ABSTRACT
The cytokines IL-5, IL-3, and GM-CSF are crucial for eosinophil development, survival, and function. To better understand their role in non-IgE-mediated eosinophilic diseases, we investigated plasma levels of these cytokines as well as cytokine expression in peripheral blood T cells. While we did not find any evidence for an involvement of T-cell-derived GM-CSF, some of these patients did show an increased proportion of IL-5- or IL-3-producing CD4(+) T cells. However, in a significant proportion of patients, IL-5-producing CD8(+) T cells, so-called Tc2 cells, which in healthy donors can only be detected at very low levels, were prominent. Furthermore, increased IL-3 production by CD8(+) T cells was also observed, strongly supporting the notion that CD8(+) T cells, not just CD4(+) T cells, must also be considered as a potential source of the cytokines promoting eosinophilia.
Subject(s)
CD8-Positive T-Lymphocytes/metabolism , Eosinophilia/metabolism , Interleukin-3/biosynthesis , Interleukin-5/biosynthesis , CD4-Positive T-Lymphocytes/immunology , CD4-Positive T-Lymphocytes/metabolism , CD8-Positive T-Lymphocytes/immunology , Eosinophilia/immunology , Humans , Immunoglobulin E/immunology , Interleukin-3/blood , Interleukin-5/bloodABSTRACT
Peptides displayed by antigen presenting cells in the thymus shape the T cell repertoire. We investigated the antigen processing machinery of the MHC class II presentation pathway and describe the differential expression of lysosomal proteases in compartments of the thymus and the peripheral lymphoid tissue. Overexpression of certain proteases found in the thymus and thymoma associated with myasthenia gravis is likely to affect tolerance induction and may promote the generation autoreactive CD4(+) T helper cells.