The Bruton tyrosine kinase inhibitor PCI-32765 ameliorates autoimmune arthritis by inhibition of multiple effector cells

Table 1 Effect of PCI-32765 on monocytes, macrophages and mast cells

Cell type	Stimulation	EC ₅₀ in nM (peak concentration, pg/mL)
		TNFα	IL-6	IL-1β	MCP-1	IL-8	Histamine	PGD2
THP-1	FcγR LPS	0.9 (577) > 10,000 (934)	ND > 10,000 (638)	5.2 (80) ND	ND ND
Primary human monocytes	FcγR LPS	2.6 (6854) > 10,000 (2100)	3.9 (1380) > 10,000 (528)	0.5 (100) ND	908 (3593) ND
Primary human macrophages Primary mouse macrophages	FcγR FcγR	561 (337) 4.9 (126)	1299 (1500) 0.9 (404)	26.6 (132) 5.1 (22)	422 (1451) 183 (676)
RAW 267.4 Primary human macrophages	FcγR (cFb) FcγR (cFb)	8.7 (619) 113 (1350)	ND ND	ND ND	ND ND
Human cultured mast cells	FcεR FcγR	61 (236) 2.1 (67)	ND ND	ND ND	2.2 (341) ND	32 (722) 7.7 (263)	25 (460) 24 (238)	21 (1573) 14 (575)
* ng/mL

PCI-32765 inhibits FcγR-stimulated production of TNFα, IL-6, IL-1β, and MCP-1 in THP-1 cells, human primary monocytes, human macrophages, and mouse macrophages. PCI-32765 inhibits human mast cell releases of histamine, PGD₂, TNFα, IL-8, and MCP-1 following activations of FcεR and FcγR pathways. THP-1, primary monocytes, and monocyte-derived macrophages were stimulated with high concentration of plate-bound human IgG (or mouse IgG in case of mouse macrophages). RAW 267.4 cells and human macrophages were stimulated with plate-bound citrullinated fibrinogen immune-complexes (ICs) as described in Supplemental Methods [see Additional file 3]. Monocytes and macrophages were pre-treated with PCI-32765 for 30 minutes, and mast cells were treated for 10 minutes prior to stimulations. Mast cells were stimulated with anti-IgE or aggregated IgG₁. The citrullinated fibrinogen IC experiments were performed twice in triplicates. All other experiments were performed three to five times in triplicate with similar results, and the average IC₅₀ of two to three representative experiments is shown. Peak concentrations of readout cytokines/factors are in parenthesis. ND, no data.