Table 5.
Correlation between GPIIIa PlA1/A2 genotype and S. aureus-induced platelet aggregation, activation and S. aureus–platelet binding using blood from selected healthy volunteers.
| Agonist | GPIIIa PlA1/A2 genotype |
P valuea | ||
|---|---|---|---|---|
| A1/A1 | A1/A2 | A2/A2 | ||
| Platelet-rich plasma (n = 88) | ||||
| Lag time, min | ||||
| Newman, stationary | 1.92 ± 0.65 | 1.83 ± 0.47 | 2.63 ± 1.25 | 0.965 |
| 209, stationary | 8.60 ± 3.51 | 12.44 ± 7.28 | 6.08 ± 1.41 | 0.862 |
| Newman, exponential | 6.07 ± 1.41 | 6.60 ± 1.26 | 6.92 ± 1.03 | 0.038 |
| 207, exponential | 9.19 ± 3.36 | 9.11 ± 3.62 | 8.31 ± 5.14 | 0.642 |
| 209, exponential | 1.94 ± 0.64 | 1.84 ± 0.50 | 3.13 ± 1.82 | 0.768 |
| Platelet aggregation, % | ||||
| Newman, stationary | 67 ± 10 | 69 ± 7 | 66 ± 2 | 0.809 |
| 209, stationary | 68 ± 8 | 64 ± 10 | 63 ± 33 | 0.033 |
| Newman, exponential | 69 ± 12 | 60 ± 19 | 76 ± 7 | 0.091 |
| 207, exponential | 66 ± 15 | 66 ± 13 | 70 ± 16 | 0.595 |
| 209, exponential | 63 ± 9 | 63 ± 14 | 67 ± 4 | 0.642 |
| ADP | 69 ± 12 | 74 ± 12 | 70 ± 6 | 0.074 |
| SFLLRN–NH2 | 68 ± 12 | 69 ± 13 | 69 ± 7 | 0.762 |
| Washed platelets (n = 31) | ||||
| Lag time, min | ||||
| Newman, stationary | 3.00 ± 0.90 | 2.89 ± 1.26 | 9.21 ± 10.56 | 0.553 |
| 209, stationary | 10.20 ± 8.73 | 9.10 ± 9.18 | 13.66 ± 7.88 | 0.418 |
| Newman, exponential | 8.65 ± 8.02 | 9.05 ± 9.16 | 21.01 ± 7.99b | 0.829 |
| 207, exponential | 25c | 19.24 ± 8.78 | 22.93 ± 4.14b | N/Ad |
| 209, exponential | 7.74 ± 5.48 | 8.74 ± 7.43 | 16.32 ± 10.10 | 0.979 |
| Platelet aggregation, % | ||||
| Newman, stationary | 82 ± 4 | 80 ± 6 | 78 ± 5 | 0.590 |
| 209, stationary | 73 ± 12 | 77 ± 7 | 73 ± 17 | 0.692 |
| Newman, exponential | 66 ± 16 | 75 ± 6 | 78b | 0.314 |
| 209, exponential | 71 ± 12 | 72 ± 8 | 75 ± 1 | 0.830 |
| ADP | 29 ± 20 | 36 ± 17 | 12 ± 16 | 0.215 |
| SFLLRN–NH2 | 71 ± 19 | 75 ± 5 | 64 ± 22 | 0.306 |
| Agonist-induced platelet activation, % (n = 31) | ||||
| Newman, stationary | 55 ± 29 | 49 ± 25 | 43 ± 33 | 0.711 |
| 209, stationary | 26 ± 11 | 18 ± 11 | 24 ± 6 | 0.093 |
| Newman, exponential | 36 ± 20 | 40 ± 19 | 31 ± 16 | 0.604 |
| 207, exponential | 24 ± 15 | 18 ± 12 | 25 ± 11 | 0.443 |
| 209, exponential | 28 ± 17 | 20 ± 12 | 21 ± 4 | 0.223 |
| SFLLRN–NH2 | 82 ± 14 | 83 ± 6 | 78 ± 14 | 0.660 |
| Percentage of platelets bound to S. aureus, % (n = 31) | ||||
| Newman, stationary | 84 ± 21 | 85 ± 26 | 91 ± 8 | 0.792 |
| 209, stationary | 86 ± 22 | 86 ± 23 | 92 ± 8 | 0.874 |
| Newman, exponential | 58 ± 27 | 53 ± 26 | 70 ± 31 | 0.751 |
| 207, exponential | 78 ± 25 | 74 ± 28 | 77 ± 20 | 0.426 |
| 209, exponential | 57 ± 25 | 52 ± 28 | 58 ± 19 | 0.598 |
| Percentage of S. aureus cells bound to platelets, % (n = 31) | ||||
| Newman, stationary | 49 ± 10 | 44 ± 15 | 56 ± 9 | 0.312 |
| 209, stationary | 44 ± 12 | 38 ± 12 | 48 ± 12 | 0.200 |
| Newman, exponential | 22 ± 12 | 18 ± 11 | 25 ± 8 | 0.711 |
| 207, exponential | 24 ± 10 | 21 ± 8 | 23 ± 3 | 0.339 |
| 209, exponential | 18 ± 11 | 14 ± 7 | 17 ± 3 | 0.419 |
Percentage platelet aggregation in response to strain 207 grown to exponential phase could not be analyzed when using washed platelets, as aggregation was only observed with platelets isolated from 2 subjects. Data for S. aureus strain 207 at stationary phase of growth were not analyzed as platelet aggregation was not observed in response to this agonist.
P values were determined using the Mann–Whitney U test comparing the PlA1/A1 to the PlA1/A2 genotype.
Only one PlA2/A2 subject’s washed platelets aggregated in response to S. aureus strains Newman and 207 at the exponential phase of growth.
Lag times of 25 min represent absence of platelet aggregation.
Statistical analyses could not be performed as platelet aggregation was not observed with PlA1/A1 platelets in response to strain 207 at the exponential phase of growth.