Find in Library

<p>Abstract</p> <p>Background</p> <p>There is a growing body of evidence to suggest that CD8⁺T lymphocytes contribute to local allergen-induced eosinophilic inflammation. Since bone marrow (BM) responses are intricately involved in the induction of airway eosinophilia, we hypothesized that CD8⁺T lymphocytes, as well as CD4⁺T lymphocytes, may be involved in this process.</p> <p>Methods</p> <p>Several approaches were utilized. Firstly, mice overexpressing interleukin-5 (IL-5) in CD3⁺T lymphocytes (NJ.1638; CD3^IL-5+mice) were bred with gene knockout mice lacking either CD4⁺T lymphocytes (CD4^-/-) or CD8⁺T lymphocytes (CD8^-/-) to produce CD3^IL-5+knockout mice deficient in CD4⁺T lymphocytes (CD3^IL-5+/CD4^-/-) and CD8⁺T lymphocytes (CD3^IL-5+/CD8^-/-), respectively. Secondly, CD3⁺, CD4⁺and CD8⁺T lymphocytes from naïve CD3^IL-5+and C57BL/6 mice were adoptively transferred to immunodeficient SCID-bg mice to determine their effect on BM eosinophilia. Thirdly, CD3^IL-5+, CD3^IL-5+/CD8^-/-and CD3^IL-5+/CD4^-/-mice were sensitized and allergen challenged. Bone marrow and blood samples were collected in all experiments.</p> <p>Results</p> <p>The number of BM eosinophils was significantly reduced in CD3^IL-5+/CD8^-/-mice compared to CD3^IL-5+mice and CD3^IL-5+/CD4^-/-mice. Serum IL-5 was significantly higher in CD3^IL-5+/CD4^-/-mice compared to CD3^IL-5+mice but there was no difference in serum IL-5 between CD3^IL-5+/CD4^-/-and CD3^IL-5+/CD8^-/-mice. Adoptive transfer of CD8⁺, but not CD4⁺T lymphocytes from naïve CD3^IL-5+and C57BL/6 mice restored BM eosinophilia in immunodeficient SCID-bg mice. Additionally, allergen challenged CD3^IL-5+/CD8^-/-mice developed lower numbers of BM eosinophils compared to CD3^IL-5+mice and CD3^IL-5+/CD4^-/-mice.</p> <p>Conclusion</p> <p>This study shows that CD8⁺T lymphocytes are intricately involved in the regulation of BM eosinophilopoiesis, both in non-sensitized as well as sensitized and allergen challenged mice.</p>