A high density CHO-S transient transfection system: Comparison of ExpiCHO and Expi293.

Chinese Hamster Ovary (CHO) cells are the principal mammalian host used for stable cell line generation and biotherapeutic protein production. Until recently, production of milligrams to grams of protein in CHO transient systems was challenging. As such, Human Embryonic Kidney (HEK293) cells are the most common mammalian cell type used for transient transfection.

Scalable transient protein expression.

Transient transfection is a well-established method to rapidly express recombinant proteins from mammalian cells. Accelerating activity in biotherapeutic drug development, demand for protein-based reagents, vaccine research, and large initiatives in structural and functional studies of proteins have propelled the need to generate moderate to high amounts of recombinant proteins and other macromolecules in a flexible and rapid manner. Progress over the last 10-15 years has demonstrated that transient transfections can be reliably and readily scaled up to handle milliliters to tens of liters of cells in suspension culture and obtain milligrams to grams of recombinant protein in a process that requires only days to weeks.

Drug-induced thrombocytopenia.

Drug-induced thrombocytopenia (DIT) is a relatively common clinical disorder. It is imperative to provide rapid identification and removal of the offending agent before clinically significant bleeding or, in the case of heparin, thrombosis occurs. DIT can be distinguished from idiopathic thrombocytopenic purpura, a bleeding disorder caused by thrombocytopenia not associated with a systemic disease, based on the history of drug ingestion or injection and laboratory findings.

[Generation and preliminary application of rabbit anti-human polyclonal antibodies against NH2-terminal peptides of CXCR3-B].

Aim: To generate and identify the rabbit polyclonal antibodies against NH(2)-terminal peptides of CXCR3-B.

Methods: Three peptides (aa. 1 to 19, aa.

Platelet factor 4 differentially modulates CD4+CD25+ (regulatory) versus CD4+CD25- (nonregulatory) T cells.

Active suppression mediated by CD4(+)CD25(+) T regulatory (Tr) cells plays an important role in the down-regulation of T cell responses to both foreign and self-Ags. Platelet factor 4 (PF4), a platelet-derived CXC chemokine, has been shown to strongly inhibit T cell proliferation as well as IFN-gamma and IL-2 release by isolated T cells. In this report we show that human PF4 stimulates proliferation of the naturally anergic human CD4(+)CD25(+) Tr cells while inhibiting proliferation of CD4(+)CD25(-) T cells.

Heparin-induced thrombocytopenia: molecular pathogenesis.

Heparin-induced thrombocytopenia (HIT) is a common and often serious complication of heparin therapy [1,2]. Although the reduction in platelet levels associated with HIT is usually not severe, about 10% of patients experience arterial and/or venous thromboses (HITT), which can be incapacitating or fatal [3]. Recent work done in our laboratory [4] and by others [5-7] has shown that patients with HIT/T* almost invariably have antibodies specific for complexes consisting of heparin and platelet factor 4 (PF4), a heparin-binding protein found normally in platelet alpha granules.

Disruption of the long-range GPIIIa Cys(5)-Cys(435) disulfide bond results in the production of constitutively active GPIIb-IIIa (alpha(IIb)beta(3)) integrin complexes.

The major platelet integrin alpha(IIb)beta(3), also known as the platelet glycoprotein (GP) IIb-IIIa complex, mediates platelet aggregation by serving as the receptor for fibrinogen and von Willebrand factor. In addition to its physiologic role, GPIIb-IIIa also bears a number of clinically important alloantigenic determinants. Previous studies have shown that disruption of the long-range Cys(5)-Cys(435) disulfide bond of the beta(3) subunit results in the production of isoforms that bind some, but not all, anti-Pl(A1) alloantibodies, suggesting that mutations in this so-called long-range disulfide bond can alter the conformation of GPIIIa.