15 or adult CD4-8-). 2) IL-2 is a better growth factor than IL-4 for mature phenotype thymocytes (CD4+8- and CD4-8+). 3) IL-4 is a relatively poor growth factor for adult CD4-CD8- thymocytes and CD4+CD8- thymocytes, while it induced strong responses in fetal day 15 and CD4-8+ thymocytes. 4) IL-6 enhanced the response of CD4+8- thymocytes to either IL-2 or IL-4. 5) Cortisone-resistant thymocytes grown initially with IL-4 and then switched to IL-2 showed a significant decrease in cloning efficiency. No inhibitory effect was observed when cells were cultured first with IL-2 and then switched to IL-4. 6) Finally, supernatant from Con-A stimulated rat spleen cells induced maximal growth of all adult thymocyte populations tested, suggesting that unidentified thymocyte growth factor(s) remain to be characterized. These results indicate that the maturational stage of thymocytes determines their requirements for activation and proliferation.

Animals↗
PubMed1989

IL-2 and IFN-gamma are two necessary lymphokines in the development of cytolytic T cells.

A filler cell-free limiting-dilution microculture system has been developed for the expansion and differentiation of a high proportion of single CD4-CD8+ T cells into cytolytic T cell (CTL) clones. The stimulus used was PMA together with the calcium ionophore ionomycin. The growth and differentiation factors were rIL-2, together with either a Con A-stimulated spleen cell supernatant (CAS) or rIFN-gamma. CTL activity was monitored by an autoradiographic 111In-release assay. With CAS and rIL-2 present, 50% of all potential precursors (CTL-p) produced cytolytic clones. Substitution of rIFN-gamma for CAS gave a similar efficiency with up to 42% of CTL-p producing cytolytic clones. rIL-2 alone allowed only a small proportion (6%) of CD4-CD8+ T cells to become cytolytic clones. Addition of rIL-2 and rIFN-gamma at various stages of the culture demonstrated that IL-2 was required throughout, but exogenous IFN-gamma was required only during the early stages. It is concluded that for at least 40% of all CTL-p, the lymphokines IL-2 and IFN-gamma are essential and act in synergy to induce proliferation and differentiation into CTL.

Animals↗
PubMed1988

Growth of single T cells and single thymocytes in a high cloning efficiency filler-cell free microculture system.

A high cloning-efficiency microculture system is described in which single T cells, stimulated to divide by phorbol ester and calcium ionophore, grow rapidly under the influence of purified growth factors in the absence of other cells. The kinetics of clonal growth has been monitored over a five day period by phase-contrast microscopy. Mature peripheral T cells, and mature subpopulations from the thymus, responded with a cloning efficiency over 80%; they required IL-2 as a minimum but several other factors enhanced growth. Ly2+L3T4- thymocytes (mean doubling time 10.4 hr) grew more rapidly than Ly2-L3T4+ thymocytes (mean doubling time 15.2 hr). Early (Ly2-L3T4-) thymocytes responded with a cloning efficiency of 60%; their efficient growth was dependent on both IL-1 and IL-2. The typical Ly2+L3T4+ cortical thymocyte did not grow under these conditions.

Animals↗
PubMed1987

Susceptibility of mammalian cell cultures to infection with arbo-togaviruses.

Six alphaviruses and four flaviviruses were inoculated intracerebrally into 1 to 3 days old suckling mice. All mice developed CNS diseases and died 2-5 days post-infection. It appeared that alphaviruses were more virulent than flaviviruses since they brought death to the injected mice earlier than the flaviviruses. The susceptibilities of nine different culture cells to those viruses were also investigated using plaque assay. BHK-21 cells produced clearer plaques and were more sensitive than other cells. Plaque reduction tests using antibodies against various viruses revealed no cross-reactions between alphavirus and flavivirus. However, minor cross-reactions were found within groups. The results of this study suggest that BHK-21 cells can be used for the large scale screening of viruses in domestic animal specimens and for detecting serum neutralizing antibodies against arboviruses.

Alphavirus↗
PubMed1986

The capacity of lymphokine production by peripheral blood lymphocytes from aged humans.

The functional capability to produce interleukin 2 (IL2) and interferon gamma (IFN gamma) by peripheral blood lymphocytes (PBL) from elderly humans was evaluated. Thirty-nine samples of PBL derived from donors aged from 56 to 79 yr were cultured with phytohaemagglutinin (PHA) as stimulus at 37 degrees C for 48 hours. The IL2 activity in the supernatants was measured by its ability to sustain the IL2-dependent CTLL growth. Cultures of elder human T cells produced low level of IL2 activity, that is on the average of 9.7 +/- 9.8 mu/ml, equivalent to 28.1% the IL2 activity in parallel cultures of PBL derived from young donors (34.2 +/- 8.3 mu/ml, assessed on the basis of 145 samples). In the elder humans, the IL2 production by PBL decreased progressively as the increase of the age of the donors. In contrast to the impairment of IL2 production, the amount of IFN gamma secretion by elder human T cells was almost at the same level as that by young human T cells. The average IFN gamma activity of 39 samples of elder PBL cultures and 128 samples of young PBL cultures was 2,961 +/- 736 mu/ml and 3133 +/- 950 mu/ml, respectively. There was no significantly positive correlation between the level of IL2 and IFN gamma when comparison was made based on each individual samples. This implies that it may exist an alternative way of IFN gamma production which does not require the induction by IL2, and the relatively high level of IFN gamma may not impose adverse effect on the IL2 production.

Aged↗
PubMed1986

Cytochalasin B changes the cytoskeletal organization in Newcastle disease virus-infected cells.

The microfilament structures of Newcastle disease virus (NDV)-infected BHK-21 cells were studied in the presence (5 micrograms/ml) or absence of cytochalasin B (CB) by means of phase contrast, indirect immunofluorescence and thin-section immunoelectron microscopy. The results indicated that CB treatment not only impaired virus infections titers and antiactin fluorescence strength but also disrupted cytoplasmic membrane and untagged ferritin-conjugated antibody on the surface of NDV specific antigens.

Actins↗
PubMed1985

Monoclonal antibodies to pseudorabies virus produced by mouse hybridomas.

Monoclonal antibodies to pseudorabies viral capsid protein were prepared by fusing Sp2/0-Ag14 myeloma cells with pseudorabies virus (PrV)-primed Balb/c splenocytes. These monoclonal antibodies were specific for PrV. No crossreaction with Herpes Simplex Virus (HSV, type I) or infectious bovine rhinotrachitis virus (IBR) was found. The reaction between these monoclonal antibodies and PrV was demonstrated by immunofluorescent staining technique and enzyme-linked immunoblotting assay. These antibodies could be a useful diagnostic reagent for PrV as well as a good tool for the study of the capsid protein of PrV.

Animals↗
PubMed1984

T-cell development in the absence of a thymus: the number, the phenotype, and the functional capacity of T lymphocytes in nude mice.

A small but definite proportion of T-lymphocyte-like cells have been reported in nu/nu (nude) mouse spleen despite the congenital absence of a thymus in these animals. We have determined the number and the characteristics of such cells using flow cytometry. The level of T-like cells increased with age. In 4-month-old nu/nu CBA spleen, 14% of all cells expressed some Thy 1 antigen. However, only 4% expressed mature T-cell levels, and only the 2% with the highest Thy 1 also showed a normal distribution of Ly 1 and Ly 2 antigens. These T-like cells were slightly larger than normal nondividing T lymphocytes. We have assessed the total functional capacity of T-like cells in nu/nu CBA spleen using a high-cloning-efficiency limit-dilution culture system. Almost all precursor cells capable of forming clones when stimulated with concanavalin A in the presence of irradiated spleen cells and growth factors, and almost all precursors of those clones that were cytolytic in a lectin-mediated tumor-cell-lysis assay, were within this 2% subpopulation of nu/nu spleen cells with mature T-cell markers. Increased levels of purified interleukin 2 failed to induce further precursor function, indicating that maturation of pre-T cells was not obtained. However the nu/nu spleen cells bearing mature T-cell markers displayed only 10-30% of the cloning efficiency of normal splenic T cells. The majority of nu/nu spleen T-like cells, even within this phenotypically "normal" subset, appeared to be nonfunctional. We conclude that the absence of a thymus leads to qualitative, as well as quantitative, deficiencies in the T-cell population, and various interpretations are discussed.

Animals↗
PubMed1984

The functional capabilities of cells leaving the thymus.

There has been a controversy for many years over the functional status of cells that leave the thymus (thymus migrants) to populate the peripheral lymphoid organs. Are they immunoincompetent like cortical thymocytes and so probably derived from them, or are they functionally mature like medullary thymocytes? Until recently the techniques used to assess putative thymus migrants have been indirect, but it is now possible to measure the function of recent thymus migrants directly. We used intrathymic injection of a solution of fluorescein isothiocyanate to label thymocytes, and used electronic cell sorting to purify the fluorescent cells that accumulate in the periphery over the following 3 to 4 hr. The migrants have been enriched from an original frequency of about 1:1000 in lymph nodes and spleen, to greater than 98% purity. These cells have been compared with normal peripheral T cells for proliferative and cytotoxic precursor activity in a high cloning efficiency, lectin-induced, limit dilution culture system and in an allospecific limit dilution system. The frequency of precursors of proliferative lymphocytes and cytotoxic lymphocytes and the size of the clones produced is the same for recent migrants and peripheral T cells. Thus by the criteria of proliferation and cytotoxic responses to mitogens and generation of allospecific CTL, thymus migrants, a few hours after their emigration from the thymus, are fully immunocompetent; we therefore see no evidence of a post-thymic precursor-type cell that requires major maturation steps after leaving the thymus.

Animals↗
PubMed1983

Development of large granular lymphocytes with anomalous, nonspecific cytotoxicity in clones derived from Ly-2+ T cells.

T cells cultured at limit dilution for 8 days in a concanavalin A-stimulated, filler-cell and growth factor-supported system produced cytolytic clones with high efficiency. These clones were not specific, lysing a wide range of targets, syngeneic and allogeneic, of tumor and normal cell origin. Lysis was a cell-mediated phenomenon but was not blocked by anti-Ly-2. One H-2-negative target was lysed, but one was resistant. Xenogeneic (human) tumor cells were not lysed. The cells in the clones were large, vacuolated, granular lymphocytes. They originated from single Ly-2+ responder cells and not from irradiated filler cells. Therefore, activated lymphocyte killers and other natural killer-like cells may be differentiated elements of the Ly-2+ T-cell lineage.

Animals↗