Protein A

Protein A (1 μM; 2 h) activates the human mantle cell VH3⁺ B-cell lymphoma MAVER-1 cells, increasing the CD69 expression level to 31.6% after 2 h of treatment, while the addition of fetal bovine serum inhibits this activation effect^[1].
Protein A (1 μM; 5 min-16 h) exerts rapid toxicity on purified primary human B cells in medium supplemented with 10% human serum, causing an average 38% cell loss over incubation periods ranging from 5 min to 16 h^[1].
Incubation of Protein A (1 μM; 5 min-2 h) with intact human IgG induces ≥90% cytotoxicity in the human mantle cell VH3⁺ B-cell lymphoma MAVER-1 cells, triggering rapid necrosis (90% of cells undergo necrosis within 5 min). This cytotoxicity is inhibited by immune sera from mice immunized with a non-binding SpA mutant^[1].
At a concentration of 1 μM for 16 h in medium supplemented with 10% human serum, Protein A induces a 40% reduction in the total number of primary human leukocytes, including significant toxicity to CD19⁺ B cells and HLA-DR⁺ CD14⁺ monocytes, but exhibits no toxicity to HLA-DR⁺ CD14⁻ dendritic cells^[1].
Protein A reduces the phagocytic activity of phagocytes against *Staphylococcus aureus* via antibody chelation mediated by the Fc region, induces B cell apoptosis by binding to the B cell receptor through the Fab region, and eliminates the B cell population that produces *Staphylococcus aureus*-specific antibodies^[2].

MedChemExpress (MCE) has not independently confirmed the accuracy of these methods. They are for reference only.