Characterization of Thy-1 (CDw90) expression in CD34+ acute leukemia

Thy-1 (CDw90) is a phosphatidylinositol-anchored cell surface molecule which, when coexpressed with CD34 in normal human bone marrow, identifies a population of immature cells that includes putative hematopoietic stem cells. To date, the characterization of Thy-1 expression has been confined largely to normal tissues and cell lines. In this study, we evaluated the frequency and intensity of Thy-1 expression as defined by reactivity with the anti-Thy-1 antibody 5E10 in 38 cases of CD34+ acute leukemia (21 acute myelogenous leukemia [AML], 8 chronic myelogenous leukemia [CML] in blast crisis, and 9 acute lymphoblastic leukemia [ALL]). In 34 of 38 cases (89%) the CD34+ cells lacked expression of the Thy-1 antigen. High-density Thy-1 expression was found in 1 case of CML in lymphoid blast crisis, and low- density Thy-1 expression was identified on a portion of the leukemic cells in 2 cases of AML with myelodysplastic features, and 1 case of CML in myeloid blast crisis, suggesting a possible correlation between Thy-1 expression and certain instances of stem cell disorders such as CML and AML with dysplastic features. In contrast, the dissociation of Thy-1 and CD34 expression in the majority of acute leukemias studied suggests that the development of these leukemias occurs at a later stage than the hematopoietic stem cell. Characterization of Thy-1 expression in acute leukemia may eventually provide insights into the origin of the disease. In addition, separation of leukemic blasts from normal stem cells based on Thy-1 expression may prove useful in assessing residual disease, as well as in excluding leukemic blasts from stem cell preparations destined for autologous bone marrow or peripheral stem cell transplantation.     

A survey of hepatitis B surface antigen-positive blood donors: degree of understanding and action taken after notification

All blood donors in the United States are tested for hepatitis B surface antigen (HBsAg) upon donation; if the test result is positive, the primary method of notification is by letter. To assess the effectiveness of this notification methods in stimulating HBsAg-positive donors to seek medical care and take preventive measures, 54 donors who tested HBsAg-positive on donation at the American Red Cross Blood Services. Atlanta Region, from January 1987 to July 1989 were interviewed. Thirty-nine donors (72%) had sought medical care after notification; the only motivating factor was that the letter told the donor to consult with his or her physician. Compared with donors who did not seek medical care, donors who did so were more likely to understand that the blood test was abnormal or that they were infected, and they were more likely to understand how hepatitis B virus is transmitted and that a vaccine is available. The differences were not significant, however. Of those donors who sought medical care, less than half received appropriate recommendations for protection of contacts, and of those who did, only one-third received prophylaxis. In-person and telephone interviews with donors, revision of the notification letter, and hepatitis B education programs targeted at medical care providers are suggested.