Detection of surface membrane antigens by a rosette assay using antibody coupled red cells

Possible aetiological factors in leukaemias in Africa

The hypothesis that the true incidence of c-ALL is relatively uniform throughout the world is not supported by experience in tropical Africa, where ALL is uncommon under five years of age. A high rate of spontaneous somatic mutation in pre-B cells may initiate the development of c-ALL, but its progress could be determined by (i) a leukaemogenic agent causing a second genetic event, (ii) the effects of intense antigenic barrage, either stimulating or suppressing pre-B-cell mitosis, or (iii) genetic determinants. Epidemiological patterns in populations of low, intermediate and high socio-economic status may be classified I-III with increasing incidence of diagnosed T-ALL in children over five years and c-ALL in younger children, and subclassified A and B with decreasing incidence of BL. There may be two forms of AML, one similar to that seen in industrialized countries, the other occurring at high prevalence in African children of low socio-economic status, often presenting with chloroma, and perhaps associated with immune suppression secondary to malnutrition, malaria and other intercurrent infections. Uncontrolled exposure to petroleum and other chemicals, and the use of alkylating agents in treatment of neoplasms in young patients could emerge as important causes of ANLL in Africa. There are two varieties of CLL also, one similar to that seen in the western world, the other prevalent in adults below 45 years of age, especially women: transmission of a leukaemogenic agent is postulated, to which women are more susceptible due to immunosuppression during normal pregnancy. The human population and some subhuman primates of subSaharan Africa are the largest reservoir of HTLV-1, which shows association with B-CLL over 50 years of age and ATL.

Antibodies to HTLV-I in Nigerian blood-donors, their relatives and patients with leukaemias, lymphomas and other diseases

Antibodies to HTLV-I have been detected in sera from 15 (2.0%) of 736 adult blood-donors in Nigeria, in 4 (20.0%) of 20 patients with chronic lymphatic leukaemia, 3 (10.0%) of 30 with non-Hodgkin's lymphoma, one of 12 with Burkitt's lymphoma and one of 7 with acute lymphoblastic leukaemia. The frequency of positivity was higher (3.6%) in the blood-donors from the guinea and wooded savanna of northern Nigeria than in those from the rain-forest and mangrove swamps of southern Nigeria (1.8% in Lagos and 0.7% in Calabar). Two of the 3 seropositive patients with lymphoma had clinical presentation and courses similar to those of Japanese and Caribbean patients with adult T-cell leukaemia/lymphoma.

Direct antibody rosette-forming reactions using monoclonal markers of lymphocyte subpopulations. Methodology and applications illustrated by investigations with rat pan-T antibodies of the CAMPATH series

A sensitive direct antibody rosette assay has been developed for the detection of antigens on the lymphocyte cell membrane. Indicator cells for rosette tests were prepared by chromic chloride coupling of rat or mouse monoclonal IgG or IgM anti-lymphocyte antibodies to untreated or trypsinized bovine red blood cells. The monoclonal antibodies used were reactive with a range of cell surface markers which identify various lymphocyte subpopulations, including T cell antigens, HLA class II (Ia-like antigens), Leu-7 (HNK-1) and VEP 13, a determinant of Fc gamma receptors on large granular lymphocytes. Results obtained by direct rosette formation correlated well with those of parallel tests using indirect immunofluorescent antibodies staining. Several applications of the direct antibody rosetting procedure are described in further investigations with a series of pan-T monoclonal (CAMPATH) antibodies. These include the morphological examination of antibody-binding cells in cytocentrifuge smears, the separation of lymphocyte subsets by density gradient centrifugation, and the use of a rosette inhibition assay to identify monoclonal antibodies binding to the same (or closely associated) epitopes of the lymphocyte cell membrane.

A bibliography of the leukaemias in Africa, 1904-1985

A bibliography of leukaemias in Africa is presented from 1904 to 1985. The literature is listed chronologically and is classified geographically (north, south, east and west Africa) and by leukaemia type. The epidemiology of leukaemias in Africa is discussed briefly, especially as to the rarity of acute lymphoblastic leukaemia under the age of four years, the frequency of chloroma, the young age of presentation of chronic granulocytic leukaemia, the frequency of chronic lymphatic leukaemia in adults, especially women, under 45 years in tropical Africa, and the frequency of infection by the human T-cell leukaemia-lymphoma (or lymphotropic) virus type I and of adult T-cell leukaemia-lymphoma.