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NEW IDEAS ON MYELOID LEUKAEMIA
546
that is no new predicament for researchit may have to be resolved more plainly than hitherto if the " service " men are to emerge in quantity and to occupy themselves with questions which are " real " in Government terms. But what are the questions ? And when they have been formulated, will the responses come in anything like precise words-given present research definitions and investigative resources ? Perhaps the customer-contractor mechanism of the Rothschild report presupposes a set of tidy cut-and-dried answers which can seldom be uncovered. Anyway, to fortify the research apparatus, new elements have been introduced into the Department’s structure, notably those which aim to combine the efforts of the central planning machine, of all kinds of research-workers, and of a powerful force of scientific advisers. If a shrewd policy for N.H.S. research is to emerge, the response from the front line must be a turn of thought by which to sense more readily Government headaches as Governments and their advisers feel them, to take research opportunities not only for their interest but also for their relevance, to explore all possible improvements in the collection and distribution of information, and to dismantle such barriers as now exist in community medicine (with all the synonyms) between its academic, research, and service features. If the outcome is, for the time being, a range of uncertain answers, they must be used as best they can: " informed guesses " may be greatly superior to protracted inactivity, while everyone waits for data to accumulate and sharper analyses to emerge. Certainly, for the N.H.S., the impact of these endeavours may make decisions no easier, but they can hardly fail to make them less tentative and more fruitful. The final test of all innovation which be thus may proposed is to ask: is it designed chiefly for the smoother running of an existing part of the system ? ; or is its prime purpose the benefit of the sick and the deprived ? The reasons do not always coincide; and one of the functions of the new community health councils is to point out when they do not.
Though workers,
NEW IDEAS ON MYELOID LEUKAEMIA
AMONG the techniques which have changed ideas about normal heemopoiesis1 is the agar-culture method devised by Metcalf and his colleagues working in Melbourne, Australia. This work has now been extended to the study of myeloid leuksemias, and Metcalf2 has given a stimulating account of progress. He begins by stating that today we recognise two types of neoplasia-a type in which mutations in the cells have rendered growth and proliferation insusceptible to regulatory control, and a type in which the cells " are driven to proliferate exponentially by an abnormal balance of regulatory factors ". The distinction between these two types is not, he says, an academic exercise. " Attempts at therapy of leukasmia using cytotoxic drugs or immunological methods are justified if the leukxmic cells are indeed clones of cells with intrinsic irreversible abnormalities. If, however, leukasmic cells are behaving in an abnormal manner 1. 2.
Lancet, 1972, i, 1056. Metcalf, D. The Nature of Myeloid Leukaemia. 9th Annual Guest Lecture, Leukaemia Research Fund. London, 1973.
mainly because of abnormal regulation, then clearly therapeutic efforts should be directed towards correcting regulator imbalance rather than the elimination of cells which might be essentially normal." In order to investigate this question, he prefers to study the cells of human leukaemic patients rather than those from mice with transmitted leukaemias. Like several of his predecessors he regards mouse leukxmias as " unsatisfactory, possibly quite misleading, models of the various leukaemias of humans ". Consequently he and his colleagues have concentrated on the use of cells from human myeloid leukxmias and studied their properties when grown in vitro by their agarculture technique. Agar cultures are an efficient method of studying colony-forming cells (c.F.c.s) and their response to colony-stimulating (c-s) factors. c.F.c.s in man are found in marrow, spleen, and blood, normally mostly in marrow; they can be partly separated from other haemopoietic cells by physical methods. In 7 days the c.F.c.s planted on agar produce colonies of 50 to 2000 cells and some " clusters " of 3 to 50 cells. c.F.c.s when stimulated by c-s factor produce colonies consisting mostly of granulocytic cells, but later monocytes appear and these, if the culture is kept going long enough, will replace the granulocytes. In cultures of human cells monocytes appear late, so that with the usual period of 7 days’ incubation before analysis most of the colonies consist of granulocytes
only.
Colony-stimulating factors
are
glycoproteins
found in urine, serum, and most tissues; the factors from different sources differ in structure and molecular size. For practical purposes leucocytes from peripheral blood are the best source, the factor coming mainly from the monocytes present since the polymorphs do not produce it. Probably local production of c-s factor in the marrow is very important in determining the concentration of factors impinging on target c.F.c.s. In addition c-s-factor inhibitors have been found in normal serum; they are not toxic for c.F.c.s nor for the colony cells formed from them, but they prevent the stimulating activity of the c-s factor; they seem to be species-specific. Abnormalities in c-s-factor activity and in c.F.c. development have been found in myeloid leukaemia. In acute myeloid and myelomonocytic leukaemias, serum c-s-factor activity is raised in about a third of the cases; in chronic myeloid leukaemia the factor was increased in 46% of untreated cases and in 88% of sera from patients showing transformation from chronic to acute myeloid leukaemia. In the acute cases the c-s-factor inhibitors were much reduced in 57% of the cases, whereas in the chronic patients the serum levels were mostly normal. However, one of the difficulties in interpreting these changes is that the presence of active infection raises the serum c-s-factor levels, and many of the acute leukaemia patients had such infections at the time. The important point, Metcalf believes, is the net excess of c-s-factor production over c-s-factor-inhibitor activity in these leukxmias, leading to an abnormality in the regulation of cell proliferation. Some possibly preleukaemic cases were also examined, such as myelofibrosis and polycythxmia; a proportion of these also showed imbalance of c-s factor and c-s-factor inhibitor, whereas other
547
patients with neoplastic conditions such as lymphoma or non-neoplastic diseases did not show this change. In colony-forming-cell development there are striking differences between chronic and acute myeloid leukxmias. In chronic myeloid leukaemia c.F.c.s from blood and marrow produce colonies that mature into granulocytes, but there are some abnormalities. There is an abnormally high frequency of colonies produced from a given number of cultured cells; and, whereas in normal persons the frequency of c.F.c.s in the blood is a hundred times less than the frequency in the marrow, in chronic myeloid leukaemia the ratio is reversed and the frequency of c.F.c.s in blood may be very high. Then, although most of the c.F.c.s mature normally into granulocytes, the development of monocytes (macrophages) tends to be premature, and abnormalities in the timing of mitotic cycles can be found. Finally, most of the dividing cells show the characteristic Philadelphia chromosome. So Metcalf concludes that the granulocytes in this leukaemia are members of an abnormal clone. When the picture changes towards an acute blast type of leukaemia there is progressive loss of c.F.c.s, and eventually most cells fail to mature in vitro. In acute myeloid and myelomonocytic leukxmias the cultures of cells from blood and marrow behave quite differently. In cultures from 67 patients examined before treatment 20 % of the cells failed to proliferate at all, and 60-70 % formed small clusters of 3 to 40 cells but no aggregates large enough to be classified as colonies. Most cells seem to attempt differentiation, but this is ineffective and abnormalities in nucleus and cytoplasm are common. So the proliferating cells can be regarded as members of an abnormal clone which has replaced or suppressed normal granulopoiesis. An odd feature noticed was an " intriguing waxing and waning in normal and leukaemic granulocyte populations which is quite unlike the behaviour of neoplastic populations " and also unlike the change in chronic myeloid leukaemia which seems to be permanent and complete. Metcalf and his colleagues regard the cells in acute myeloid leukaemias as cells that exhibit heritable intrinsic changes and are not normal cells behaving in an abnormal manner in vivo simply because of regulator imbalances. In chronic myeloid leukaemia the presence of an abnormal chromosome, also seen in red-cell and megakaryocyte precursors, shows the presence of an abnormal clone, but the in-vitro behaviour of the c.F.c.s is essentially normal, and, though some abnormalities of cell properties have been found, these " are not necessarily indicative of intrinsic irreversible changes " since they are no more than those they found in a study of c.F.c.s from normal fetal liver. They attach weight to the finding that c.F.c.s from both chronic and acute forms of this leukxmia remain responsive to c-s factor; in chronic leukaemia responsiveness is somewhat diminished, and in acute leukaemia rather more than normal. When acute myeloid leukaemia goes into remission the c.F.c.s then respond normally to c-s factor. The abnormalities in actual c-s-factor activity have already been mentioned. Similar differences have been found in some patients with conditions regarded as preleukaemic. Such cases are infrequent, but sometimes it can be important to decide soon whether a leuco-
erythroblastic picture, for example, is simply reactive or indicative of an early stage of a leukaemia. Metcalf describes a " simple test ", using the agar-culture method, which needs only materials to be found in most hospital haematology departments and will give in 7 days reliable information about the presence of abnormal cells in blood or marrow samples. So far as they have pursued their studies, Metcalf and his group have reached "
some
conclusions:
The
picture of myeloid leukaemia in humans which is becoming clear from recent in vitro studies is that these diseases involve the progressive emergence of abnormal clonally-dominant, granulocytic populations. The abnormal populations are not autonomous cancer cells and their progressive proliferation occurs in the presence of, and may depend on, gross abnormalities in the regulatory mechanisms controlling granulopoiesis. While this new insight into the nature of myeloid leukaemia offers no immediate prospects for improved therapy or preventive measures, it must ultimately lead to the development of more satisfactory methods for controlling the emergence and proliferation of leukoemic cells."
FUTURE OF THE COMMUNITY PHYSICIAN
A MEETING in Edinburgh this month of the Faculty of Community Medicine seemingly was something of a rite de passage. " Goodbye, Medical Officers of Health " was the message given by Dr Henry Yellowlees (the c.M.o.oftheD.H.S.S.),and goodbye much else besides. The first day in April sees the reorganisation of the National Health Service, and all sorts of familiar actors will vanish from the stage. s.A.M.o.s will take a last bow. The traditional academic department of social medicine will have to rethink its role. Goodbye more than anything else (said Dr Yellowlees) to the notion that anyone at the centre has the right and the remit to determine the details of health care in the individual parish. New administrations are going to have to define entirely new roles, and all is change. But at this same meeting Sir Richard Doll gave a timely reminder that whatever the administrators may be doing, whatever the courses that may be instituted, whatever the new or old wine in old or new bottles, behind all this there are fundamental matters relating to hard and essential aspects of the community’s health to which medicine has still to address itself. Beyond the committees, there is the fact that people (in large numbers) are living and dying, and it is the business of medicine more closely to understand the major causes of the mortalities of our times, and to do something real about prevention. N.H.S. reorganisation is important, but when the dust has settled let us still address ourselves to such questions as why, in 1970, the Swedish infant mortality and prenatal rates were, respectively, 36% and 31% below those in England and Wales. " We need " said Sir Richard " to inquire how far these differences can be attributed to differences in classification, medical care, and the environment-particularly, perhaps, in the socioeconomic conditions of the least favoured Information on the sections of the community." epidemiology both of ischxmic heart-disease and of various types of cancer can leave no doubt at all that
mortality
that is no new predicament for researchit may have to be resolved more plainly than hitherto if the " service " men are to emerge in quantity and to occupy themselves with questions which are " real " in Government terms. But what are the questions ? And when they have been formulated, will the responses come in anything like precise words-given present research definitions and investigative resources ? Perhaps the customer-contractor mechanism of the Rothschild report presupposes a set of tidy cut-and-dried answers which can seldom be uncovered. Anyway, to fortify the research apparatus, new elements have been introduced into the Department’s structure, notably those which aim to combine the efforts of the central planning machine, of all kinds of research-workers, and of a powerful force of scientific advisers. If a shrewd policy for N.H.S. research is to emerge, the response from the front line must be a turn of thought by which to sense more readily Government headaches as Governments and their advisers feel them, to take research opportunities not only for their interest but also for their relevance, to explore all possible improvements in the collection and distribution of information, and to dismantle such barriers as now exist in community medicine (with all the synonyms) between its academic, research, and service features. If the outcome is, for the time being, a range of uncertain answers, they must be used as best they can: " informed guesses " may be greatly superior to protracted inactivity, while everyone waits for data to accumulate and sharper analyses to emerge. Certainly, for the N.H.S., the impact of these endeavours may make decisions no easier, but they can hardly fail to make them less tentative and more fruitful. The final test of all innovation which be thus may proposed is to ask: is it designed chiefly for the smoother running of an existing part of the system ? ; or is its prime purpose the benefit of the sick and the deprived ? The reasons do not always coincide; and one of the functions of the new community health councils is to point out when they do not.
Though workers,
NEW IDEAS ON MYELOID LEUKAEMIA
AMONG the techniques which have changed ideas about normal heemopoiesis1 is the agar-culture method devised by Metcalf and his colleagues working in Melbourne, Australia. This work has now been extended to the study of myeloid leuksemias, and Metcalf2 has given a stimulating account of progress. He begins by stating that today we recognise two types of neoplasia-a type in which mutations in the cells have rendered growth and proliferation insusceptible to regulatory control, and a type in which the cells " are driven to proliferate exponentially by an abnormal balance of regulatory factors ". The distinction between these two types is not, he says, an academic exercise. " Attempts at therapy of leukasmia using cytotoxic drugs or immunological methods are justified if the leukxmic cells are indeed clones of cells with intrinsic irreversible abnormalities. If, however, leukasmic cells are behaving in an abnormal manner 1. 2.
Lancet, 1972, i, 1056. Metcalf, D. The Nature of Myeloid Leukaemia. 9th Annual Guest Lecture, Leukaemia Research Fund. London, 1973.
mainly because of abnormal regulation, then clearly therapeutic efforts should be directed towards correcting regulator imbalance rather than the elimination of cells which might be essentially normal." In order to investigate this question, he prefers to study the cells of human leukaemic patients rather than those from mice with transmitted leukaemias. Like several of his predecessors he regards mouse leukxmias as " unsatisfactory, possibly quite misleading, models of the various leukaemias of humans ". Consequently he and his colleagues have concentrated on the use of cells from human myeloid leukxmias and studied their properties when grown in vitro by their agarculture technique. Agar cultures are an efficient method of studying colony-forming cells (c.F.c.s) and their response to colony-stimulating (c-s) factors. c.F.c.s in man are found in marrow, spleen, and blood, normally mostly in marrow; they can be partly separated from other haemopoietic cells by physical methods. In 7 days the c.F.c.s planted on agar produce colonies of 50 to 2000 cells and some " clusters " of 3 to 50 cells. c.F.c.s when stimulated by c-s factor produce colonies consisting mostly of granulocytic cells, but later monocytes appear and these, if the culture is kept going long enough, will replace the granulocytes. In cultures of human cells monocytes appear late, so that with the usual period of 7 days’ incubation before analysis most of the colonies consist of granulocytes
only.
Colony-stimulating factors
are
glycoproteins
found in urine, serum, and most tissues; the factors from different sources differ in structure and molecular size. For practical purposes leucocytes from peripheral blood are the best source, the factor coming mainly from the monocytes present since the polymorphs do not produce it. Probably local production of c-s factor in the marrow is very important in determining the concentration of factors impinging on target c.F.c.s. In addition c-s-factor inhibitors have been found in normal serum; they are not toxic for c.F.c.s nor for the colony cells formed from them, but they prevent the stimulating activity of the c-s factor; they seem to be species-specific. Abnormalities in c-s-factor activity and in c.F.c. development have been found in myeloid leukaemia. In acute myeloid and myelomonocytic leukaemias, serum c-s-factor activity is raised in about a third of the cases; in chronic myeloid leukaemia the factor was increased in 46% of untreated cases and in 88% of sera from patients showing transformation from chronic to acute myeloid leukaemia. In the acute cases the c-s-factor inhibitors were much reduced in 57% of the cases, whereas in the chronic patients the serum levels were mostly normal. However, one of the difficulties in interpreting these changes is that the presence of active infection raises the serum c-s-factor levels, and many of the acute leukaemia patients had such infections at the time. The important point, Metcalf believes, is the net excess of c-s-factor production over c-s-factor-inhibitor activity in these leukxmias, leading to an abnormality in the regulation of cell proliferation. Some possibly preleukaemic cases were also examined, such as myelofibrosis and polycythxmia; a proportion of these also showed imbalance of c-s factor and c-s-factor inhibitor, whereas other
547
patients with neoplastic conditions such as lymphoma or non-neoplastic diseases did not show this change. In colony-forming-cell development there are striking differences between chronic and acute myeloid leukxmias. In chronic myeloid leukaemia c.F.c.s from blood and marrow produce colonies that mature into granulocytes, but there are some abnormalities. There is an abnormally high frequency of colonies produced from a given number of cultured cells; and, whereas in normal persons the frequency of c.F.c.s in the blood is a hundred times less than the frequency in the marrow, in chronic myeloid leukaemia the ratio is reversed and the frequency of c.F.c.s in blood may be very high. Then, although most of the c.F.c.s mature normally into granulocytes, the development of monocytes (macrophages) tends to be premature, and abnormalities in the timing of mitotic cycles can be found. Finally, most of the dividing cells show the characteristic Philadelphia chromosome. So Metcalf concludes that the granulocytes in this leukaemia are members of an abnormal clone. When the picture changes towards an acute blast type of leukaemia there is progressive loss of c.F.c.s, and eventually most cells fail to mature in vitro. In acute myeloid and myelomonocytic leukxmias the cultures of cells from blood and marrow behave quite differently. In cultures from 67 patients examined before treatment 20 % of the cells failed to proliferate at all, and 60-70 % formed small clusters of 3 to 40 cells but no aggregates large enough to be classified as colonies. Most cells seem to attempt differentiation, but this is ineffective and abnormalities in nucleus and cytoplasm are common. So the proliferating cells can be regarded as members of an abnormal clone which has replaced or suppressed normal granulopoiesis. An odd feature noticed was an " intriguing waxing and waning in normal and leukaemic granulocyte populations which is quite unlike the behaviour of neoplastic populations " and also unlike the change in chronic myeloid leukaemia which seems to be permanent and complete. Metcalf and his colleagues regard the cells in acute myeloid leukaemias as cells that exhibit heritable intrinsic changes and are not normal cells behaving in an abnormal manner in vivo simply because of regulator imbalances. In chronic myeloid leukaemia the presence of an abnormal chromosome, also seen in red-cell and megakaryocyte precursors, shows the presence of an abnormal clone, but the in-vitro behaviour of the c.F.c.s is essentially normal, and, though some abnormalities of cell properties have been found, these " are not necessarily indicative of intrinsic irreversible changes " since they are no more than those they found in a study of c.F.c.s from normal fetal liver. They attach weight to the finding that c.F.c.s from both chronic and acute forms of this leukxmia remain responsive to c-s factor; in chronic leukaemia responsiveness is somewhat diminished, and in acute leukaemia rather more than normal. When acute myeloid leukaemia goes into remission the c.F.c.s then respond normally to c-s factor. The abnormalities in actual c-s-factor activity have already been mentioned. Similar differences have been found in some patients with conditions regarded as preleukaemic. Such cases are infrequent, but sometimes it can be important to decide soon whether a leuco-
erythroblastic picture, for example, is simply reactive or indicative of an early stage of a leukaemia. Metcalf describes a " simple test ", using the agar-culture method, which needs only materials to be found in most hospital haematology departments and will give in 7 days reliable information about the presence of abnormal cells in blood or marrow samples. So far as they have pursued their studies, Metcalf and his group have reached "
some
conclusions:
The
picture of myeloid leukaemia in humans which is becoming clear from recent in vitro studies is that these diseases involve the progressive emergence of abnormal clonally-dominant, granulocytic populations. The abnormal populations are not autonomous cancer cells and their progressive proliferation occurs in the presence of, and may depend on, gross abnormalities in the regulatory mechanisms controlling granulopoiesis. While this new insight into the nature of myeloid leukaemia offers no immediate prospects for improved therapy or preventive measures, it must ultimately lead to the development of more satisfactory methods for controlling the emergence and proliferation of leukoemic cells."
FUTURE OF THE COMMUNITY PHYSICIAN
A MEETING in Edinburgh this month of the Faculty of Community Medicine seemingly was something of a rite de passage. " Goodbye, Medical Officers of Health " was the message given by Dr Henry Yellowlees (the c.M.o.oftheD.H.S.S.),and goodbye much else besides. The first day in April sees the reorganisation of the National Health Service, and all sorts of familiar actors will vanish from the stage. s.A.M.o.s will take a last bow. The traditional academic department of social medicine will have to rethink its role. Goodbye more than anything else (said Dr Yellowlees) to the notion that anyone at the centre has the right and the remit to determine the details of health care in the individual parish. New administrations are going to have to define entirely new roles, and all is change. But at this same meeting Sir Richard Doll gave a timely reminder that whatever the administrators may be doing, whatever the courses that may be instituted, whatever the new or old wine in old or new bottles, behind all this there are fundamental matters relating to hard and essential aspects of the community’s health to which medicine has still to address itself. Beyond the committees, there is the fact that people (in large numbers) are living and dying, and it is the business of medicine more closely to understand the major causes of the mortalities of our times, and to do something real about prevention. N.H.S. reorganisation is important, but when the dust has settled let us still address ourselves to such questions as why, in 1970, the Swedish infant mortality and prenatal rates were, respectively, 36% and 31% below those in England and Wales. " We need " said Sir Richard " to inquire how far these differences can be attributed to differences in classification, medical care, and the environment-particularly, perhaps, in the socioeconomic conditions of the least favoured Information on the sections of the community." epidemiology both of ischxmic heart-disease and of various types of cancer can leave no doubt at all that
mortality