FACTOR-VIII INHIBITOR BYPASSING ACTIVITY

43

SEQUENTIAL FETUS-FETUS INTERACTION AND C.N.S. DEFECTS

SIR,-Since our previous letter’

have examined our data of Knox’s revised hypothesis.2 Knox has suggested "that a quarter to a third of anencephalus/spina bifida occurrences at birth ranks 2 or higher depend upon sequential interaction between successive fullterm sibs, and that the remaining two-thirds to threequarters depend upon simultaneous interactions" which may involve twins or residual tissue from an immediately previous abortion. The "sequential" hypothesis was based on two observations : a decreased interval between the immediately previous (i.p.) sib and the affected sib, observed by Record and McKeown in 1950,3 and the sex ratio of the i.p. sibs which varied according to the sex of the affected individual. Knox noted that "it will of course be important to seek additional data on this point." We should like to offer further data and to test Knox’s on C.N.S.

malformations in

we

terms

hypothesis. To improve detection of the effects of possible sequential interaction, two subgroups were analysed. Group A consisted of those patients whose condition could not readily be attributed to genetic predisposition or to simultaneous interaction between twins (i.e., firstborn patients, and non-firstborn, nontwin patients with unremarkable family history, no older twin sibs, and no older sibs affected with the same or similar condition as that of the patient). Group B is a subgroup of A and consisted of those patients who were not firstborn, so as to allow study of the differences between the i.p. interval and other birth interval. We calculated the intervals between sibs not only in the spina-bifida group (none of our propositi had anencephaly) but also in the cerebral dysgenesis, hydrocephaly, and microcephaly groups, and determined the sex ratio of the i.p. sib in each group. In no group was the mean interval between the i.p. sib and the propositus reduced significantly from the mean of all other intervals: in fact, in cerebral dysgenesis males it was significantly increased in the total group (t=2.06, p<0.05, D.F.=34) and in subgroup A (t=2.45, p<0.05, D.F.=22). The second observation refers to the relationship between the i.P. sex (M/F) ratio and the sex of the patient. According to the genetic/interaction hypothesis of Knox the i.p. sex ratio preceding female patients under one set of assumptions should be 5/1-9/1 and that preceding male patients should be 2/1. Under slightly different assumptions, Knox concluded that the sex ratio of sibs preceding an affected female ought to be 3-6 times that preceding an affected male. Indeed, unpublished data made available to Knox by Record and McKeown showed a considerable excess of males (95/60) in i.p. sibs of affected females, a finding repeated, less strongly (63/55) in i.p. sibs of affected males. In all of our groups the i.p. sex ratio preceding females is higher than the i.p. sex ratio preceding males; in the spina-bifida group it is 6-8 times higher. Thus our data fit the second but not the first of the two criteria of Knox’s revised hypothesis. We think that on the whole our data lend greater support to James4’and Elwood6 who proposed that spina bifida is associated with infertility. The highest incidence of twinning was in the microcephaly group which is the only group in which the i.p. interval was not greater than the other previous and immediately subsequent intervals. But even in the microcephaly group the affected males have an increased i.p. interval, and all the twins in that group are female. Twinning, especially in case of prenatal death of one of the twins, may be causally(?) or pathogenetically related to the c.N.s. defects of the liveborn twin, and relative infertility may be associated with the other forms Durkin, M. V., Kaveggia, E. G., Pendleton, E., Opitz, J. M. Lancet, 1974 ii, 1389. 2. Knox, E. G. Br. J. prev. soc. Med. 1974, 28, 73. 3. Record, M. G., McKeown, T. Br. J. soc. Med. 1950, 4, 26. 4. James, W. H. Lancet, 1973, ii, 916. 5. James, W. H. ibid. 1974, i, 1353. 6. Elwood,J. M. ibid. p. 31. 1.

ofc.N.s. defect. Artificially stimulated ovulation, which is associated with both infertility and an increased incidence of multiple births, could thus be associated with an increased incidence ofc.N.s. defects for two different reasons. This work was supported by U.S. Public Health Service grant GM20130 from the National Institute of General Medical Sciences. Wisconsin Clinical Genetics Center, Departments of Medical Genetics and Pediatrics, University of Wisconsin Center for Health Sciences and Medical School, and Central Wisconsin Colony and Training School, Madison, Wisconsin 53706, U.S.A.

M. V. DURKIN E. G. KAVEGGIA E. PENDLETON J. M. OPITZ

FACTOR-VIII INHIBITOR BYPASSING ACTIVITY et al.l on the use of fraction in the treatment of a haemophiliac with factor-vm inhibitors is the latest in a series of such reports. The substances used are thought to bypass the factor-vm stage of the clotting cascade, and include, as well fraction F.E.I.B.A., "activated" factor-ix concentrates,2-4 unactivated factor-ix concentrates,’ and "fraction R".6 This treatment has not been uniformly successful, and we are prompted to report our own experience. A 46-year-old haemophiliac (0% factor-vm activity without inhibitors), developed inhibitors 3 days after operation for plating a fractured shaft of femur. This was associated with massive bleeding around the operation site unresponsive to factor vm replacement therapy. He was given factor-ix preparations (Oxford type DE1 and ’Proplex’ Hyland), for the next 5 days and on the 8th postoperative day, when the inhibitor level had reached 40 (new units), he was given fraction F.E.I.B.A. (kindly donated by Immuno AG). This was initially in a dose of 30 units/kg rising over 3 days to 80 units/kg. At no time were we able to show any shortening of the whole-blood clotting-time or the partial thromboplastin-time by any of these agents, although the prothrombin-time was shortened by about 2 s after infusions of F.E.I.B.A. We concluded that there had been some activation of coagulation by this substance, because samples of citrate plasma taken at this time and stored frozen were later found to be clotted. More importantly, however, there was no obvious cessation of bleeding. Swelling of the thigh and pain at the fracture site persisted, and superficial oozing (e.g., from stitch holes) was not affected. Although English et al. are to be congratulated on the successful outcome in their patient, the suggestion that it was due to fraction F.E.I.B.A. should be viewed with caution. The fact that this substance was given for 7 days before bleeding stopped does not attest to its being the effective haemostatic agent. Correction of abnormal clotting tests, while heartening, is not necessarily associated with clinical haemostasis. Our own experience shows that even this effect is unpredictable. That bleeding did eventually stop may have been fortuitous. Massive platelet transfusions have also been used to treat haemophiliacs with inhibitorsand tranexamic acid has a wellknown action in reducing blood-loss in haemophiliacs after certain operations. Any of these factors could have helped to produce haemostasis. English et al. state that there were no side-effects, but the fall in platelet-count is disquieting. Fraction F.E.I.B.A. and similar agents probably contain activated clotting factors, and some at least carry the risk of producing thrombembolism or disseminated intravascular coagulation, with worsening of an already severe haemostatic defect. There is also evidence that they can stimulate further the production of factor-vm inhibi-

SiR,—The report by English

F.E.I.B.A.

tors.5 1. English, P. J., Sheppard, E. M., Wensley, R. T. Lancet, 1976, i, 1299. 2. Kurczynski, E. M., Penner, J. A. New Engl. J. Med 1974, 291, 164. 3. Sultan, Y., Brouet, J. C., Debre, P. ibid. p. 1087. 4. Abildgaard, C. F., Britton, M., Roberts, R. Blood, 1974, 44, 933. 5. Allain, J. P., Kriegar, G. R. Lancet, 1975, ii, 1203. 6. Bloom, A. L., Hutton, R. D. ibid. 1975, ii, 369. 7. Kasper, C. K. New Engl. Med. J. 1973, 289, 160.

44 If the

While this is potentially a most important development, and trial of these agents in the treatment of severe, established bleeding is clearly justified, we feel that they should not be used for trivial bleeding or to cover elective surgery until they have been further evaluated. It is therefore important that both successful and unsuccessful results of treatment should be reported, and experience in the use of these agents collected and collated as quickly as possible.

of nutritional ansemia is not aimed at to normal but at the eradication of resultant ill-health, there is no reason why in-vitro tests of cell-mediated immunity should alter the policy in either direction. These tests are, of course, of importance in trying to define the nature of an observed immune deficit.

Hæmatology Department, General Hospital, Birmingham B4 6NH

treatment

returning haemoglobin levels

a

Department of Medicine, Guy’s Hospital Medical School, London SE1 9RT

N. G. P. SLATER

ANDREW POLLOCK M. J. LEWIS K-CELL FUNCTION IN PATIENTS WITH CHRONIC AGGRESSIVE HEPATITIS

LYMPHOCYTE-COUNT IN CHILDREN TREATED WITH PHENYTOIN StR,—Brandt and Nilsson’s report of subnormal lymphocyte-counts in adult patients treated with phenytoin’ prompted us to do similar survey in epileptic children. The number of peripheral-blood lymphocytes was calculated from white-blood-cell and differential counts in 58 healthy controls aged 5-14 and in 78 children aged 5-15 on treatment with anticonvulsants including phenytoin. The median lym-’ phocyte-count was 2.6x 109/1 in the controls and 2.7x 109/1 in the patients (no significant difference). When 17 healthy children and 20 patients all aged 5-7 were studied the median lymphocyte-count in controls was 2·9x109/1 and that in patients 3.5 x 109/1, indicating a significant increase in the patients (p<0.05). The number of the patients under the treatment for less than one year, for 1-5 years, and for more than 5 years were 13, 44, and 21 and their median lymphocytecounts were 2-8, 2.7, and 2.7 x 109/1, respectively. These results suggested that, in contrast to the observation of Brandt and Nilsson,’ phenytoin treatment may lead to lymphocytosis rather than lymphocytopenia, at least in younger children. The disagreement between our findings and those of Brandt and Nilsson may be due to the age difference and/or longer duration of the treatment in their cases_(no data on duration was given in their report). Brandt and Nilsson suspected that the subnormal lymphocyte population may have some bearing on the increased risk of malignant lymphoma. Since no correlation between age and lymphadenopathy has been found in patients taking hydantoin drags,2 our findings do not argue against the suggestion that treated children be examined periodically for lymphadenopathy.3

Department of Pædiatrics, Kumamoto University Medical School, Kumamoto City 860 Japan

my opinion Miller and Dwyer’s criticism’ of the Cochrane et al. was not justified, and discussion of paper by the kind of cell responsible for the effector activity reported on by Cochrane et al.2 seems to introduce an element of confusion about the nature of effector cell involved in antibody-dependent cellular cytotoxicity (.n.c.c.) (1) Cochrane et al. admit that the exact nature of the killer cell in their system has not been definitely established, and one of the possible effector cells could be macrophages. Miller and Dwyer’s suggestion that macrophages could be the killer cells does not introduce anything new. (2) In view of the fact that the nature of K cells is still not exactly known and seems to be rather heterogeneous3 I think that to use the term K cell in an operational meaning of non-immune cell capable of killing antibody-sensitised target cell is justified. This is especially true when T cells are mostly efiminated, as in Cochrane’s system. (3) Cochrane et al. did not show that only complement (C’)-receptor positive cells were functioning as effectors. At least a proportion of the effector cells seemed to belong to (C’-receptor-positive cell category, but this does not mean that these cells were the exclusive effector cells as Miller and Dwyer

SiR,—In

’

A. HIGASHI T. IKEDA I. ADABOSHI S. KARASHIMA T. MIIKE I. MATSUDA

ANÆMIA AND IMMUNE RESPONSE

SIR,-Dr Srikantia and his colleagues4 have studied a population defined by one laboratory abnormality (low haemoglobin) and correlated this with other laboratory abnormalities (T-cell rosettes, phytohaemagglutinin response, and leucocyte bactericidal activity). Their results are convincing, but do not justify a claim of public-health importance, since the laboratory evidence of "depressed immune response" was not related to any excess of clinical infection in the group. Indeed, this was specifically excluded by the design of the study. 1. Brandt, L., Nilsson, P. Lancet, 1976, i, 308. 2. Anthony, J. J. Archs Neurol., Chicago, 1970, 22, 450. 3. Li, F. P., Willard, D. R., Goodman, R., Vawter, G. Cancer, 1975, 36, 1359. 4. Srikantia, S. G., Prasad, J. S., Bhaskaram, C., Krishnamachari, K. A. V. R. Lancet, 1976, i, 1307.

imply. (4) I doubt if one can categorically exclude the antibody-dependent character of cellular cytotoxicity (as has been done by Miller and Dwyer) in view of the findings that A.D.C.C. may be a very sensitive system and that even lymphocyte-dependent antibody titres in range of 10-’z may be sometimes sufficient to exert a cytotoxic effect, and this LD antibody could be adsorbed to effector cells in vivo,4 as was pointed out by seem to

Cochrane et al. (5) There are references suggesting the presence of C’-receptor(s) on K cells.3 (6) The question whether macrophages could act as effector cells in Cochrane’s system remains open. Studies of cell populations devoid of adherent and phagocytic cells (e.g., nylonprocessed peripheral-blood lymphocytes) in the same system could throw some additional light on the nature of the effector cell involved. Binding of aggregated IgG may not be specific for Fc receptor.5 In conclusion in my opinion there is no reason for criticism of the challenging paper by Cochrane et al. More work has to be done to establish precisely what kind of cell or cells is the most important effector in A.D.C.C. in patients with chronic

aggressive hepatitis. Department of Surgery, University of California, Los Angeles, California 90024, U.S.A. * Present address: 90405. 1. 2.

STANISLAW M. MIKULSKI*

c/o Mikulski, 22 Village Park, Santa Monica, California

Miller, D. J., Dwyer, J. M. Lancet, 1976, i, 909. Cochrane, A. M. G., Moussouros, A., Thomson, A. D., Eddleston, A. L. W F., Williams. R. ibid. p.441. 3. Perlmann, P., MacLennan, I. C. M. Progr. Immun. II, 1974, 3, 347. 4. Perlmann, P., Perlmann, H., Wigzell, H. Transplant. Rev. 1972, 13, 91. 5. Frøland, S. S., Natvig, J. B., Michaelson, T. E. Scand. J. Immun. 1974 3, 375.