SPLENIC CLEARANCE MECHANISMS OF REHYDRATED, LYOPHILIZED PLATELETS

Figures & data

Table 1. Mechanisms for Retention and Phagocytosis in the Spleen

Mechanism	MAC and EC Receptor	Ligand	Inhibition
Fc receptor mediated	FC receptor	IgG bound to neocryptic-senescence antigens on RL platelet	IV IgG
Complement mediated	Complement receptor 1 (CR1)	Ig bound C4b, C4b, iC3b	soluble CR1 anti-C3 and C5 antibody
	Complement receptor 3 (CR3)	Lipopolysaccharide NPC 15669
Lectin-like receptor mediated	Mannose receptor galactose receptor MAC-2 CD14	Altered or cryptic carbohydrates	mannan, mannose lactose galactose muramyldipeptide
Scavenger receptor mediated	Type I, type II and MARCO scavenger receptors	Altered carbohydrates, oxidized/modified lipoproteins, surface phosphatidyl-serine	Inhibit with polyanions Inhibit with annexin and PS
Chemokine mediated	Chemokine receptor CCR2 DCAR receptor	Chemokine release by platelets	anti-MPL-2 antibody MPL-2 peptidaminics
Epinephrine sensitive marginalization	Selectins, CAMs Physical entrapment in splenic sinus	Selectins, CAMs, fibrinogen, vWF	Epinephrine alpha-adrenergic agonists

Figure 1. Circulation kinetics of RL platelets with and without (Gd treated) RES macrophages.

Figure 2. Fluorescence microscopy of RL platelets in slenic sinus.

Figure 3. In vitro microphage phagocytosis of RL platelets.

Figure 4. IV IgG prolongs circulation.

Figure 5. Anti-RL platelet IgG is pre-existing in the circulation. 1. RL platelets bind approximately three times more IgG than fresh platelets when incubated with pre-infusion serum. 2. The amount of IgG that binds to each RL platelet is heterodispersed. Flow Cytometric Histograms from Dog X14 Serum incubated with RL or Fresh Platelets.