Human immune cells as space travelers.

Experiments in space have shown that T lymphocyte function is altered in more than 50% of space crew members. There is strong evidence that such effect is due to stress rather than to weightlessness per se. However the health of astronauts was never threatened so far. Experiments in-vitro with cultures of human peripheral blood lymphocytes (not from astronauts) have shown that T cell function is dramatically reduced. Recent work with the random positioning machine, a new instrument to simulate conditions similar to microgravity, indicate that there are direct gravitational effects on the genetic expression of interleukin-2 and of its receptor in T lymphocytes.

The fast rotating clinostat: a history of its use in gravitational biology and a comparison of ground-based and flight experiment results.

The fast rotating clinostat has been used in gravitational biology since 1965 to investigate effects of simulated microgravity. Using a microscope, the behavior of cells and organelles within the cells under microgravity conditions can be directly observed during rotation. Experiments with several mammalian cells and unicellular organisms have shown that different cellular functions are affected in simulated microgravity. Almost no changes were noted in the area of developmental biology. A comparison of results from the fast rotating clinostat and flight experiments reveals that the clinostat is a valuable tool to evaluate an organism's sensitivity to gravity changes. Therefore, a biological object proposed for a flight experiment should first be investigated in the clinostat before it is selected. This is especially true in the use of single cells and unicellular organisms.

Effect of head-down tilt bedrest (10 days) on lymphocyte reactivity.

Immunological responses of six healthy males to 10 days of head-down tilt bedrest (HDT) were assessed. Lymphocyte responsiveness was severely reduced immediately before, during, and immediately after the HDT, even though the lymphocyte numbers did not change. By contrast, delayed-type hypersensitivity was not affected. No dramatic changes were found in WBC counts and lymphocyte subpopulations, with the only exception of natural killer (NK) cells which transiently decreased immediately after HDT. Plasma cortisol levels were elevated above normal immediately before and during the HDT. The data suggest that the mitogenic response of lymphocytes was affected by psychological and fluid shift stress. These results are compared with data obtained during and after spaceflight. We conclude that the stress of HDT induces changes in immunological responsiveness that are strikingly similar to those arising from the stress of spaceflight.

Effect of a herbal yeast food supplement and long-distance running on immunological parameters.

The effect of a food supplement on immunological parameters of 16 long-distance runners was tested in a randomized, double-blind and placebo-controlled trial. The supplement comprised plasmolysed herbal yeast, malt, honey, and orange juice. No statistically significant differences between the two groups regarding the following variables were detected at three sessions at rest and immediately after a 21 km run: total and differential white blood cell counts, numbers of B- and T-cells and T-subpopulations, concanavalin-A-induced lymphocyte proliferation, serum levels of immunoglobulins, neopterin, IL-2 receptors, beta 2-microglobulin, complement factor b, c4 and c3c, and c1-inactivator. These findings suggest that the effects of the tested food supplement on these parameters are negligible with respect to improvements in the immunological status of long-distance runners. The changes observed immediately after the run had a transient character. In both groups, however, low lymphocyte counts, IgG subclass 2 levels and c1-inactivator levels were noted at rest, which indicate that the immune status of endurance athletes may be affected by training.

Research on Biolab, a multi-user facility for APM.

A study carried out by a team of seven scientists appointed by ESA resulted in the design of a biological laboratory "Biolab" for Columbus APM. The basis for the study were four pre-Phase A studies performed by industry on the assumption that 15 racks would be available to biology and biotechnology in the APM. Due to the constraints newly imposed by the Columbus project, only five racks are now allocated. The tasks of the Biolab scientific team were: (i) to define the scientific objectives of biological research in Columbus; (ii) to review the requirements of the industrial studies; and (iii) to design a multi-purpose facility compatible with the present constraints and satisfying the requirements of the biological investigations considered in the four studies. The Biolab team was able to define a facility capable of accommodating in five racks the following biological objects: small plants (up to 40 cm), insects like drosophila, frog eggs, single cells from animals, bacteria, slime molds and protozoa, as well as human physiology, but restricted to general diagnostic needs. The Biolab facility includes instruments and devices providing the capacity of holding and/or growing the organisms as well as to perform basic experimentation and a minimum essential diagnostic inflight. Within the growth unit the growth chambers/incubators are exchangeable, permitting the use of growth chambers of different sizes. The temperature will be adjustable to the requirements of the objects under investigation, i.e. either 20 or 37 degrees C. Thus a considerable level of flexibility will permit to investigate a broad spectrum of living systems.

Gravitational effects on mammalian cells.

In this paper we present first the results of our most recent investigations on gravitational effects on the activation of human lymphocytes: by immunoenzymatic staining and by using concanavalin A (Con A) coated to red blood cells (RBC) we demonstrate that the increase of activation measured at 10xg is due to a simultaneous activation of T- and B-lymphocytes whereas at 1xg only T-cells are stimulated. Conversely, activation of T-cells by chemical modification of the membrane with sodium periodate is depressed at 10xg. Secondly, experiments performed in the centrifuge as well as in the clinostat with Friend, K-562, and hybridoma cells show that each cell line develops its own adaptation reaction to gravitational stress.

Tetracycline in the treatment of malignant effusions: evidence for a cytostatic action of the decomposed drug.

During the in vitro growth of human carcinoma cell lines an inhibition of cell growth in media containing tetracycline was observed at a concentration which was about 1000 times below the one reached in the pleural fluid of malignant effusions after tetracycline instillation. During short time drug-cell contact only previously heated tetracycline showed growth inhibition like doxorubicin, a substance of similar structure and origin. Freshly prepared tetracycline inhibited cell growth only after several minutes of drug cell contact. Our observations in vitro suggest that decomposed tetracycline plays an important role in the control of malignant effusions.

Interactions of cytotoxic and other drugs: rapid cell culture assay.

In order to investigate the interactions of cytotoxic and other drugs, a cell culture assay was devised where changes in the ability of cytotoxic drugs to induce cytopathogenic effects can easily be visualized. A human mammary carcinoma cell line (BT 20) and a human hypernephroma cell line were used. Seventeen commonly used cytotoxic drugs were titrated in this assay. As an example of drug interactions the neutralization of nitrogen mustard, cis-dichlorodiammine-platinumII, and 4-hydroperoxycyclophosphamide by thiol-containing drugs shows that this assay is well suited to detect interactions of cytotoxic and other drugs.

Effects of 13-cis retinoic acid and Ara-C on differentiation and proliferation of non-promyelocytic acute myelogenous leukemia.

An alternative to a cell-kill strategy for eradication of acute myelogenous leukemia, is to restore normal differentiation. Vitamin A derivatives demonstrate differentiation-inducing activity both in vitro and in vivo on promyelocytic leukemic cells. We tested the ability of 13-cis retinoic acid to reduce proliferation and induce differentiation in 10 samples from patients with acute non-promyelocytic leukemia. DNA synthesis and leukemia colony formation were affected to varying degrees by a prolonged exposure to the vitamin A compound. Morphologically and cytochemically no differentiation was determined either after 48 h in suspension cultures or 7 additional days in semi-solid cultures. Alkaline leukocyte phosphatase, a biochemical marker of differentiation, was significantly increased in five samples. DNA synthesis in these samples was significantly reduced as compared to samples failing to express alkaline leukocyte phosphatase following 13-cis retinoic acid treatment. DNA synthesis of these same 5 samples was also strongly inhibited by Ara-C. Expression of alkaline leukocyte phosphatase following 13-cis retinoic acid exposure may be a useful indicator for cells amenable to 13-cis retinoic acid or Ara-C treatment.

The effects of interferon on granulopoiesis in vitro.

Colony formation by myeloid progenitor cells (CFU-c) in agar was inhibited to the same extent by heterogeneous human leucocyte IFN (IFN-Le) and 2 different cloned IFN-alpha 2 preparations, but approximately 10 times less by cloned IFN-alpha 1; cluster formation remained unaffected by any of the interferons. An anti-proliferative effect is suggested by both lower cell yield and DNA synthesis in IFN containing liquid cultures. Incubation of cells with IFN for 18 h prior to plating with colony stimulating factor (CSF) reduced colony formation, indicating an altered responsiveness of CFU-c to CSF. In IFN treated cultures no consistent block of morphological differentiation occurred, but granulocyte alkaline phosphatase activity was reduced. Thus, IFN may play a modulatory role on functional markers. Our results indicate that the effects observed with heterogeneous preparations are due to IFN and not to impurities and that various differentiation parameters are unequally affected by IFN.