Thrombocytopenia in patients with severe acute respiratory syndrome (review).

Severe Acute Respiratory Syndrome (SARS) has been recognized as a new human infectious disease caused by a novel coronavirus (SARS-CoV). Hematological changes in patients with SARS were common, including notably lymphopenia and thrombocytopenia. While the former is the result of decreases in CD4+ or CD8+ T-lymphocytes related to the onset of disease or use of glucocorticoids, the latter may involve a number of potential mechanisms. Although the development of autoimmune antibodies or immune complexes triggered by viral infection may play a significant role in inducing thrombocytopenia, SARS-CoV may also directly infect hematopoietic stem/progenitor cells, megakaryocytes and platelets inducing their growth inhibition and apoptosis. Moreover, the increased consumption of platelets and/or the decreased production of platelets in the damaged lungs are a potential alternative mechanism that can contribute to thrombocytopenia in severe critical pulmonary conditions, which has been rarely revealed and will be discussed.