[Pathological effects and clinical significance of eosinophils in autoimmune-related hematocytopenia]

To observe the pathological effects induced by eosinophils (EOS) in the process of cellular damage in immune-related hematocytopenia (IRH) and elucidate the immunologic mechanism and clinical significance of EOS.

Enzyme-linked immunosorbent assay (ELISA) was performed to determine the serum concentrations of interleukins (IL)-2, IL-4, IL-5, IL-6, IL-12 and IL-17 in 117 IRH patients from February 2008 to February 2012 in our hospital. Their quantity, activity, peroxidase (POX) and HLA-DR expression of EOS were observed and analyzed. Immunofluorescent staining was used for detecting anti-human immunoglobulin (IgG) on the surface of hematopoietic cell and the expressions of intercellular adhesion molecule-1 (ICAM-1), Fcγ receptor II (FcγRII), mannose receptor (MR), IL-5 receptor (IL-5R), IL-12, IL-12 receptor (IL-12R), IL-17A and IL-17 A receptor (IL-17RA) on EOS. TdR incorporation method was employed to determine the capability of antigen presentation and IL-17 mRNA expression examined by reverse transcription-polymerase chain reaction (RT-PCR).

The serum levels of IL-4, IL-5, IL-6, IL-12 and IL-17 were (170.9 ± 14.7), (112.9 ± 8.2), (131.8 ± 13.8), (339.2 ± 26.1) and (42.5 ± 2.2) ng/L in patient group versus (60.3 ± 11.0), (34.1 ± 2.2), (91.0 ± 12.3), (94.0 ± 3.3) and (20.0 ± 1.1) ng/L in control group respectively. All incremental percentages of IL-5, IL-12 and IL-17 were 100% (117/117) and they were correlated with disease. Diastrophic EOS could be found in marrow of patient with decreased leucocyte with HLA-B27(+). Hematopoietic cells were adhered, captured and phagocytized actively by activated EOS. Activated EOS showed strongly positive POX while POX of neutrophils attacked by EOS became weakened. Activated EOS could express HLA-DR and played a role in antigen presentation. EOS could secrete cytokine IL-17 through a transcription of IL-17 mRNA. And EOS could also express ICAM-1, FcγRII, MR, IL-5R and IL-12, IL-17A, IL-17RA.

Capable of expressing or secreting various cytokines and molecules, EOS have immunological functions of adhering, capturing and phagocytizing pathological hemocytes. It also participates in pathogenic process of IRH. Thus EOS is probably an important immune effector cell in the process of in situ marrow damage.