Table 1 Volunteer details,... | American Society of Hematology

Table 1

Volunteer details, radiolabeling, and sensitization combinations and individual platelet recovery and survival data using the COST program

UPN	Platelet count	HPA-1a expression levels, MFI	Radiolabel and antibody combination		Five-minute recovery, %		COST data
			Unsensitized	B2G1Δnab	Unsensitized	B2G1Δnab	Unsensitized		B2G1Δnab
			Unsensitized	B2G1Δnab	Unsensitized	B2G1Δnab	Recovery, %	Survival, h	Recovery, %	Survival, h
1	172	16.3	Cr⁵¹	¹¹¹In	66	94	48	83	73	98
2	270	15.8	¹¹¹In	Cr⁵¹	72	94	59	191	71	177
3	412	15.6	Cr⁵¹	¹¹¹In	47	36	36	151	30	283
4	260	18.2	Cr⁵¹	¹¹¹In	54	68	54	214	65	238
5	270	No data	¹¹¹In	Cr⁵¹	51	42	51	254	33	215
6	299	17.1	Cr⁵¹	¹¹¹In	38	61	32	212	57	216
7	324	16.9	¹¹¹In	Cr⁵¹	69	77	61	212	65	243
							Unsensitized		B2G1
			Unsensitized	B2G1	Unsensitized	B2G1	Recovery, %	Survival, h	Recovery, %	Survival, min
8	249	19.2	¹¹¹In	Cr⁵¹	93	53	62	198	38	14
9	311	14.3	Cr⁵¹	¹¹¹In	57	63	42	223	39	18
							Unsensitized		B2G1Δnab75*
			Unsensitized	B2G1Δnab75	Unsensitized	B2G1Δnab75	Recovery, %	Survival, h	Recovery, %	Survival, min
10	190	No data	Cr⁵¹	¹¹¹In	70	82	58	152	56	48
11	257	17.7	¹¹¹In	Cr⁵¹	70	75	60	219	43	40
12	230	18.2	¹¹¹In	Cr⁵¹	60	50	54	162	59	45
							B2G1		B2G1Δnab90*
			B2G1	B2G1Δnab90	B2G1	B2G1Δnab90	Recovery, %	Survival, min	Recovery, %	Survival, min
13	234	14.7	¹¹¹In	Cr⁵¹	95	83	70	28	50	45
14	238	15.2	Cr⁵¹	¹¹¹In	51	77	27	14	30	50
15	175	14.0	¹¹¹In	Cr⁵¹	65	60	63	15	44	77
16	239	18.0	¹¹¹In	Cr⁵¹	60	79	65	18	86	62
17	198	16.6	¹¹¹In	Cr⁵¹	78	79	36	17	61	56
18	276	26.3†	Cr⁵¹	¹¹¹In	57	69	81	19	96	25

UPN	Platelet count	HPA-1a expression levels, MFI	Radiolabel and antibody combination		Five-minute recovery, %		COST data
			Unsensitized	B2G1Δnab	Unsensitized	B2G1Δnab	Unsensitized		B2G1Δnab
			Unsensitized	B2G1Δnab	Unsensitized	B2G1Δnab	Recovery, %	Survival, h	Recovery, %	Survival, h
1	172	16.3	Cr⁵¹	¹¹¹In	66	94	48	83	73	98
2	270	15.8	¹¹¹In	Cr⁵¹	72	94	59	191	71	177
3	412	15.6	Cr⁵¹	¹¹¹In	47	36	36	151	30	283
4	260	18.2	Cr⁵¹	¹¹¹In	54	68	54	214	65	238
5	270	No data	¹¹¹In	Cr⁵¹	51	42	51	254	33	215
6	299	17.1	Cr⁵¹	¹¹¹In	38	61	32	212	57	216
7	324	16.9	¹¹¹In	Cr⁵¹	69	77	61	212	65	243
							Unsensitized		B2G1
			Unsensitized	B2G1	Unsensitized	B2G1	Recovery, %	Survival, h	Recovery, %	Survival, min
8	249	19.2	¹¹¹In	Cr⁵¹	93	53	62	198	38	14
9	311	14.3	Cr⁵¹	¹¹¹In	57	63	42	223	39	18
							Unsensitized		B2G1Δnab75*
			Unsensitized	B2G1Δnab75	Unsensitized	B2G1Δnab75	Recovery, %	Survival, h	Recovery, %	Survival, min
10	190	No data	Cr⁵¹	¹¹¹In	70	82	58	152	56	48
11	257	17.7	¹¹¹In	Cr⁵¹	70	75	60	219	43	40
12	230	18.2	¹¹¹In	Cr⁵¹	60	50	54	162	59	45
							B2G1		B2G1Δnab90*
			B2G1	B2G1Δnab90	B2G1	B2G1Δnab90	Recovery, %	Survival, min	Recovery, %	Survival, min
13	234	14.7	¹¹¹In	Cr⁵¹	95	83	70	28	50	45
14	238	15.2	Cr⁵¹	¹¹¹In	51	77	27	14	30	50
15	175	14.0	¹¹¹In	Cr⁵¹	65	60	63	15	44	77
16	239	18.0	¹¹¹In	Cr⁵¹	60	79	65	18	86	62
17	198	16.6	¹¹¹In	Cr⁵¹	78	79	36	17	61	56
18	276	26.3†	Cr⁵¹	¹¹¹In	57	69	81	19	96	25

The COST program is a mathematical tool that fits a theoretical survival curve to the measurements of platelet recovery at the various time points³² and infers platelet survival and recovery at time 0 from the fitted curve using the multiple hit calculation model. The first time point used for the curve fitting should be taken after equilibrium.^33,34 For unsensitized and B2G1Δnab-sensitized platelets which showed a plateau phase during the first 24 hours (see Figure 1), the 24-hour time point was used as the first point for the curve fit. For B2G1-sensitized platelets and platelets sensitized with a combination of 75% B2G1Δnab/25% B2G1 and 90% B2G1Δnab/10% B2G1B2G1Δnab 90%/ B2G1 10% (*B2G1Δnab75 and -90, respectively) where rapid destruction was observed without a plateau phase (see Figure 1), the 5-minute time point was used (see “Results”).

†

UPN 18 had a much higher HPA-1a expression level (MFI 26.3 vs mean ± SD MFI of 16.5 ± 1.6 for the rest of the volunteers), and platelet survival data were very different from other volunteers (see supplemental Figure 1). Data from this volunteer were therefore excluded from subsequent analysis.

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