Subdivision of the acute non-lymphoblastic leukaemias by measurement of the relative abundance of a specific RNA sequence.

A recombinant plasmid library representing the more abundant polyadenylated RNA of a relapsed acute myelomonocytic leukaemic (FAB class M4) has been constructed. One recombinant, designated pAM6, contains a DNA sequence complementary to an RNA of about 1100 nucleotides in length. The relative concentrations of pAM6 RNA in the RNAs from cloned human haematopoietic cell lines and from fractionated leukaemic leukocytes and normal bone marrow cells, measured by an RNA dot hybridization method, indicated that pAM6 RNA occurs in myeloid cells, probably those of the monocyte lineage at the earlier stages in differentiation. Similar assays showed that pAM6 RNA could not be detected in the peripheral blood leukocytes of normal individuals, or of ALL and CLL patients, but that the relative abundance of pAM6 RNA varied widely in leukocytes from CGL chronic phase, CGL acute phase, and ANLL. No correlation between pAM6 RNA occurrence and FAB classification of ANLL could be made; thus it would appear that the relative abundance of pAM6 RNA in ANLL leukocytes can be used to subdivide the ANLLs in a novel manner. It is suggested that this criterion, in conjunction with existing diagnostic markers, may provide a subclassification of the ANLLs that could be of some prognostic and therapeutic value.

Expression of the myc gene locus in populations of leukocytes from leukaemia patients and normal individuals.

The relative abundances of c-myc-related RNA in the total cellular RNA of peripheral blood leukocytes from 36 patients with leukaemia have been compared with those in normal peripheral blood leukocytes and in HL60 cells. Varying amounts of c-myc-related RNA were found in RNAs from leukocytes from patients with ANLL, CGL and ALL. High concentrations (comparable with that in HL60 cells) were found in 13 (36%) of the leukaemias and lower, but still significant, concentrations in a further 15 (42%). Low concentrations of c-myc-related RNA, comparable to that in normal leukocytes, were found in 2 of 8 CGLs, 1 of 12 ANLLs, and 5 of 5 CLLs. DNAs from 11 leukaemia patients' leukocytes, in which c-myc-related RNA concentrations ranged from very high to very low, were examined for rearrangements and/or amplification of the c-myc gene. No rearrangements were detected, and the small degree of amplification (2- to 4-fold at most) found was not correlated with increased levels of c-myc RNA. There was, however, a noteworthy (though incomplete) correlation between elevated levels of c-myc-related RNA and the occurrence of higher proportions of blast cells in leukocyte populations from leukaemic patients. It is suggested that high levels of c-myc-related RNA in a population of peripheral blood leukocytes indicate the presence of a high proportion of leukaemic leukocytes that are maturation-arrested at early stages of development.

Lineage-specific and differentiation-stage-specific gene expression in normal and leukaemic human myeloid cells.

One example of each of two approaches to the isolation of molecular hybridization probes and their use for the comparative investigation of gene expression and its control during differentiation of normal and leukaemic leukocytes is described. RNA preparations from the peripheral blood leukocytes of human leukaemias of various types were assayed for the relative abundance of the mRNA homologous with a cellular oncogene, c-myc. All types of leukaemia except chronic lymphatic leukaemia (CLL) showed varying levels of myc-related RNA; the highest concentrations occurred in cell populations in which blast cells predominated. In contrast, a recombinant plasmid (pCG14), isolated from a cDNA recombinant plasmid library that represented polyadenylated RNAs from the peripheral blood leukocytes of a chronic granulocytic leukaemia (CGL), hybridized with an mRNA whose occurrence is diagnostic of CGL leukocytes. This mRNA was also found in normal bone marrow cells; in both bone marrow and in CGL leukocytes, pCG14-homologous RNA occurs only in cells around the myelocyte stage in differentiation. It is suggested that these probes, and others for mRNAs whose occurrence is specific to a particular cell lineage and/or stage in differentiation, detect a new series of potential diagnostic markers. These might usefully supplement existing ones to provide a more detailed, objective subclassification of the leukaemias which could have important implications for diagnosis and therapy.

A review of the biological and potential therapeutic actions of Harpagophytum procumbens.

Harpagophytum procumbens (Hp), commonly known as Devil's Claw is a perennial plant which thrives in arid conditions. For centuries, it has been used as a traditional treatment for a variety of illnesses, including fevers, skin complaints, arthritis and diseases of the digestive tract as well as an appetite stimulant. Since its introduction to Europe in the early twentieth century, it has become a popular antiinflammatory and analgesic preparation amongst herbalists for supportive or adjuvant treatment of degenerative joint diseases, tendonitis, headache, backache and menstrual pain. The validity of Hp as an effective antiinflammatory and analgesic preparation, particularly in the relief of arthritic symptoms, has been investigated in numerous animal, clinical and in vitro studies. Although some contradictory evidence exists, the majority of animal studies appear to indicate Hp as an effective antiinflammatory and analgesic preparation in the treatment of acute and subacute inflammation. Clinical trials support Hp as a beneficial treatment for the alleviation of pain and improvement of mobility in a variety of musculoskeletal conditions. Analysis of the in vitro and ex vivo studies that currently exist, indicate that Hp has significant effects on numerous proinflammatory markers. However, the exact mechanism(s) by which Hp may reduce inflammation remain to be elucidated.

A new approach to the classification of human leukaemias: measurement of the relative abundance of a specific RNA sequence by means of molecular hybridisation.

A recombinant plasmid library representing polyadenylated RNAs in the leucocytes of a Ph1-positive chronic granulocytic leukaemia (CGL) has been constructed. One recombinant (designated pCG14) isolated from this library contains a DNA sequence complementary to a small polyadenylated RNA that is abundant in RNA from CGL leucocytes. The relative concentrations of pCG14 RNA in the RNAs from a variety of normal and leukaemic leucocytes and human haemopoietic cell lines have been measured with a molecular hybridisation assay. This has shown that pCG14 RNA is 10 to 50 times more abundant in RNA from CGL leucocytes than in the RNAs from these other cells. The data indicate that the occurrence of pCG14 RNA in high abundance is sufficiently characteristic of a CGL leucocyte population to distinguish it from other populations of leucocytes. They suggest that the measurement of the concentrations of specific RNA species in leucocyte RNA by means of molecular hybridisation with cloned complementary DNAs may provide additional markers for the objective classification of human leukaemias which could be particularly useful since the method exploits a criterion different from any currently in use.