Cloning and expression of the cDNA coding for a human lymphocyte IgE receptor.

Abstract

Low‐affinity receptors (Fc epsilon R) and secreted factors (IgE‐BF) which bind to immunoglobulins of the IgE isotype play a key role in the regulation of human IgE synthesis. We report here the cloning of a cDNA coding for the Fc epsilon R of the human B‐lymphoblast cell line RPMI 8866. The nucleotide sequence of this cDNA predicts a polypeptide with 321 amino acids and a mol. wt of 36,281 daltons. A functional Fc epsilon R capable of binding IgE was expressed in Chinese hamster ovary cells after stable transformation with the cDNA which had been cloned into a mammalian expression vector. Amino acid sequence analysis of IgE‐BF purified from RPMI 8866 cells revealed an amino‐terminal sequence of 19 residues which coincides with the predicted amino acid sequence of the Fc epsilon R, starting at residues 148 and 150. A computer search with the translated amino acid sequence of the Fc epsilon R revealed a domain of 120 amino acids having striking homology to the human asialoglycoprotein receptors.

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

“…We have previously reported that enriched populations of B lymphocytes from blood produce factors (3,5) that promote in vitro development of blood-and bone marrow-derived CD7 + CD2 -precursors. Comparing the biochemical characteristics of this B cell-derived activity (3) to known B cell-derived molecules, we found its striking homology to soluble CD23 (sCD23 ; sFcERII) (6,7) . Using recombinant sCD23 (rsCD23) (7), we then assayed the effect of this molecule alone or with rIL-1 and/or rIL-2 on purified CD7 + thymic precursors .…”

Soluble CD23 Monomers Inhibit and Oligomers Stimulate IGE Synthesis in Human B Cells

“…CD23, a 45-kDa type II integral membrane protein, is unique among Ig receptors in belonging to the animal C-type lectin rather than the Ig superfamily (10,11). The extracellular sequence comprises the lectin "head," N-terminal "stalk," and C-terminal "tail."…”

Identification of DMC1, a novel gene in the TOC region on 17q25.1 that shows loss of expression in multiple human cancers

“…These include CD40L (Hollenbaugh et al 1992), CD26 (Hegen et al 1990;Tanaka et al 1992), CD23 (Ikuta et al 1987;Ludin et al 1987), NKR-P1 (Yokoyama and Seaman 1993), and FasL (Suda et al 1993). DMC1 has the "Pro-Pro-X-Pro" motif near the transmembrane domain.…”