DETECTION OF ALLO AND AUTO ANTI-PLATELET ANTIBODIES BY FLOW CYTOMETORY : Ⅱ. MEASUREMENT OF ANTI-PLATELET ANTIBODIES OF SERA IN PATIENTS WITH IDIOPATHIC THROMBOCYTOPENIC PURPURA AND SYSTEMIC LUPUS ERYTHEMATOSUS

In a previous paper, I have shown evidence that acid treatment of washed normal platelets followed by formalin-fixation serves as a suitable material to detect auto and allo antibodies to platelets by flow cytometry. The percentage of fluorescence positive cells (% FPC) was less than 20.0 for fifty healthy adults. In this paper, I determined the levels of platelet bound IgG (PBIgG) in 20 patients with chronic ITP and in 27 patients with SLE. The % FPC in chronic ITP ranged from 97.1 to 8.3 (44.7±29.4, mean±SD), and that for SLE from 99.5 to 9.3 (38.8±23.9, mean±SD). In the patients with chronic ITP, a clearly inverted correlation was observed between platelet count and % FPCs (r=-0.6511, p＜0.01). Next, the captured enzyme liked sorbent assay (ELISA) and the immunoblotting assay were performed on these serum specimens. In captured ELISA, anti GPⅠb or Ⅱb/Ⅲa complex, mouse monoclonal antibodies designed by Ⅰbl and CP8 (provided by Dr. Zimmerman at Scripps Clinics), were used as the solid phase antibody to micro plate and 1% Triton X-100 soluble fraction of platelet lysate was used for epitope antigen to these MoAbs. Allo antibodies bound to respective antigens were detected ALP conjugated anti mouse IgG. By this procedure, in seven of 20 patients with chronic ITP and 4 out of 27 patients with SLE anti GPⅠb antibody were detected. Similarly, in two patients with chronic ITP and in 4 patients with SLE, anti GPⅡb/Ⅲa complex antibody were detected. Of these patients, only one patient with SLE had specific antibody against 45Kd fraction of platelet lysate which was shown by immunoblotting assay