The impact of spleen tyrosine kinase (Syk) signaling might be prominent in lupus because (i) Syk is a shared downstream signaling molecule among circulating immune complex, LPS, and (1→3)-β-D-glucan (BG), and (ii) all of these factors are detectable in the serum of Fc gamma receptor IIb-deficient (FcgRIIb-/-) mice with sepsis. Syk inhibition downregulated several inflammatory pathways in FcgRIIb-/- macrophages activated with BG + LPS suggesting the potential anti-inflammatory impact of Syk inhibitors in lupus.

Homocystine is the double-bonded form of homocysteine but it occurs only transiently before being converted to the harmless cystathionine via a vitamin B6-dependent enzyme. Homocystine and homocysteine-cysteine mixed disulfide account for >98% of total homocysteine in plasma from healthy individuals.

L-Buthionine-(SR)-sulfoximine is a cell-permeable and irreversible inhibitor of γ-glutamylcysteine synthetase (Ki <100 μM) that induces oxidative stress in cells by depleting GSH.