Leukemias and lympomas: Immunophenotyping (evaluation of cell surface markers), diagnosis, detection of minimal residual disease, and to identify prognostically important subgroups. Paroxysmal nocturnal hemoglobinuria: Deficiency of CD 55 and CD 59. Hematopoietic stem cell transplantation: Enumeration of CD34+ stem cells. Feto-maternal hemorrhage: Detection and quantitation of foetal hemoglobin in maternal blood sample. Anemias: Reticulocyte count. Human immunodeficiency virus infection: For enumeration of CD4+ lymphocytes. Histocompatibility cross matching.