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In a Canadian family of northern Irish origin, a new hemoglobin variant, hemoglobin Etobicoke, was observed. It differs from hemoglobin A by having a residue of arginine in place of serine in position 84 of the α-chain (helical notation F5). This hemoglobin is slightly less stable than hemoglobin A, but it does not cause an inclusion body anemia.

Summary. In one type of hereditary dyserythropoietic anaemia, HEMPAS (hereditary erythroblastic multinuclearity with a positive acidified-serum test) striking increases in the activity of some, but not all, erythrocyte enzymes have been detected in three cases. Since there was only minimal reticulocytosis, these enzyme changes cannot be accounted for by the presence of a young erythrocyte population. It is suggested that the enzymatic abnormalities of HEMPAS result from abnormal karyo- and cyto-kinesis of the erythroid precursors.

A soluble glycosyltransferase which can trasfer N-acetylgalactosamine from UDP-N-acetylgalactosamine to exogenous acceptors is present in the serum of human subjects with the blood group A gene. The enzyme is in the serum of secretors and non-secretors of group A and AB but is not in the serum of group 0 or B subjects. The activity of serum from A 1 subjects is 5 to 10 times higher than that from A 2 subjects. Activity was lower in two group A 1 pregnant women. There was low activity in the serum of a hematopoietic chimera whose A 1 gene is restricted to her “grafted” blood cells.

SUMMARY Hyperacute rejection of cardiac allografts was studied in dogs sensitized by two previous heart, kidney, or skin grafts or more. Organ donors were selected on the basis of a positive cytotoxicity test using the donor's lymphocytes and the recipient's serum. Eight of the 19 heart grafts were rejected in less than 4 hr; 7 of the 8 were rejected in less than 1 hr. Characteristic gross changes included cyanosis and turgor. Serial biopsies of myocardium within the first 1/2 hr showed interstitial edema and hemorrhage, but no infiltration with inflammatory cells. Small arterioles and capillaries were occluded by clumps of platelets. In most hearts, immunofluorescence staining revealed IgG in the walls of blood vessels and on the sarcolemma. Bound complement (β10-globulin) was seldom detected. There was some correlation between the occurrence of hyperacute rejection and the titer of cytotoxic antibody in the recipient's serum against the donor's lymphocytes. It is suggested that antibody-antigen complexes formed in the graft cause platelet aggregation with occlusion of the lumen and damage to the walls of small blood vessels.

Blood chimaerism in twins of unlike sex was established by karyotypes and by differences in five genetic marker systems. The female twin produced an unusual antibody (anti-A 1 Le b ) which agglutinated the A 1 red blood-cells in the male twin's blood. This apparent breakdown of immune tolerance could be explained by the postnatal development of Lewis substances, and the consequent lack of molecules with A 1 Le b specificity in the plasma of the group-A fetal blood grafted from the male to the female twin in utero. This graft contained only blood-cells, and not secretory cells: thus, although 50% of the female twin's red blood-cells were A 1 ,Le(b+), she could not secrete A and A 1 Le b substances into her body fluids. Transformation experiments, in vitro and in vivo, supported the new hypothesis that the plasma of A 1 ,Le(b+) subjects normally contains A 1 Le b molecules.

The level of blood-group A1-specified alpha,3'-N-acetyl-D-galactosaminyl-transferase in the serum of recently-delivered women was found to be appreciably lower than the level of this enzyme in the serum of non-pregnant adults and of newborn infants; a similar but less striking decrease was observed in the levels of the A2-specified alpha,3'-N-acetyl-D-galactosaminyltransferase and the H-specified alpha,2'-L-fucosyltransferase. Although the red cells of newborn infants are known to have relatively few A and H antigen sites, the serum of neonates was found to have a level of A1- and A2-dependent N-acetylgalactosaminyltransferases and H-dependent fucosyltransferase as high as, if not higher than, the serum of non-pregnant adults. This finding is compatible with the fact that the haemopoietic tissue contributes only about 20% of the serum transferase level.

Summary. In five patients (including two sisters) an unusual anaemia was characterized by erythroblastic multinuclearity, ineffective erythropoiesis and a positive acidified-serum test. Unlike PNH, the sugar-water test was always negative in these patients. The lysis of their cells by acidified normal sera indicated their abnormal sensitivity to an agglutinating and complement-binding antibody present in some normal subjects. The patients cells gave high agglutination scores with anti-i, and were unusually susceptible to lysis by anti-i and anti-I. The disorder is apparently inherited as an autosomal recessive character.