Summary. In this study, we evaluated the suitability of the calcein assay as a routine clinical laboratory method for the identification of multidrug-resistant phenotype in acute leukaemia. This study presents the results of the calcein tests obtained in two large haematological centres in Hungary. Assays were performed with blast cells of 93 de novo acute leukaemia patients, including 65 patients with acute myeloid leukaemia (AML). Results were expressed as multidrug resistance activity factor (MAF) values. AML patients were divided into responders and non-responders and MAF values were calculated for each group. In both centres, responder patients displayed significantly lower MAF values than non-responders (P 0´0045 and P 0´0454). Cut-off values were established between the MAF R 1 SEM and MAF NR 2 SEM values. On the basis of these cut-off levels, multidrug resistance (MDR) negativity showed a 72% predictive value for the response to chemotherapy, whereas MDR positivity was found to have an average predictive value of 69% for therapy failure. MDR activity was a prognostic factor for survival rate and the test was suitable for detecting patients at relapse. The calcein assay can be used as a quantitative, standardized, inexpensive screening test in a routine clinical laboratory setting. The assay detects both P-glycoprotein and multidrug resistance-associated protein activities, and identifies AML patients with unfavourable therapy responses.

Using the single-strand conformation polymorphism and heteroduplex analyses, the P53 and RB genes were analyzed in cell samples from twenty-eight patients with chronic myeloid leukemia (CML) both at diagnosis and at the onset of accelerated phase (AP) of the disease. No alterations of the P53 or RB genes were found in any of the chronic phase (CP) samples. Structural abnormalities of the P53 gene were observed in ten of twenty-eight AP samples within exons 4, 5, 7 and 9. Of the ten cases of AP disease with altered P53 genes, five patients also suffered from the deletion of the other allele. Alterations of the RB gene could be detected in six AP samples, and aberrant band patterns were found in the analysis of exons 2, 3, 4, 6, 7, 13, 14, 17, 21 and 26. Among the six AP samples with structural abnormalities of the RB gene, two showed the loss of the other allele. It is of note that alterations of both P53 and RB genes were observed in two AP samples. Our data strongly suggest that abnormalities of the P53 and RB genes and acceleration of CML are linked events in some cases of AP.

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Large numbers of papers have been published on the relationship of different diseases and human blood-groups. Comparing blood-group distribution of a great number of patients suffering from acute leukaemia (AL) to that of control persons, no significant differences could be detected (Shirley & Desai, 1965; Vogel & Helmbold, 1972; Harris et al, 1977).We found blood-group 0 frequency surprisingly high among female patients with AL treated in our clinic between 1974 and 1980. Therefore blood-group distribution of patients related to sex was studied. Data of 45 female and 69 male patients are summarized in Table 1. Women suffering from AL have significantly more blood-group 0 than men (51 % and 22%, respectively; x2 = 11.1 1, significant difference). Blood-group A occurred more often (46%) in men with AL than in women (33%). When comparing different types of AL-though our case-number is rather limited-it could be pointed out that blood-group 0 was in highest frequency in women with acute lymphoid leukaemia (62%), while it was less often present in men with acute myeloid leukaemia (21%).These results were compared to blood-group frequency in Hungary. Blood-group 0 occurs in 30-32% of the whole Hungarian population without considerable differences among the different regions (Rex-Kiss & Szabit, 1979). There was no difference when a comparison was made between blood-group distribution of patients with AL and that of a healthy population. However, in group 0 a sex-linked difference was evident. A similar difference in blood-group frequency of a healthy population seems to be rather improbable and no data supporting it are available in the literature.The probable importance of sex differences in blood-group distribution of patients with AL has not been emphasized yet. However, studying retrospectively Mustacchi's earlier report (1960) on 570 patients with AL a similar distribution could be detected. 41 % ofpatients Changes in blood-group characteristics of patients with AL in the course ofdisease are well known but it cannot be used for explaining sex differences in blood-group distribution.