Granulocytic progenitor cells in aplastic anaemia

The characteristics and the concentration of granulopoietic colony forming cells (CFC) were examined in 22 patients with aplastic anaemia at different stages of their disease. Additionally the ability of the patients' peripheral leucocytes to elaborate factors necessary for colony stimulation in vitro (CSA) was studied. The ability of the patients' cells to generate CSA was shown to be unaffected. However, the incidence of CFC within the marrow and peripheral blood suspensions was significanlty reduced in all patients. The results suggest a reduced compartment size of CFC even in those patients who have recovered from aplastic anaemia. This may indicate that the disturbances in the preceding compartments of the haemopoietic cell renewal system still persist after recovery from the acute bone marrow failure.

The role of granulocytes in colony stimulation by human white blood cells in agar cultures. Enhancement and inhibition of CSA

The effect of polymorphonuclear granulocytes (PMN) on colony stimulating activity (CSA) was studied in double layer cultures of human Ficoll Isopaque separated white blood cells (mononuclear cells = MNC). Previously published data have been confirmed that granulocytes are able to enhance or inhibit MNC derived CSA. Further analysis of the mode of action of PMN in vitro indicates that the enhancing activity ascribed to granulocytes coincides with low CSA in MNC basal layers. In contrast, in cultures with high levels of CSA as provided by lysed red blood cell enhancement rather than concentrations of PMN are sufficient to induce inhibition of colony growth. A very similar effect to that achieved with basal layer derived CSA could be obtained with conditioned media of PMN and MNC short term liquid cultures. The data indicate, that enhancement and inhibition of colony growth reflect a specific reactivity of granulocytes (PMN) to a given CSA level in the cultures. These findings are discussed in terms of a speculative role of PMN in a negative feed back control mechanism regulating granulopoiesis in vivo.

Identification of high-risk patients with aplastic anaemia in selection for allogeneic 0one-marrow transplantation

Of 75 patients with asplastic anaemia treated between 1968 and 1975, 33 were retrospectively considered as potential candidates for allogenegic bone-marrow transplantation on the basis of their age and severity of marrow failure. The prognosis of these patients with conservative treatment was assessed from parameters obtained at the time of the initial diagnosis. Initial peripheral-blood granulocyte or platelet concentrations were not of porgnostic value. In contrast, initial reticulocyte concentrations, allowed separation of the patients into two groups with poor and good prognosis. Low initial reticulocyte concentrations (less than 10 000/mu1) indicated those patients at extremely high risk of succumbing to their marrow aplasia (there were no survivors 36 months after disgnosis). In contrast, 75% of those patients with more than 10 000 reticulocytes per mu1 at diagnosis survived for 3 years. Initial peripheral-blood reticulocyte concentrations thus appear to indicate the extent of the marrow failure in aplastic anaemia more accurately than granulocytes or platelets. Low initial reticulocyte concentrations may indicate, among patients with severe aplastic anaemia, those for whom allogeneic bone-marrow transplantation should be seriously considered; patients with higher initial reticulocyte concentrations may benefit from conservation treatment.

Biochemical and ultrastructural study of human diabetic conjunctiva

Combined biochemical and ultrastructural study of conjunctival biopsies of 27 normal subjects and 45 diabetics (40 to 60 years old) was made. The "in vitro" incorporation of 14C-glucosamine and 3H-proline in freshly excised conjunctival biopsies was studied. The alterations of the capillary basement membrane of the conjunctiva were studied by electron microscopy. The following results were obtained: 1) A decrease of the specific activity of 14C-glucosmaine incorporation was found in fractions of diabetic conjunctiva. 2) In diabetic conjunctiva the percentages of 3H-proline incorporation in polymeric collagen containing fraction and structural glycoproteins containing fraction were significantly increased with a parallel decrease of 3H-proline incorporation in "crude soluble collagen" fraction expressed as a percentage of total incorporation. 3) Significant thickening of capillary basement membrane was observed with the appearance of collagen-like fibrils within the basement membrane in diabetic conjunctiva. Such fibrils were not seen in normal basement membranes. A relation between the extent of basement membrane thickening and the appearance of collagen-like fibrils is suggested. 4) The higher percentage of incorporation of 3H-proline in polymeric collagen may be related to the appearance of collagen fibrils in thickened basement membranes of the diabetic conjunctival capillaries. 5) These results suggest an abnormal regulation of the relative rate of biosynthesis and/or excretion of intercellular matrix macromolecules (collagen, structural glycoproteins) as part of the metabolic disorders characterising diabetes.

Decreased binding of insulin to liver plasma membrane receptors in hereditary diabetic mice

The interaction of insulin with its receptors was studied in liver plasma membranes of the young non-obese hereditary diabetic mouse (KK strain). Under identical conditions of preparation and incubation, the membranes of the KK mouse bind only 55-70% as much insulin per mg of protein as those of the control mouse (Swiss albino). Scatchard analysis suggests that this decrease in binding is due to a decrease in the number of receptor sites in the membrane of the diabetic mouse. However, the membranes of diabetic and control mice do not exhibit significant differences in hexosamine and sialic acid contents, enzyme activities, and protein and glycoprotein analysis. The decrease in insulin receptors in the KK mouse seems to correlate with the insulin resistance which they exhibit.