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The Kell blood group is one of the major antigenic systems in human red blood cells. To determine the location of the Kell gene on human chromosomes, panels containing genomic DNA of human-hamster somatic cell hybrids were hybridized with radiolabeled cDNA probe specific for the Kell locus. Only the samples containing DNA from chromosome 7 gave positive hybridization signals. In situ hybridization analysis, using genomic clones isolated with the cDNA, localized the KEL gene to 7q33. Northern blot analysis of poly(A)+ RNA from human brain, kidney, lung, fetal and adult liver, and bone marrow showed that Kell transcripts were only present in fetal liver and bone marrow. This indicates that the Kell protein, which carries the Kell antigens, may only be expressed in erythroid tissues.

McLeod red cells (RBCs) lack Kx antigens and have weak expression of the Kell antigens. Individuals who carry the McLeod phenotype have acanthocytic RBCs and a compensated hemolytic state. To elucidate the role of the protein on which the Kx antigens reside in maintaining membrane deformability, the rheologic properties of McLeod RBCs were determined by ektacytometry. RBCs were obtained from normal individuals and from four patients with McLeod syndrome. Osmotic gradient deformability profiles of McLeod RBCs showed decreased whole cell deformability. Resealed ghosts from McLeod RBCs also showed decreased deformability, partly because of the decreased cell surface area and partly because of an intrinsic membrane stiffness in this syndrome. For the measurement of membrane mechanical stability, resealed ghosts were subjected to constant high shear stress in the ektacytomer, and deformability was recorded continuously as the deformable ghosts fragmented into rigid spherical vesicles. Membranes from McLeod RBCs showed a noticeable increase in mechanical stability. Acquired causes of acanthocytosis, such as liver disease, did not cause the rheologic abnormalities observed in McLeod cells. Other abnormalities noted in McLeod RBCs were decreased RBC potassium content and an increased number of dense RBCs, as determined by centrifugation on a discontinuous density gradient. The data indicate that McLeod RBCs are rigid and have decreased surface area and that their membranes are intrinsically rigid with increased mechanical stability. These abnormalities may account for the reduced RBC survival observed in McLeod syndrome. The protein that carries the Kx surface antigen seems to be required for the maintenance of the normal physical function of RBC skeletal proteins.

Red cells of the McLeod phenotype in the Kell blood group system have an acanthocytic morphology. The membrane protein composition analyzed on sodium dodecyl-sulfate-polyacrylamide gel electrophoresis, the ATP level and the activities of a large number of intracellular enzymes appear to be normal. Membranes prepared from McLeod red cells incubated with gamma AT[32P] and MgCl2 incorporated twice as much radioactivity into spectrin and also showed a slight elevation of phosphorylation in band 3 protein when compared to membranes from normal cells. Intact normal red cells incubated with carrier-free [32P] incorporated radioactivity into several proteins, with most incorporation in spectrin and band 3 protein. In comparison, McLeod cells incorporated three times more radioactivity into spectrin and band 3 protein but increased phosphorylation also occurred in other, but not all, membrane proteins. Intact McLeod red cells also showed increased phosphorylation of membrane phospholipids, but they incorporated [32P] into intracellular nucleotide phosphates in a normal manner.

A patient with Hodgkin's disease became temporarily Wj-negative with alloanti-Wj in his serum. Four human autoantibodies, and 1 of 2 murine monoclonal antibodies, with serological characteristics of anti-Wj were nonreactive with his red cells, confirming that they have anti-Wj specificity. Six siblings of the patient are all Wj-positive. The patient was also temporarily Anton-negative, and cross-testing between Wj and Anton red cells and antisera showed mutual compatibility, indicating that the antigens are the same. The patient and 3 of his 6 siblings are also of the rare Lu: - 13 phenotype, providing the first evidence that this is an inherited characteristic.

Since the early 1970s, measurement of free erythrocyte protoporphyrin (FEP) (by microextraction or by hematofluorometer) has been widely used to screen for lead poisoning and to evaluate microcytic red blood cell (RBC) disorders in children. However, published information on normal values for FEP, performance of the hematofluorometer, and usefulness of FEP in classifying microcytic RBC disorders in adults is scant. In an adult population with normal hematocrit and MCV and normal values for serum ferritin, blood lead level, and serum bilirubin, we obtained normal hematofluorometer FEP levels of less than 30 micrograms/dL for men, and less than 40 micrograms/dL levels for women. We have evaluated a hematofluorometer against a standard microextraction procedure and feel that the hematofluorometer is superior for clinical laboratories if elevated FEPs are confirmed by retesting with washed RBC. In the second part of this paper we demonstrate the usefulness of the FEP in classifying microcytic RBC disorders in adults.

Red blood cells stored in saline solution for two weeks at 12 C lose some of their Fya, Fyb, and Fy3 antigenicity. At the same time substances with specific inhibitory activity against appropriate Duffy antibodies appear in the saline. Similar changes could not be recognized in time-expired commercial reagent red blood cell samples.

Absence of KX antigen and of normal expression of the Kell system antigens is associated with bizarre red blood cell morphology when observed by either light or scanning electron microscopy. Numerous acanthocytes and dacryocytes have been observed in the peripheral blood smear of an apparently healthy individual with McLeod-phenotype blood, in a male patient with type II chronic granulomatous disease who had a shortened 51Cr red blood cell survival time, and in a minor population of the red blood cells of his carrier mother.

Microcytic red blood cells (RBC) are commonly encountered in clinical medicine and are caused by disorders of heme synthesis [usually iron deficiency anemia (IDA) or anemia of chronic disease (ACD)] or disorders of globin synthesis (usually thalassemia syndromes or HbE). Using the clinical history and standard laboratory tests (hematocrit, per cent saturation of transferrin (% sat), serum ferritin, Hb electrophoresis, HBA2, and HbF) we classified 198 adults with microcytic RBC as follows: 48 IDA, 11 probable IDA, 11 iron-deficient erythropoiesis without anemia, 13 ACD, 42 alpha-thalassemia trait, 35 probable alpha-thalassemia trait, 20 beta-thalassemia trait, and 15 unclassified. In addition, we demonstrated that the FEP test reliably (83-90% of the time, depending on FEP methodology) classifies microcytic RBC states into disorders of heme synthesis vs. disorders of globin synthesis. Because of reliability and ease of measurement, we recommend the hematofluorometer FEP as the first step in the clinical laboratory evaluation of microcytic RBC disorders in both adults and children.

Red cells of the McLeod blood group phenotype have weak Kell antigens, lack Kx antigen and have acanthocytic morphology. We have immunoprecipitated Kell antigens from McLeod red cells and show that they are markers on the same 93 kDa membrane protein that carries Kell antigens on normal red cells. However, as determined by Western immunoblotting, McLeod red cells have a marked deficiency of this protein. We have also studied the near-neighbour relationship of McLeod and common Kell red-cell membrane proteins by cross-linking intrinsic sulphydryl groups by oxidation, catalysed with orthophenanthroline and copper, or by cross-linking amino groups with dimethyl-3,3'-dithiobispropionimidate. Results were analysed by diagonal mapping in two-dimensional gels. No abnormalities of membrane protein inter-relationship were detected in McLeod red cells. We have isolated Kx antigen from K0 red cells by immunoprecipitation with human alloimmune anti-Kx serum, isolation of immune complexes from detergent-solubilized cell membranes with protein A-Sepharose and analysis of the eluted immune complex by SDS-PAGE under reducing conditions. Kx antigen is a marker on a red-cell membrane protein of approximately 37 kDa. Ko (Knull) red cells have about twice the amount of Kx antigen as do red cells of common Kell type. McLeod red cells have no detectable Kx antigen by serological tests or by immunoprecipitation.

A 19-year old woman has been found whose red cells are a mixture of groups A1B (60%) and A1 (40%). Tests for many other genetic markers show no other evidence of mosaicism. She is not a twin and her parents and a sib are of normal ABO type. The cause of her dual population of red cells cannot be established, but may be an effect of somatic crossing over or mutation.