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Human B Lymphocytes (human + b_lymphocyte)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Complement receptors type 1 (CR1, CD35) and 2 (CR2, CD21) cooperate in the binding of hydrolyzed complement factor 3 (C3i) to human B lymphocytes

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 12 2003
Graham, Quinton Leslie, Robert
Abstract The C3b-binding receptor, CR1/CD35, supports CR2/CD21-mediated activation of complement by human B lymphocytes, possibly by associating with CR2 to promote or stabilize the binding of hydrolyzed C3 (C3i), the primary component of the AP convertase, C3i-Bb. To evaluate this hypothesis, we examined the uptake kinetics and binding equilibria for C3i dimer interaction with human blood cells in the absence and presence of CR1- and CR2-blocking mAb. C3i displayed dual uptake kinetics to B lymphocytes, comprising of rapid binding to CR1 and slower binding to CR2. The forward rate constants (k1) for CR1 and CR2, operating independently, differed ca. 9-fold (k1=193±9.4 and 22.2±6.0×103,M,1s,1, respectively). Equilibrium binding of C3i to B lymphocytes was also complex, varying in strength by ca. 13-fold over the C3i concentration range examined. The maximum association constant (Ka,,max=109±27.2×107,l/mole) was ca. 9- and 6-fold greater, respectively, than those for CR1 or CR2 acting alone (Ka=13.2±5.3 and 18.5±3.5×107,l/mole). The high avidity of the CR1-CR2 complex for C3i is consistent with its rates of C3i uptake and release being determined by CR1 and CR2, respectively. [source]

A new Groucho TLE4 protein may regulate the repressive activity of Pax5 in human B lymphocytes

IMMUNOLOGY, Issue 4 2002
Michèle Milili
Summary During mouse B-cell development, Pax5 is an essential transcription factor that acts as an activator of B-cell-specific genes and as a repressor of alternative lineage fates. The repressive function is mediated by the recruitment of members of the Groucho co-repressor family. Using an RNA display approach, we have isolated a transcript, called QD, specifically expressed in human pro-B and pre-B cells, which is derived from the human Groucho TLE4 gene. The QD transcript contains the first four TLE4 exons and an intronic sequence 3, of exon 4, demonstrating that QD is a splice variant of TLE4. The putative resulting protein of 94 amino acids corresponds to approximately half of an N-terminal tetramerization domain. We also show specific expression of TLE4 transcripts in human B cells and of TLE4 proteins in B-cell nuclei. Moreover, we demonstrate that recombinant QD protein binds to the TLE4 Q domain and is able to abolish the TLE4/Pax5 interaction. Thus, QD could act as a negative regulator of TLE4 function, in early B-cell differentiation. [source]

An efficient method for the rapid establishment of Epstein-Barr virus immortalization of human B lymphocytes

CELL PROLIFERATION, Issue 4 2003
H.-M. Oh
Several methods have been developed for the immortalization of B lymphocytes by Epstein-Barr virus (EBV). We developed an efficient method which reduces the time from culture initiation to immortalization and cryopreservation. Two infections of EBV to lymphocytes, and the use of phorbol ester-induced EBV stock significantly improved immortalization efficiency and reduced the time between initiation and immortalization and cryopreservation. The resulting cell bank was used to produce DNA for genetic studies focusing on the genes involved in immune and autistic disorders. [source]