Brian Crucian

Interferon-γ-inducing factor elicits antitumor immunity in association with interferon-γ production

Interferon-gamma-inducing factor (IGIF) is a novel cytokine that stimulates T-cell proliferation, augments natural killer (NK) cell lytic activity, and induces interferon-gamma (IFN-gamma) production in established type 1 T-helper (Th1) cells in the presence of anti-CD3 antibody. The in vitro induction of IFN-gamma by recombinant murine IGIF in these cells was more potent than that induced by murine interleukin-12 (IL-12) and occurred apparently independent of murine IL-12. Here we report that subcutaneous injection into mice of tumor cells transfected with murine IGIF complementary DNA (cDNA) resulted in > or = 10-fold increase of mitogen-stimulated IFN-gamma production in cultured splenocytes. In addition, IGIF-transfected Renca and K1735 tumor cells can be rejected in vivo. The IGIF antitumor effect was abrogated in mice that were sublethally irradiated or depleted of both CD4+ and CD8+ T cells but not in mice depleted of either subpopulation alone. The antitumor effect mediated by IGIF appears to be dependent on IFN-gamma production, because in vivo neutralization of IFN-gamma was accompanied by growth of IGIF-transfected tumors in 100% of the animals. Taken together, our results show that murine IGIF can elicit T-cell-dependent antitumor immunity associated with IFN-gamma induction.

Alterations in adaptive immunity persist during long-duration spaceflight

Background:It is currently unknown whether immune system alterations persist during long-duration spaceflight. In this study various adaptive immune parameters were assessed in astronauts at three intervals during 6-month spaceflight on board the International Space Station (ISS).AIMS:To assess phenotypic and functional immune system alterations in astronauts participating in 6-month orbital spaceflight.Methods:Blood was collected before, during, and after flight from 23 astronauts participating in 6-month ISS expeditions. In-flight samples were returned to Earth within 48 h of collection for immediate analysis. Assays included peripheral leukocyte distribution, T-cell function, virus-specific immunity, and mitogen-stimulated cytokine production profiles.Results:Redistribution of leukocyte subsets occurred during flight, including an elevated white blood cell (WBC) count and alterations in CD8+ T-cell maturation. A reduction in general T-cell function (both CD4+ and CD8+) persisted for the duration of the 6-month spaceflights, with differential responses between mitogens suggesting an activation threshold shift. The percentage of CD4+ T cells capable of producing IL-2 was depressed after landing. Significant reductions in mitogen-stimulated production of IFNγ, IL-10, IL-5, TNFα, and IL-6 persisted during spaceflight. Following lipopolysaccharide (LPS) stimulation, production of IL-10 was reduced, whereas IL-8 production was increased during flight.Conclusions:The data indicated that immune alterations persist during long-duration spaceflight. This phenomenon, in the absence of appropriate countermeasures, has the potential to increase specific clinical risks for crewmembers during exploration-class deep space missions.

Assessment of intracellular TAP‐1 and TAP‐2 in conjunction with surface MHC class I in plasma cells from patients with multiple myeloma

Immunotherapy involving cytotoxic T lymphocytes (CTLs) is an attractive alternative for treatment of various malignancies, including multiple myeloma. For tumour cells to be recognized and killed by CTLs they must express cell surface major histocompatibility complex (MHC) class I molecules and the transporter associated with antigen processing (TAP). However, loss of MHC class I and the TAP protein are common among several types of solid tumours. This study assessed the expression of TAP protein (by intracellular flow cytometry) and cell surface MHC class I molecules in three human myeloma cell lines as well as the plasma cell population (CD38+ bright) in bone marrow specimens from 13 multiple myeloma patients. In all of the patients, 100% of the plasma cell population expressed both the TAP subunits and cell surface MHC class I molecules, but at varying intensities. Both TAP and MHC class I were also expressed in the three myeloma lines. Additionally, the function of the antigen transport machinery was evaluated by a peptide transporter assay in the three myeloma lines. TAP transporter activity was readily detectable in two out of three myeloma lines, whereas the diminished activity in the third cell line was completely restored by co‐culturing with recombinant interferon‐γ (rIFN‐γ).

Bing de ling, a Chinese herbal formula, stimulates multifaceted immunologic responses in mice.

Bing de ling is a Chinese herbal formula most commonly used in complementary medical settings against viral disorders. We have found that bing de ling potentiates upregulation of immune activity when administered to mice in dosages proportional to those used clinically. These mice demonstrated significant elevation of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) production in splenocytes and enhancement of macrophage, natural killer cell, and lymphokine-activated killer cell cytotoxicity. These data are consistent with bing de lings clinically observed efficacy against viruses and identify the formula as a promising candidate for clinical trials against diverse diseases that may respond to increased immunologic activity.

Immune System in Space: General Introduction and Observations on Stress-Sensitive Regulations

Numerous studies have indicated that spaceflight results in dysregulation of the human immune system. This phenomenon has been well documented following flight, where landing and re-adaptation are significant stressors. There is some limited in-flight data which indicates that immune changes do occur during spaceflight. Persistent decrements in the function of specific innate or adaptive immune cells, or alterations in cytokine production profiles, could result in clinical risk to crewmembers participating in exploration-class space missions. This chapter will introduce the immune system and innate versus adaptive immunity. How stress and spaceflight affects the immune system will be discussed, including alterations in the peripheral blood levels of specific immune cells during spaceflight. Subsequent chapters will explore the concepts of spaceflight, immunity, stress, and latent herpes virus reactivation in more detail.

Flow Cytometry Methods to Monitor Immune Dysregulation Associated with Spaceflight

Numerous studies have demonstrated that immune system dysregulation occurs both during and following spaceflight. The immune system is inherently complex, and there are many distinct subsets of immune cells, each with unique functional capabilities. Granulocytes phagocytose non-self particles, NK cells kill target cells in a nonspecific fashion, T cells kill specific target cells, and B cells manufacture plasma antibodies. There are other cell types which have overlapping functions, and all of these cell populations communicate and mediate their function via cytokine/chemokine crosstalk. Flow cytometry is useful as a versatile platform from which both the number and functional potential of many immune cell populations may be evaluated. Percentages of peripheral leukocyte subsets may be directly measured by flow cytometry, as well as intracellular antigens, DNA content, and other inherent cellular characteristics. Additionally, by culturing immune cells prior to flow cytometry analysis, various functional characteristics such as activation marker expression, cytokine secretion, phagocytosis, and target cell killing may be measured. Using this versatility, many studies have used flow cytometry techniques to investigate spaceflight-associated immune dysregulation. This chapter discusses flow cytometry assays shown to identify immune alterations associated with spaceflight as well as newer cytometry techniques, which may be of use in flight studies. The development of an in-flight flow cytometer for both clinical and research applications during long duration space missions will also be discussed.

Adaptive Immunity and Spaceflight

Spaceflight causes alterations in human immunity, a finding which has been well documented immediately following spaceflight. Limited in-flight studies have also confirmed that to some degree immunity is compromised during spaceflight. A comprehensive understanding of the nature of these immune changes is lacking. This chapter reviews the current evidence regarding spaceflight effects on the function of the adaptive immune system, and speculates on potential adverse clinical outcomes and likely countermeasures. Potential causes for these alterations are discussed elsewhere in this volume ( Chap. 9), as are spaceflight effects on the function of the innate immune system ( Chap. 10).