Fc epsilon receptor, a specific differentiation marker transiently expressed on mature B cells before isotype switching.

Abstract

B lymphocytes originate from pluripotent hematopoietic stem cells and differentiate into antibody-secreting cells through multistep differentiation stages, such as pre-B cells, immature B cells with surface IgM, and mature B cells with surface IgM and IgD . A number of human B cell antigens have been defined by in Abs (I-10) . However, most B cell-specific mAbs, except for antibodies against plasma cells (5) and activated B cells (9,10), are known to recognize cells of the B lineage at a wide range of differentiation stages from pre-B cells to mature B cells . It has therefore been difficult to identify B cells at a specific differentiation stage by using such B cell-specific mAbs.Several previous studies (11)(12)(13)(14) have shown the expression of FcER on a certain percentage (1-5%) of circulating B or T cells using the rosette method with IgE-conjugated ox red blood cells (ORBC).t Our previous study (15) with FcER-specific mAbs with several different epitope specificities showed that >50% of circulating B cells express FcER on their surface, while T cells do not display this receptor, even with T cells from patients with hyper-IgE syndrome . The discrepancy in the results may be due to the difference in the sensitivity of the assay system and the antibodies used. In the present study, the distribution of FcER + cells was studied in various lymphoid tissues, and the results show that FcER is a B cell-specific phenotype marker, the expression of which is strictly correlated with the differentiation stage of B cells, especially with the isotype switching in B cells . Materials and MethodsAntibodies . Human IgE(PS) was the same preparation as described previously (16 1456Fce RECEPTOR AND ISOTYPE SWITCHING F(ab)' 2 fragment of goat anti-human IgD and FITC-F(ab)' 2 fragment of goat anti-human IgA were purchased from Tago Inc . (Burlingame, CA). FITC-anti-B1 was from Coulter Immunology (Hialeah, FL) . An anti-human IgM mAb was a kind gift from Dr. M . Sugi (Yamasa Shoyu Co., Ltd, Tokyo, Japan) . An anti-human IgE mAb was the same preparation as described previously (17). The anti-FcER mAbs 1-7, 3-5, and 8-30, which are of IgG2b, IgG 1, and IgM, respectively, were produced by hybridization ofP3U 1 myeloma with spleen cells from BALB/c mice immunized with RPMI-8866 cells (15). Two antibodies (1-7 and 8-30) recognized the epitope close to IgE-binding site of Fc(R and blocked IgE binding to 8866 lymphoblastoid cells . The antibody 3-5 recognized a different epitope on FccR, and could not block IgE binding to 8866 cells . These antibodies precipitated 25,000 and 46,000 Mr polypeptides under reducing and nonreducing conditions . The mAbs were purified from ascites by 50% saturated ammonium sulfate precipitation followed by gel filtration using Sepharose 6 B (Pharmacia Fine Chemicals, Uppsala, Sweden) for IgM class, or by ion-exchange chromatography using QAE-Sephadex (Pharmacia Fine Chemicals) for IgGI and IgG2b classes . Some of the antibodies were conjugated with biotin or FITC as described (18,19) . Some of the antib...

Soluble CD23 (Fc epsilon RII) and interleukin 1 synergistically induce early human thymocyte maturation.

“…CD23 was initially considered as a B cell differentiation marker (10) . Subsequently, this molecule was shown to be identical to the low affinity receptor for IgE (Fcc-RII), which may also be expressed on monocytes/macrophages, eosinophiles, platelets, some T cells, and epidermal Langerhans cells (6).…”

Functional B-cell response in intrahepatic lymphoid follicles in chronic hepatitis C

“…The CD23 molecule is expressed on some subsets of mature GC-B cells 30 and is important for survival and differentiation of GC-B cells in the follicles. 31 CD23 was diffusely stained in the GCs of lymph nodes and was closely related to IgM ϩ cells in the GCs (Fig.…”

Increased production of soluble CD23 in rheumatoid arthritis, and its regulation by interleukin‐4

“…I), selectively expressed on circulating B cells with surface IgD and IgM (2,3). This 45-kd transmembrane glycoprotein is also present on a variety of cell types, including T lymphocytes, monocytes (41, platelets (51, and eosinophils (6).…”