title: Elevation of IgE-binding factors in serum of patients with B cell-derived chronic lymphocytic leukemia.
abstract: One hundred nineteen sera from patients with various lymphoproliferative diseases and normal sera were tested by a solid-phase radioimmunoassay (RIA) for their content in IgE-binding factor (IgE-BF), a soluble glycoprotein binding to IgE and derived from low-affinity IgE receptors (Fc epsilon R). Fc epsilon R, recently identified as CD23, are known to be expressed on the surface of B cells at the intermediate stage of differentiation. The results indicate that in all cases of chronic lymphocytic leukemia (CLL) tested (n = 40), IgE-BF levels (45 to 8,656 U/mL) were 3-fold to 500-fold higher than in 24 controls (15.5 +/- 2 U/mL). With a few exceptions, serum IgE-BF levels could differentiate patients with CLL from those with other leukemias or lymphomas. In vitro studies indicated that B lymphocytes isolated from CLL patients produced 8 to 50 times more IgE-BF than did normal B cells (P less than 0.001). IgE-BF level was correlated with the Rai stage of the disease (P = 0.002) and the lymphocyte count (P = 0.041). IgE-BF was purified to homogeneity from one CLL serum sample by a combination of affinity chromatography and reverse-phase high-performance liquid chromatography (HPLC). this IgE-BF proved identical to IgE-BF isolated from the culture supernatant of RPMI 8866 cells, a B lymphoblastoid cell line bearing Fc epsilon R and secreting IgE-BF. Indeed, the two molecules had the same mol wt (25 to 27 kd), the same isoelectric point, and the same tryptic map. We suggest that determination of serum IgE-BF might prove useful for clinical monitoring of CLL.
mesh_terms: D001402:B-Lymphocytes; D002454:Cell Differentiation; D006801:Humans; D007073:Immunoglobulin E / Q000378:metabolism*; D007945:Leukemia, Lymphoid / Q000097:blood*; D008222:Lymphokines / Q000097:blood*; D008232:Lymphoproliferative Disorders / Q000097:blood; D009363:Neoplasm Proteins / Q000097:blood; D029584:Prostatic Secretory Proteins; D011961:Receptors, Fc / Q000378:metabolism; D017455:Receptors, IgE
chemical_list: D008222:Lymphokines; D009363:Neoplasm Proteins; D029584:Prostatic Secretory Proteins; D011961:Receptors, Fc; D017455:Receptors, IgE; C043076:beta-microseminoprotein; C013059:immunoglobulin-binding factors; D007073:Immunoglobulin E