Figure 1
Figure 1. Anti-PF4/heparin antibodies (by EIA) per postoperative day in 12 patients with HIT and 36 seropositive non-HIT control patients. (A) Mean (±SEM) optical density (OD) of anti-PF4/heparin antibodies detected using commercial immunoassay (EIA-GTI) that detects antibodies of all 3 immunoglobulin classes (IgG, IgA, IgM). HIT patients are indicated by ■, and seropositive non-HIT controls by □. On each day beginning on postoperative day 6, there is a significant difference in the mean of the OD levels between the patients with HIT and the seropositive non-HIT controls (P < .05 by nonpaired t test). At the top of the figure, summary data for 12 HIT patient profiles are shown for 4 key events (first day of antibody detection, beginning of HIT-related platelet count fall, platelet count fall ≥ 50%, and thrombotic event), summarized as median (small black squares within rectangles), IQR (open rectangles), and range (ends of thin black lines). (B) Mean (±SEM) OD values of anti-PF4/heparin antibodies detected using an in-house immunoassay (EIA-Ig) that detects antibodies of the individual immunoglobulin classes, IgG (red circles), IgA (green triangles), and IgM (blue inverted triangles) for HIT (solid symbols) and non-HIT (open symbols). On each postoperative day beginning on day 5, there is a significant difference in the mean of the OD units for the IgG immunoassay between the patients with HIT and the seropositive non-HIT controls (**P < .005 for days 6-10; *P < .05 for days 5, 11, and 12). In addition, among the 34 non-HIT controls who tested positive for IgG antibodies, mean (±SEM) maximum OD values for the EIA-IgG were significantly greater in the 8 patients who tested positive in the serotonin-release assay compared with the 26 patients who tested negative in the serotonin-release assay (1.30 ± 0.15 vs 0.96 ± 0.07 units; P = .025). Among the 20 patients who tested positive in the serotonin-release assay, mean (±SEM) maximum OD values for the EIA-IgG showed a trend to higher levels in the 12 patients with clinical HIT, compared with the 8 seropositive non-HIT controls (1.63 ± 0.09 vs 1.30 ± 0.15 units; P = .059). EIA indicates enzyme immunoassay; and HIT, heparin-induced thrombocytopenia.

Anti-PF4/heparin antibodies (by EIA) per postoperative day in 12 patients with HIT and 36 seropositive non-HIT control patients. (A) Mean (±SEM) optical density (OD) of anti-PF4/heparin antibodies detected using commercial immunoassay (EIA-GTI) that detects antibodies of all 3 immunoglobulin classes (IgG, IgA, IgM). HIT patients are indicated by ■, and seropositive non-HIT controls by □. On each day beginning on postoperative day 6, there is a significant difference in the mean of the OD levels between the patients with HIT and the seropositive non-HIT controls (P < .05 by nonpaired t test). At the top of the figure, summary data for 12 HIT patient profiles are shown for 4 key events (first day of antibody detection, beginning of HIT-related platelet count fall, platelet count fall ≥ 50%, and thrombotic event), summarized as median (small black squares within rectangles), IQR (open rectangles), and range (ends of thin black lines). (B) Mean (±SEM) OD values of anti-PF4/heparin antibodies detected using an in-house immunoassay (EIA-Ig) that detects antibodies of the individual immunoglobulin classes, IgG (red circles), IgA (green triangles), and IgM (blue inverted triangles) for HIT (solid symbols) and non-HIT (open symbols). On each postoperative day beginning on day 5, there is a significant difference in the mean of the OD units for the IgG immunoassay between the patients with HIT and the seropositive non-HIT controls (**P < .005 for days 6-10; *P < .05 for days 5, 11, and 12). In addition, among the 34 non-HIT controls who tested positive for IgG antibodies, mean (±SEM) maximum OD values for the EIA-IgG were significantly greater in the 8 patients who tested positive in the serotonin-release assay compared with the 26 patients who tested negative in the serotonin-release assay (1.30 ± 0.15 vs 0.96 ± 0.07 units; P = .025). Among the 20 patients who tested positive in the serotonin-release assay, mean (±SEM) maximum OD values for the EIA-IgG showed a trend to higher levels in the 12 patients with clinical HIT, compared with the 8 seropositive non-HIT controls (1.63 ± 0.09 vs 1.30 ± 0.15 units; P = .059). EIA indicates enzyme immunoassay; and HIT, heparin-induced thrombocytopenia.

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