OBJECTIVETo study the quantity and function of bone marrow (BM) T follicular helper (Tfh) cells of the cytopenia patients with positive bone marrow mononuclear cells (BMMNC)- Coombs test (also known as immuno-related pancytopenia, IRP), and explore the role of Tfh cells in the pathogenesis of IRP.

METHODSForty- three untreated IRP patients, 47 recovered IRP patients and 25 healthy donors were enrolled in this study. The percentages of Tfh cells, Tfh-related molecules ICOS, CD40L, IL-21 and Bcl-6 in BM were investigated by flow cytometry and semiquantitive RT-PCR.

RESULTSThe ratio of CD4⁺CXCR5⁺/CD4⁺ cells of untreated IRP patients [(28.79 ± 19.70)%] was significantly higher than that of recovered IRP patients [(21.15 ± 12.81)% ] and normal controls ([ 13.42 ± 6.72)% ](P<0.05). The ratio of CD4⁺CXCR5⁺ICOS⁺/CD4⁺CXCR5⁺ cells of untreated IRP patients [(5.05 ± 4.71)% ] was significantly higher than that of recovered IRP patients [(2.96 ± 2.89)% ] and normal controls [(2.99 ± 2.23)% ] (P<0.05). The ratio of CD4⁺CXCR5⁺CD40L⁺/CD4⁺CXCR5⁺ cells of untreated IRP patients [(5.87 ± 4.14)%] and recovered IRP patients [(6.52±5.47)%] were significantly higher than that of normal controls [(2.93 ± 2.92)%] (P<0.05). The ratio of intracytoplasmic CD4⁺CXCR5⁺IL-21⁺/CD4⁺CXCR5⁺ cells of untreated IRP patients [(8.20 ± 7.41)% ] and recovered IRP patients [(6.30 ± 6.03)% ] were significantly higher than that of normal controls [(3.43 ± 3.40)%] (P<0.05). The relative expressions of Bcl-6 mRNA in BMMNC were 0.625 ± 0.248, 0.485 ± 0.253, 0.306 ± 0.210 in three groups, respectively. The differences between untreated IRP patients, recovered IRP patients and normal controls were significant (P<0.05).

CONCLUSIONThere exists increased quantity and hyperfunction of Tfh cells in the IRP patients, they may play important role in the pathogenesis of IRP. Tfh cells and their related effector molecules could be a potential therapeutic target for the disease.