The effect of physiological and pharmacologically induced thymus involution was studied in 12-week-old female C57BL mice. Thymus involution was estimated by measurement of the thymus weight and the ability of thymocytes to induce a graft-versus-host (GvH) reaction at 48 h after delivery or drug administration in comparison with control (virgin, saline-treated) mice. The thymus weight and immuno...

AIMS Electromagnetic fields (EMFs) can act as inducers or mediators of stress response through the production of heat shock proteins (HSPs) that modulate immune response and thymus functions. In this study, we analyzed cellular stress levels in rat thymus after exposure of the rats to a 2.45 GHz radio frequency (RF) using an experimental diathermic model in a Gigahertz Transverse Electromagneti...

A progressive decrease of the restoring effectivity of syngeneic or allogeneic thymus and functional thymoma grafts was observed when the treatment of neonatally thymectomized mice was delayed. Early treatment (5-20 days postthymectomy) was effective, while the number of restored animals was markedly decreased after late treatment (30-50 days postthymectomy). Similar results were obtained with ...

Corticosteroids suppress the humoral antibody response of mice to sheep erythrocytes. This response depends on interactions between thymus-derived helper cells and bone marrow-derived antibody-forming cell precursors (AFC precursors). Previous experiments had shown that spleen cells (a mixture of thymus-derived and marrow-derived cells) were sensitive to corticosteroids while AFC precursors in ...

Cyclic adenosine 3':5'-monophosphate (cyclic AMP) levels were slightly increased in preleukemic AKR mouse thymus cells, compared with nonleukemic thymus cells, but were markedly reduced in leukemic cells. Adenylate cyclase activity rose during the preleukemic and leukemic phases of leukemogenesis. Although the drop of epinephrine-induced stimulation of thymus adenylate cyclase in the preleukemi...

Hematopoietic precursors continuously colonize the thymus where they give rise mainly to T cells, but also to B and dendritic cells. The lineage relationship between these three cell types is unclear, and it remains to be determined if precursors in the thymus are multipotent, oligopotent, or lineage restricted. Resolution of this question necessitates the determination of the clonal differenti...

Congenital osteopetrosis in the mutant rat "op" is accompanied by early atrophy of the thymus gland. The response of thymocytes to concanavalin A and phytohemagglutinin P was greatly diminished at age 28 days, even before pronounced thymic atrophy could be detected. The response of spleen cells to mitogens that stimulate thymus-derived (T) and bone-marrow-derived (B) cells was diminished as ear...

A synergistic interaction in the proliferative response to alloantigen has been previously noted when intact thymus cells are cultured with post-thymic (peripheral) lymphoid cells. In the present study, a factor extracted from the thymus has been shown to similarly enhance the reactivity of syngeneic lymph node cells and thus to retain the amplifier activity of intact thymus cells. The factor h...

Eosinophils differentiate and mature in the thymus, outside of bone marrow, healthy individuals. Locally developed thymic eosinophils may contribute to maturation selection human thymocytes.

Although T cells arise in the thymus, migration of mature postthymic T cells back to the thymus is very limited in adult mice and is restricted to activated cells. In neonates, by contrast, we present evidence that circulating CD4+ and CD8+ T cells with a naive/resting phenotype readily enter the thymus after intravenous injection and remain there for prolonged periods. The migration of resting...