FETAL INTERACTIONS AND THE IMMUNE RESPONSE

133 2nd meiotic non-disjunction of the marked chromosome, because such an error leads uniquely to the child having two marked chromosomes. The other possibilities, where the child has one marked chromosome, or none, can arise by more than one class of non-disjunctional error, and thus it is not possible to deduce the error from the child’s complement. There are a number of reported cases of women with a Gph- chromosome giving birth to mongol offspring with one or no Gph- chromosome, 13, 14 but it is not possible to deduce anything about the origin of the extra chromosome ; one cannot even exclude 2nd meiotic non-disjunction in the mother in these cases, since it is not known whether the Gph- chromosome is a 21 or a 22. It must also be remembered that a Gph- chromosome is structurally abnormal, and this could affect meiosis, perhaps leading to a higher incidence of 2nd meiotic non-disjunction than usual. Trisomy with two Gph- chromosomes could also arise by mitotic non-disjunction in the very early normal zygote. Thus, if we exclude these latter two cases, we have 18 cases of standard trisomy 21, of which five have been shown to be due to maternal first meiotic nondisjunction. Licnerski and Lindsten give no information about their five other cases, but maternal second meiotic non-disjunction could be excluded in five cases of the present series, and second meiotic nondisjunction in either parent could be ruled out in one. The average maternal age for the four cases in this series in which the error was shown to be maternal is 35 years (the single case of Licnerski and Lindsten was aged 40), while that of those cases where paternal error could not be excluded was 30 years. The maternal-age effect on the incidence of Down’s syndrome has led to the idea that non-disjunction in the mother is the most likely cause of trisomy 21, and the data presented here indicate that first meiosis is the most common time for that non-disjunction to occur. The importance of these findings in relation to the possible mechanisms involved in the nondisjunction will be considered elsewhere. I should like to thank the staff of the Medical Research Council’s Clinical and Population Cytogenetics Unit, especially Dr Marjorie S. Newton, and the staff of Prudhoe and Monkton Hospital, Prudhoe, Northumberland, for their help in this survey. REFERENCES

Caspersson, T., Zech, L., Johansson, C. Expl Cell Res. 1970, 60, 315. 2. O’Riordan, M. L., Robinson, J. A., Buckton, K. E., Evans, H. J. Nature, 1971, 230, 167. 3. Evans, H. J., Buckton, K. E., Sumner, A. T. Chromosoma, 1971, 1.

35, 310. Schnedl, W. Humangenetik, 1971, 12, 59. 5. Hungerford, D. A. Stain Technol. 1965, 40, 333. 6. Robinson, J. A., Buckton, K. E. Chromosoma, 1971, 35, 342. 7. Hulten, M., Lindsten, J. in Human Population Cytogenetics (edited by P. A. Jacobs, W. H. Price, and P. Law); p. 23. Edinburgh, 1970. 8. Thompson, P. E. Genetics, 1963, 48, 697. 9. Pardue, M. L., Evans, H. J., Buckland, R. A. Personal

4.

communication. 10. 11.

12. 13. 14.

Licnerski, G., Lindsten, J. Hereditas, 1972, 70, 153. de Grouchy, J. Ann. Genet. 1970, 13, 52. Juberg, R. C., Jones, B. New Engl. J. Med. 1970, 282, 292. Shaw, M. W. Cytogenetics, 1962, 1, 141. Neu, R. L., Leao, J. C., Gardner, L. I. Lancet, 1966, ii, 390.

Hypothesis MATERNAL/FETAL

INTERACTIONS AND THE IMMUNE RESPONSE

J. GILL, III Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, U.S.A. THOMAS

Experimental work has shown that the transplacental passage of antigen can either sensitise the fetus or render it partially tolerant. It is suggested that a variety of clinical observations made under physiological or pathological conditions can also be explained in terms of transplacental sensitisation of the fetus by antigen. Summary

INTRODUCTION

THE hypothesis proposed in this paper, based on experimental work, is that transplacental passage of antigen can immunise the fetus or render it partially tolerant. This hypothesis can explain some clinical observations on the altered immune capabilities of the offspring of mothers sensitised to a variety of antigens or exposed to infectious diseases during Further investigation may elucidate pregnancy. several aspects of the maternal/fetal interaction and may serve as the basis for a novel approach to the development and clinical use of vaccines. PASSIVE TRANSFER OF IMMUNITY

Passive immunity is transmitted to the young in the form of humoral antibodies 1- either via the maternal circulation before birth or via the milk immediately after birth, and the relative contribution of each route varies from species to species. Ruminants, horses, and pigs derive their maternal antibody from the In colostrum during the early postnatal period. in of transfer the man, contrast, passive immunity

monkey, rabbits, and guineapigs is almost exclusively prenatal. In the rabbit and guineapig transfer is by way of the fetal yolk sac, whereas in man and monkey the yolk sac is only a rudimentary organ and significant transmission of passive immunity does not occur by this route. In these species the maternal antibody is secreted into the embryonic fluid and then absorbed by the fetal intestine or directly transferred across the placenta. The transmission of passive immunity in the dog, cat, rat, and mouse is intermediate between the two groups discussed above: some prenatal transfer of antibodies occurs by way of the embryonic fluid and the yolk sac, but postnatal absorption from the colostrum accounts for most of the transfer. The passively transferred antibody plays a significant role in protecting the newborn against infectious agents during the early weeks of life and may affect its ability to respond to antigenic stimulation during this period. ACTIVE ALTERATION OF FETAL IMMUNE RESPONSE

Experimental

1.4-10 and clinical 11 studies that the shown mammalian fetus can mount an

have

adap-

134

tive immune response and that the ability to

various

antigens develops sequentially.

to

respond There is

no direct relation between the acquisition of immune responsiveness and the state of development of the lymphoid tissue. I and my colleagues 12-H have shown that the fetus can be actively immunised by the transplacental passage of antigen. Immunisation of a genetically poorly responding strain of rats with an aggregated antigen sensitised their offspring to the antigen: the fetuses, placentas, and neonates contained specific antibody-forming cells and the offspring showed an enhanced capability of forming specific antibody after immunisation with the antigen. The first and second litters in the F1 generation and the F2 generation showed the enhanced immune response. The aggregated antigen was transmitted from the immunised female to her offspring, and it localised mainly in the bone-marrow. The total duration over which the effect lasted correlated with the solubility of the aggregate used: the longer the aggregate persisted, the longer the effect lasted. Immunisation of a genetically highly responding strain of rats under the same conditions induced partial tolerance in the offspring. H These effects could not be induced by large doses of antigen alone. We believe that the role of aggregation is to protect the antigen from degradation and to release it slowly over a long period of time. Preliminary data 14 indicate that small, soluble particles of aggregate cross the placenta into the fetus.

apparently

mouse placental cells can transform into erythrocytic and lymphocytic cells both morphologically and functionally.Z1 Other studies 22-25 also indicate that some lymphocytes pass from the mother to the fetus, but they provide no evidence that these cells persist or that they play any physiological role in the offspring. Under certain unique circumstances, however, cells can cross the placenta after immunisation of the mother with a skin-graft. 26Thus, the question of the transplacental passage of lymphocytes has

not

been settled.

Since mammalian fetuses

can

be cultured

vitro,2’ the passage of molecules and cells across the placenta can now be investigated in laboratory animals in

under

more

controlled conditions.

occurring in utero are also involved in the pathogenesis of immunologically mediated diseases. The development of erythroblastosis fetalis due to the passage of anti-Rh antibodies across the placenta is well known. In five species 9f animals, graft-versushost reactions can be induced in the fetus by a skingraft from the paternal to the maternal animal at a well-defined time before mating.26 Transplacental infection of mice with the lymphocytic-choriomeningitis virus and the subsequent passage of antibody in the milk of the infected mother can cause antibodyantigen complex disease in the offspring. 28" Finally, preliminary studies in our laboratory 14 suggest that the transplacental passage of aggregated antigens may also be implicated in the induction of immunologically Events

mediated diseases. CLINICAL OBSERVATIONS

Similar

findings have been reported in two other systems.

First, rats born of mothers immunised with Plasmodium berghei 15 have significantly higher levels of immunity to P. berghei after immunisation with a non-living antigen than either their unvaccinated litter-mates or vaccinated rats born of non-immune mothers. Secondly, studies on the offspring of mice rendered tolerant to pneumococcal polysaccharide 16,17 showed that, during the first month of life, these mice were susceptible to immunological stimulation or paralysis by smaller amounts of antigen than were the offspring of normal parents. The findings in both of these experiments are consistent with my hypothesis. The offspring of the immunised rats could have been sensitised by the transplacental passage of antigens from P. berghei. Pneumococcal polysaccharide could have passed into the fetus and altered the size of the cell population capable of reacting with it; hence, the amount of antigen needed for stimulation or for paralysis would be smaller. This postulate is further strengthened by the finding that after immunisation with pneumococcal polysaccharide there were less plaque-forming cells in the spleens of offspring from tolerant mothers than in the spleens of offspring from unimmunised mothers. The possibility that primed maternal immunocompetent cells might cross the placenta to colonise the fetus must be explored further in order to ascertain whether they also might affect the immune response of the fetus. So far, studies on the passage of cells across the placenta have led to contradictory results. Experiments purporting to show the transplacental passage of maternal cells ’ 3 used CBA mice carrying the 7" 6 T chromosome marker and CFW mice. However, other workers 19 could not reproduce these results, indicating that no significant number of maternal lymphocytes crossed the placenta. Some of the differences may be related to a peculiarity in the placentas of CFW mice and to the difficulties in clearly identifying the 7 T 6 chromosome marker in CBA mice. 20 In addition,

can be explained alteration in the fetal immune response due to the transplacental passage of antigens. First, lymphoid sensitisation shown by mothers under both physiological and pathological conditions was also shown by their children. Normal mothers who were sensitive to purified protein derivative (P.P.D.) had children whose cells reacted with P.P.D., and mothers with neoplasia (Hodgkin’s disease, brain tumours) or with sarcoidosis had children whose lymphocytes were sensitive to the antigens of these diseases. 29 Other studies 30,31have shown a frequency of about 30% for in-vitro lymphocyte responsiveness to various ubiquitous antigens in cord-blood cultures, and chromosomal studies showed that the lymphocytes undergoing transformation were those of the fetus and were not contaminating maternal cells. Secondly, a 10 of Eskimo children after intrauterine years study to evidence that their mumps produced exposure sensitisation to the mumps antigen occurred without subsequent exposure to mumps.32,33 The mothers of all twelve children studied had serological evidence of exposure to the mumps virus, and their children all had mumps-positive skin-tests but no evidence of mumps neutralising antibody; hence, the immunological response to in-utero exposure to the mumps virus was primarily cellular. Most of the children conceived and born after the epidemic did not have any evidence of sensitisation to the mumps virus. Finally, the passage of hepatitis-associated antigen from mothers with hepatitis to their fetuses has been demonstrated.34 Of fifty-six mothers who had acute viral hepatitis during pregnancy, or within 6 months

A

by

variety of clinical observations

an

135 of delivery, eighteen had children who for the hepatitis-associated antigen.

were

positive

MAGNESIUM DEFICIENCY: A CAUSE OF REVERSIBLE RENAL FAILURE ROBERT WHANG

MICHAEL P. RYAN JERRY K. AIKAWA

CONCLUSION

Exposure to various antigens and to infectious agents during pregnancy caused the development of specific immunological sensitivity in the fetus without any subsequent exposure after birth. The transplacental passage of antigen seems to be the most reasonable cause of the fetal sensitisation and the subsequent alteration in its immunological capabilities. If the mechanism by which this event occurs can be more clearly defined by experimental work and documented more fully by prospective clinical studies, methods of immunological engineering " 35 can be developed by which manipulation of the maternal environment during the development of the fetus (e.g., with a longacting vaccine) could afford the offspring an enhanced immune response against infectious agents in the postnatal period or against teratogenic and oncogenic "

viruses in

utero.

The work in my laboratory was supported by grants from the National Institutes of Health (AI-10611 and GM-00135) and the Easter Seals Research Foundation (R-7038).

Departments of Medicine,

University of Connecticut School of Medicine and University of Colorado School of Medicine, and Veterans Administration Hospital, Newington, Connecticut, U.S.A. The presence of

myocardial potassium deficiency, fibrosis, necrosis, and calcification in the magnesium-deficient rat, together with azotæmia which is rapidly reversible with magnesium repletion, suggests the hypothesis that deficiency of magnesium is a cause of reversible, prerenal azotæmia, the mechanism of which is hæmodynamic rather than morphological. Clinical conditions in which this hypothesis may apply include protein-calorie malnutrition, alcoholic and cobalt cardiomyopathy, and congestive heart-failure treated Sum ary

with diuretics.

REFERENCES

9.

Brambell, F. W. R. The Transmission of Passive Immunity from Mother to Young. Amsterdam, 1970. Solomon, J. B. Fetal and Neonatal Immunology. Amsterdam, 1971. Gitlin, D. in Immunologic Incompetence (edited by B. J. Kagan and E. R. Stiehm); p. 3. Chicago, 1971. Sterzl, J., Silverstein, A. M. Adv. Immun. 1967, 6, 337. Silverstein, A. M., Prendergast, R. A. in Developmental Aspects of Antibody Formation and Structure (edited by J. Sterzl and I. Riha); p. 69. Prague, 1970. Richardson, M., Connor, G. H., Beck, C. C., Clark, D. T. Immunology, 1971, 21, 795. Richardson, M., Connor, G. H. Infect. Immun. 1972, 5, 454. Shifrine, M., Smith, J. B., Bulgin, M. S., Bryant, B. J., Zee, Y.-C., Osborn, B. I. J. Immun. 1971, 107, 965. Dennis, R. A., Jacoby, R. O., Griesmen, R. A. Am. J. vet. Res. 1969,

10.

30, 1503, 1511, 1517. Rowlands, D. T., Blakeslee, D., Lin, H.-H. J. Immun. 1972, 108,

11. 12. 13.

Silverstein, A. M., Lukes, R. J. Lab. Invest. 1962, 11, 918. Gill, T. J., III, Kunz, H. W. J. Immun. 1971, 106, 274. Gill, T. J., III, Kunz, H. W., Bernard, C. F. Science, 1971, 172,

1. 2.

3. 4. 5.

6. 7. 8.

941.

1346. 14. Gill, T. J., III, Kunz, H. W. Unpublished. 15. Desowitz, R. S. Science, 1971, 172, 1151. 16. Kerman, R., Segre, D., Myers, W. L. J. Immun. 1970, 104, 656. 17. Kerman, R., Segre, D. ibid. p. 1262. 18. Tuffrey, M., Bishun, N. P., Barnes, R. D. Nature, 1969, 221, 701, 1029. 19. Billington, W. D., Kirby, D. R. S., Owen, J. J. T., Ritter, M. A., Burtonshaw, M. D., Evans, E. P., Ford, C. E., Gould, I. K., McLaren, A. ibid. 1969, 224, 704. 20. ibid. p. 747. 21. Dancis, J., Jansen, V., Gorstein, F., Douglas, G. W. Am. J. Obstet. 22. 23. 24.

Gynec. 1968, 100, 1110. Desai, R. G., Creger, W. P. Blood, 1963, 21, 665. Papiernik, M., Nezelof, C. Archs fr. Pédiat. 1970, 27, 777. Walknowska, J., Conte, F. A., Grambach, M. M. Lancet, 1969, i, 1119.

25. 26. 27. 28. 29. 30. 31.

Mohr, J. A. ibid. 1972, i, 688. Beer, A. E., Billingham, R. E. Adv. Immun. 1972, 14, 1. New, D. A. T. Adv. Biosc. 1970, 6, 367. Oldstone, M. B. A., Dixon, F. J. J. exp. Med. 1972, 135, 827. Field, E. J., Caspary, E. A. Lancet, 1971, ii, 337. Leiken, S., Oppenheim, J. J. ibid. p. 876. Leiken, S., Whang-Peng, J., Oppenheim, J. J. in Proceedings of the Fifth Leucocyte Culture Conference; p. 389. New York, 1970.

32.

Aase, J. M., Noven, G. R., Reddy, D. V., St. Geme, J. W. New Engl. J. Med. 1972, 286, 1379. 33. Silverstein, A. M. ibid. p. 1413. 34. Schweitzer, I. L., Wing, A., McPeak, A., Spears, R. L. J. Am. med. Ass. 1972, 220, 1092. 35. Gill, T. J., III. Milit. Med. (in the press).

IN the rat, experimental magnesium deficiency is associated with the following biochemical abnormalities : (1) hypercalcxmia, (2) hypomagnesaemia, (3) azotxmia, and (4) a small but statistically significant deficit in muscle-potassium despite provision of potassium.1 These biochemical abnormalities are accompanied by significant renal morphological changes, including microliths in the ascending limb of Henle’s loop which slowly grow by accretion and eventually, by virtue of their size and pressure exerted on the tubular structure, disruption of the tubular epithelium with interstitial fibrosis.2 3 These observations from microdissection studies are associated with gross nephrocalcinosis. The precise genesis of the renal morphological changes is unclear, but might be related to enhanced alkalinity in the ascending limb of Henle’s loop. The calcium content of the magnesiumdeficient kidney is significantly diminished during prolonged repletion with magnesium. The azotaemia accompanying magnesium deficiency is reversible as early as 7 days after initiation of magnesium repletion and has been ascribed previously to the renal morphological abnormalities.4 Evidence from other sources of involvement of the myocardium by necrotic, fibrotic, and infiltrative lesions associated with the magnesium-deficient state in rats suggests an alternative hypothesis for the azotaemia

accompanying experimental magnesium depletion-namely, a prerenal component on the basis

of decreased cardiac function. Indirect evidence to support this hypothesis comes from the work of Barger and Herd.° Their data clearly indicate that in the presence of overt heart-failure hypoperfusion of the renal cortex occurs. As a consequence of diminished renal perfusion there is a diminution in both glomerular filtration-rate and renal plasma-flow, with the filtration fraction increasing beyond the usual 0-2. Clinical data support the view that azotxmia