A Macromolecular Serum Component Acting on Platelets in the Presence of EDTA —‘Platelet Stain Preventing Factor’

A macromolecular serum component, platelet stain preventing factor (PSPF), possessing the capacity to prevent staining of platelets, has been observed in the serum of an apparently healthy person. The factor is active only when EDTA is present, and it has reacted with all platelet samples tested until now. Thus far, it has not been possible to demonstrate that the factor resides in any of the known serum proteins.     

A Case of Variant Congenital Dyserythropoietic Anemia Revisited

A patient with congenital dysterythropoietic anemia was described in 1975 as variant type II because of negative acidified lysis tests using 12 different fresh sera. Subsequent tests with 2 additional normal sera have been strongly positive.     

Flaming Promyelocytes in Acute Hypergranular Promyelocytic Leukaemia Light and Electron Microscopic Study

Flaming in the peripheral parts of promyelocytes was seen in 3 out of 4 patients with acute hypergranular promyelocytic leukaemia. In one of these patients (ER) the flaming was quite marked, and electron microscopy showed the flaming to correspond to greatly dilated cisternae of the RER.     

Human Leukaemia Associated Antigen (LAA):

Serum leukaemia-associated antigen (LAA) is identified as an oncofetal antigen (or antigens) since it is present in fetal liver and in amniotic fluid. Although it is mainly found in patients with proliferative haematological disorders, particularly acute leukaemias and chronic myelogenous leukaemia, LAA is occasionally present in sera from healthy people. In protein fractionation experiments, LAA behaves as a distinct population of molecules and has the characteristics of an α₂-β-globulin, not carrying any lipids. The origin of LAA in haematological disorders is unknown. Its presence does not correlate with high white blood cell count, although antibody to LAA has been raised in animals injected with blast cells from leukaemia patients. LAA is distinct from α-fetoprotein, and we have observed a reaction of immunolog-ical non-identity between LAA and ferritin. This is of considerable interest since ferritin has been reported to be immunologically closely related to α₂H-globulin which may occur in the same categories of patients as LAA. It is preliminary concluded that LAA as defined by our antisera may be different from α₂H-globulin and ferritin.     

Natural cytotoxicity in adult acute leukemia

Natural cytotoxic activity was studied in 32 adult patients with acute non-lymphoid leukemia (ANLL) and 27 adult patients with acute lymphoblastic leukemia (ALL). Thirteen patients with active ANLL had a significantly reduced natural cytotoxicity in peripheral blood compared with that of healthy controls, 5.0 +/- 3.4 versus 27.1 +/- 11.5 (p less than 0.0005). Patients with ANLL in remission had a normal natural cytotoxicity (p greater than 0.05). Patients with active ANLL had a significantly reduced number of Leu-7-positive cells (p less than 0.001), while patients in remission had normal proportions of these cells (p greater than 0.05). Peripheral blood from patients with ALL showed reduced natural killer (NK) cell activity, both in active disease and in remission (p less than 0.0005). The percentage of Leu-11b (CD 16)-positive cells was increased in patients in remission from ALL (p less than 0.05). Bone marrow cells from patients with ALL in remission had a reduced natural cytotoxicity, 2.8 +/- 4.0 versus 16.3 +/- 9.0 in bone marrow controls (p = 0.01). In contrast, patients with ANLL in remission showed a normal bone marrow cytotoxicity (p greater than 0.05) while patients with active ANLL had a reduced NK cell activity (p less than 0.03). The low NK activity observed in leukemic patients may be of importance for the pathogenesis of the diseases. Acute non-lymphoid leukemia (ANLL) is a malignant disease of the multipotential hemapoietic stem cell. The stem cell is capable of differentiating into various cell lineages, i.e. erythroid, granulocytic, monocytic and megacariocytic cell lineages.(ABSTRACT TRUNCATED AT 250 WORDS)