Study on the pathogenesis of acquired pure amegakaryocytic thrombocytopenic purpura

Objective: To investigate the possible pathogenesis of acquired pure amegakaryocytic thrombocytopenic purpura(APATP).

Methods: Twenty eight patients with APATP were studied. Bone marrow mononuclear cells(MNCs) from these patients were plated into methyl cellulose cultures for CFU-GM, CFU-E and CFU-MK assay. The influence of depleting T cells or adherent cells from patients' marrow cells on CFU-MK growth was observed. The humoral inhibitory effect on CFU-MK was determined by co-incubation of patients' sera or IgG with normal or autologous MNCs prior to cultures. The serum MK-CSA was also assessed.

Results: Fifteen cases (53.6%) of APATP was resulted from intrinsic defect of CFU-MK. The megakaryocyte colony formation was augmented significantly in 3 T lymphocytes-depleted and 2 mono-macrophages depleted patients. Sera from 6 patients(21.4%) were inhibitor to CFU-MK. The inhibitor originated from IgG and selectively directed against the megakaryocyte. In the remaining 2 cases, the pathogenesis was not ascertained.

Conclusions: The intrinsic defect of megakaryocyte progenitor cell is considered to be a primary pathogenesis of APATP. In some patients the disease can result from abnormal immune mechanisms. The decompensation of MK-CSA production could also be an important cause for APATP.