Platelet function and structure in myeloproliferative disease, myelodysplastic syndrome, and secondary thrombocytosis.

Platelet function and morphologic characteristics were evaluated in 43 patients with myeloproliferative disease (MPD), 5 patients with myelodysplastic syndrome (MDS), and 7 patients with secondary thrombocytosis (ST). Platelet Factor IV (PF4) and B-thromboglobulin (BTG) showed slight elevation in ST but significant elevation in all MPDs. They were either normal or slightly elevated in MDS. Defective platelet aggregation with one or more inducers was seen in 62% of all patients. An epinephrine-induced defect was the most consistent aggregation abnormality. Hyperaggregation and spontaneous aggregation were seen in 15% of patients. Of the eight patients who showed increased bleeding tendency, all eight showed defective aggregation with two or more inducers, five showed decreased surface activation response, as well as decreased or abnormal granules and dense tubular disarray in the transmission electron microscope (TEM) study. Seven patients had clinical evidence of recurrent arterial and venous thromboses. Five of these patients showed hyperaggregation response to adenosine diphosphate and collagen and abnormal Wu and Hoak platelet aggregate ratio. Four patients showed spontaneous aggregation on aggregometer. Surface activation response was significantly increased in five patients, and an increase in platelet granules by TEM study was seen in four patients. Primary thrombocythemia could be differentiated from secondary thrombocytosis (ST) by the presence of abnormal aggregation response and significantly increased PF4 and BTG in the former, and greatly elevated plasma fibrinogen and Factor VIII, as part of acute phase reactant response, in the latter.

Sheep erythrocyte rosette formation by B chronic lymphocytic leukemia cells as a consequence of monoclonal surface immunoglobulin with "Forssman-like" antibody activity.

Peripheral blood and splenic lymphocytes from an elderly man with chronic lymphocytic leukemia (Rai stage 4) were shown to have monoclonal surface immunoglobulin (IgM+, IgD+, kappa+), Ia-like antigen and receptors for unsensitized sheep red blood cells. The sheep red blood cell receptor was not blocked by monoclonal antibodies that bind to the classic T lymphocyte rosette receptor (OKT-11 and Lyt-3) or by anti-human IgG or antilambda antibodies. However, the sheep red blood cell receptor was blocked by antihuman IgM and kappa antisera and by soluble guinea pig kidney antigen (Forssman antigen). It is concluded from these and other observations that our patient has a B-cell lymphoproliferative disorder expressing monoclonal surface immunoglobulin with anti-"Forssman-like" antibody activity.