title: B cells expressing CD5 antigen are markedly increased in peripheral blood and spleen lymphocytes from patients with immune thrombocytopenic purpura.
abstract: By two-colour flow cytometric analysis, we examined the proportion of B lymphocytes bearing CD5 cell surface antigen (CD 5+ B cells), which are capable of producing autoantibodies, both in peripheral blood and spleen from patients with chronic immune thrombocytopenic purpura (ITP). The percentage of CD5+ B cells in peripheral blood lymphocytes (PBLs) was significantly increased (P less than 0.005) in patients with ITP (3.7 +/- 2.2%, n = 30) as compared with normal controls (1.7 +/- 0.7%, n = 28). However, there was no correlation between the percentages of circulating CD5+ B cells and platelet counts. The percentage of splenic CD5+ B cells in ITP patients was much more increased (9.0 +/- 4.5%, n = 9), P less than 0.005) compared with that of other disorders (3.2 +/- 0.5%, n = 5). Furthermore, isolated splenic CD5+ B cells from two out of five ITP patients produced high levels of IgM-type, platelet-bindable antibodies (PBIgM) after stimulation with Staphylococcus aureus Cowan I (SAC), while CD5- B cells isolated from the same spleen or splenic CD5+ B cells from other non-autoimmune disorders failed to produce significant amount of PBIgM. In three ITP patients, no increase in PBIgM was detected despite SAC stimulation. The increased proportion of CD5+ B cells in peripheral blood and spleen, and their ability to produce anti-platelet antibodies indicate that they are directly involved in the autoimmune pathogenesis in ITP.
authors.affiliation: Second Department of Internal Medicine, Osaka University Medical School, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Mizutani
authors.forename: T
authors.initials: T
authors.lastname: Furubayashi
authors.forename: H
authors.initials: H
authors.lastname: Kashiwagi
authors.forename: S
authors.initials: S
authors.lastname: Honda
authors.forename: H
authors.initials: H
authors.lastname: Take
authors.forename: Y
authors.initials: Y
authors.lastname: Kurata
authors.forename: T
authors.initials: T
authors.lastname: Yonezawa
authors.forename: S
authors.initials: S
authors.lastname: Tarui
mesh_terms: D000328:Adult; D000368:Aged; D015703:Antigens, CD / Q000032:analysis*; D001323:Autoantibodies / Q000096:biosynthesis; D001327:Autoimmune Diseases / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D001792:Blood Platelets / Q000276:immunology; D018956:CD5 Antigens; D002908:Chronic Disease; D005260:Female; D006801:Humans; D007075:Immunoglobulin M / Q000096:biosynthesis; D008297:Male; D008875:Middle Aged; D011696:Purpura, Thrombocytopenic / Q000276:immunology*; D013154:Spleen / Q000276:immunology*
chemical_list: D015703:Antigens, CD; D001323:Autoantibodies; D018956:CD5 Antigens; D007075:Immunoglobulin M