Interleukin 1beta as stimulator of the rat thymus

Neuro-immune modulation of the thymus microenvironment (review)

The thymus is the primary site for T-cell lympho-poiesis. Its function includes the maturation and selection of antigen specific T cells and selective release of these cells to the periphery. These highly complex processes require precise parenchymal organization and compartmentation where a plethora of signalling pathways occur, performing strict control on the maturation and selection processes of T lymphocytes. In this review, the main morphological characteristics of the thymus microenvironment, with particular emphasis on nerve fibers and neuropeptides were assessed, as both are responsible for neuro-immune‑modulation functions. Among several neurotransmitters that affect thymus function, we highlight the dopaminergic system as only recently has its importance on thymus function and lymphocyte physiology come to light.

Effects of mistletoe extract on murine thymocytes in vivo and on glucocorticoid-induced cell count reduction

BACKGROUND

Mistletoe extracts are widely used in cancer patients due to their cytostatic and immunomodulatory effects. Essential components include mistletoe lectins which act as biomodulators with proinflammatory and apoptosisinducing effects. This study investigates the acute and longterm effects of standardized mistletoe extract (Iscador(R) M spec 5 mg) on thymocyte subpopulations and peripheral T-cells using a murine (Balb/c) model.

MATERIALS AND METHODS

Using cell surface CD4/CD8 staining and flow cytometry, we followed the changes in CD4-CD8- double-negative (DN), CD4(+)CD8(+) double-positive (DP) and CD4(+) or CD8(+) single-positive (SP) T-cells 24 h after single or repeated injections of 3 different dilutions (1:12, 1:60, 1:300) corresponding to 2.1, 0.42 and 0.08 mg/kg of Iscador. Thymocyte apoptosis was detected by flow cytometry using Annexin V and propidium iodide.

RESULTS

24 h after a single injection of the 2 lower doses, the number of DN thymocytes increased significantly with an enhanced ratio of apoptotic cells. Following administration of the lowest dose, in peripheral blood the CD4(+)/CD8(+) ratio was elevated. In the long-term trial, Balb/c mice were treated twice a week with 3 different doses of Iscador +/- 20 mg/kg of dexamethasone (DX), resulting in significantly enhanced DN thymocytes and elevated levels of apoptotic cells after treatment with the 2 lower doses. Iscador also inhibited the DX-induced reduction in the thymic DN cell count, as well as the DX-induced decrease in the CD4(+)/CD8(+) ratio and CD4(+) in the peripheral blood.

CONCLUSION

Our results suggest that standardized mistletoe extract modulates proliferation and apoptosis of thymocytes in a dose-dependent manner and may act lymphoprotective during DX treatment.

Galactoside-specific plant lectin, Viscum album agglutinin-I induces enhanced proliferation and apoptosis of murine thymocytes in vivo

Galactoside-specific plant lectin, Viscum album agglutinin-I (VAA-I) has been shown to act as a biomodulator with proinflammatory and apoptosis-inducing effects, however its cellular targets and mechanism of immunobiological action in vivo are less well understood. Therefore, in the present work the short- and long-term in vivo effects of VAA-I on thymocyte subpopulations and peripheral T cells were tested using a murine (Balb/c) model. Cell surface CD4/CD8 staining and flow cytometry allowed us to follow the changes of thymocyte subpopulations: CD4-CD8- double negative (DN), CD4+CD8+ double positive (DP), CD4+ or CD8+ single positive (SP) and mature peripheral T cells after single or repeated injections with low doses of VAA-I. The apoptosis of the cells was detected by flow cytometry using propidium iodide (PI) and Annexin V staining. To detect the short-term effects of the lectin, the animals were investigated 24 h after a single injection of 1 or 30 ng/kg body weight (BW) VAA-I+/-1 mg/kg Dexamethasone (DX). The total number of mature CD8+ SP thymocytes increased significantly with an enhancement of the ratio of apoptotic cells. In contrast, in the blood samples an elevated CD4/CD8 ratio was found. In the next trial, Balb/c mice were treated twice weekly with 1 or 30 ng/kg VAA-I+/-1 mg/kg DX for 3 weeks. The total cell count of thymocytes showed significant increases after both doses of VAA-I, but an elevated percentage of apoptotic cells was found only after treatment with 30 ng/kg VAA-I. SP thymocytes revealed higher increases in lectin-induced apoptosis than DN or DP cells. In addition, both lectin doses significantly inhibited the DX-induced reduction of all thymocyte subpopulations investigated. In conclusion, our data suggest that VAA-I is able to modulate the maturation of thymocytes in vivo.