748
`
`10. Eden AN, Kaufman A, Yu R. Corticosteroids and croup: controlled
`double-blind study. JAMA 1967; 200: 403-04.
`11. Koren G, Frand M, Barzilay Z, MacLeod SM. Corticosteroid treatment
`of laryngotracheitis v spasmodic croup in children. Am J Dis Child
`1983; 137: 941-44.
`12. Super DM, Cartelli NA, Brooks LJ, Lembo RM, Kumar ML. A
`prospective randomised double-blind study to evaluate the effect of
`dexamethasone in acute laryngotracheitis. J Pediatr 1989; 115: 323-29.
`13. Phelan PD, Landau LI, Olinsky A. Respiratory illness in children, 3rd ed.
`Oxford: Blackwell, 1990: 47-88.
`14. Tibballs J. Equipment for paediatric intensive care, 3rd ed. In: Oh TE,
`ed. Intensive care manual. Sydney: Butterworth, 1990: 666-72.
`15. Rivera R, Tibballs J. Complications of endotracheal intubation and
`mechanical ventilation in infants and children. Crit Care Med 1992; 20:
`193-99.
`16. Freezer N, Butt W, Phelan P. Steroids in croup: do they increase the
`incidence of successful extubation? Anaesth Intens Care 1990; 18:
`224-28.
`
`17. Casagrande JT, Pike MC. An improved approximate formula for
`calculating sample sizes for comparing two binomial proportions.
`Biometrics 1978; 34: 483-86.
`18. Christensen E. Multivariate survival analysis using Cox’s regression
`model. Hepatology 1987; 7: 1346-58.
`19. Altman DG. Practical statistics for medical research. London: Chapman
`and Hall, 1991: 365-95.
`20. Smith DS. Corticosteroids in croup: a chink in the ivory tower? J Pediatr
`1989; 115: 256-57.
`21. Narcy P. Corticotherapie et laryngite aigue sous-glottique. Arch Fr
`Pediatr 1991; 48: 389-90.
`22. Tunnessen WW, Feinstein AR. The steroid-croup controversy: an
`analytic review of methodologic problems. J Pediatr 1980; 96: 751-56.
`23. Kairys SW, Olmstead EM, O’Connor GT. Steroid treatment in
`laryngotracheitis: a meta-analysis of the evidence from randomised
`trials. Pediatrics 1989; 83: 683-93.
`24. Kuusela AL, Vesikari T. A randomised double-blind placebo-controlled
`trial of dexamethasone and racemic epinephrine in the treatment of
`croup. Acta Paediatr Scand 1988; 77: 99-104.
`
`Humanised monoclonal antibody therapy for
`rheumatoid arthritis
`
`Monoclonal antibodies that target T cells have
`shown some benefit in rheumatoid arthritis although
`responses have not been long lasting. This is partly
`due to insufficient therapy consequent upon
`antibody immunogenicity. Use of humanised
`antibodies, which are expected to be less foreign to
`man than conventional rodent antibodies, might
`overcome this problem. We therefore assessed in a
`phase 1 open study the potential of a "lymphocyte
`depleting" regimen of the humanised monoclonal
`antibody CAMPATH-1H in 8 patients with
`refractory rheumatoid arthritis.
`Apart from symptoms associated with first
`infusions of antibody, adverse effects were
`negligible. Significant clinical benefit was seen in 7
`patients, lasting for eight months in 1. After one
`course of therapy, there was no measurable
`antiglobulin response, although 3 out of 4 patients
`have become sensitised on retreatment.
`Humanisation reduces the immunogenicity of
`rodent antibodies but anti-idiotype responses may
`still be seen on repeated therapy, even in patients
`sharing immunoglobulin allotype with the
`humanised antibody.
`
`Introduction
`Monoclonal antibodies (mAbs) are being studied for
`treatment of autoimmune and inflammatory diseases.!
`Rheumatoid arthritis is a common, progressive, crippling
`disease; because of its association with HLA, and the
`response to therapies such as thoracic duct drainage, total
`lymphoid irradiation, and cyclosporin, there is compelling
`evidence that T cells have a crucial role in its pathogenesis.
`Although mAbs that target T cells have shown benefit in
`rheumatoid arthritis, responses have been of limited
`duration. Furthermore, the therapeutic "window" within
`which antibodies could be used has been narrow because of
`the antiglobulin response against the therapeutic agent.2,3
`
`To reduce to a minimum the immunogenicity of therapeutic
`antibodies, "reshaping" by genetic engineering has been
`used to convert rodent antibodies to a human form.4,5 Such
`"humanised" antibodies should appear less foreign to man
`than do conventional rodent antibodies. With existing
`techniques, however, "humanisation" leaves open the
`chance for anti-idiotypic and anti-allotypic responses. We
`have assessed the potential of humanised antibodies for
`treatment of rheumatoid arthritis.
`
`Patients and methods
`
`Patients
`
`Characteristics of the 8 patients are shown in table i. They
`fulfilled the American Rheumatism Association criteria for
`rheumatoid arthritis and had active disease as defmed by three of the
`10, early morning
`following four criteria: Ritchie articular index >
`stiffness > 45 min, erythrocyte sedimentation rate (ESR) > 30 mm
`10. 7 patients were seropositive. Their
`per hour, joint score >
`disease had proved unresponsive to a current and at least one other
`second-line agents, and these had been stopped at least four weeks
`before administration of CAMPATH-1H. Patients were allowed to
`continue with non-steroidal anti-inflammatory drugs (NSAIDs)
`and an existing dose of prednisolone (up to 20 mg daily). They were
`otherwise healthy, and had normal renal and hepatic function.
`Approval of the local ethics committee and informed consent of the
`patients were obtained.
`
`Treatment
`
`CA MPA TH-1 1 H--CAMPATH- 1 H is a human IgG1 mAb that is
`specific for the glycoprotein CDw52, an antigen present on all
`lymphocytes and some monocytes.6 This mAb was derived by
`humanisation of the rodent antibody CAMPATH-lG.4
`Therapeutic-grade antibody was produced in Chinese hamster
`ovary cells grown in a hollow-fibre continuous culture system
`(Acusyst-Junior, Endotronics Inc, Minneapolis, MN, USA) and
`was purified on protein A. The antibody was formulated in
`
`ADDRESSES Cambridge University Department of Pathology
`(Immunology Division), Tennis Court Road, Cambridge CB2
`1QP, UK (J D. Isaacs, MRCP, G Hale, PhD, S P Cobbold, PhD, H
`Waldmann, MRCP), and Departments of Rheumatology (R. A.
`Watts, MRCP, B. L. Hazleman, FRCP), and Clinical Immunology
`(M T Keogan, MRCPI) Correspondence to Dr John D. Isaacs
`
`Pfizer v. Genentech
`IPR201(cid:26)-01488
`Genentech Exhibit 202(cid:24)
`
`

`

`749
`
`*Maximum attainable Ritchie and joint scores were 78 and 26, respectively.
`tSum of 4 scores (max=100 each) measured on a 10 cm visual analogue scale representing night pain, rest pain, general wellbeing, and functional ability
`ESR=erythrocyte sedimentation rate, CRP= C-reactive protein.
`G =gold, P=pemcillamme, M = methotrexate, S=su!phasaiaz!ne. ylFN = y-interferon, A=azathioprine, CyA=cyctospor!n, C = cyclophosphamide
`
`phosphate-buffered saline and after sterility and endotoxin checks it
`was stored at - 30°C before administration. Before infusion it was
`diluted in 100 ml (first treatment) or 500 ml (retreatment) normal
`saline.
`Therapeutic regimerr-Patients were admitted to hospital for
`antibody therapy. CAMPATH-1H was given by intravenous
`infusion over 2-4 hours, during which vital signs were recorded
`every 15 min. A course of therapy lasted for 10 days, and consisted
`of 4 mg antibody daily for 5 days followed by 8 mg antibody daily for
`5 days. Between daily infusions, patients were fully mobile but did
`not receive physiotherapy. A second course of therapy consisted of
`40 mg antibody daily for 5 days.
`
`Assessment
`Ritchie articular index and joint score were assessed immediately
`before treatment, and daily during treatment. Duration of morning
`stiffness, patient’s global assessment (sum of 4 scores representing
`night pain, rest pain, general wellbeing, and functional ability, each
`measured on a visual analogue scale), joint thermography, ESR,
`C-reactive protein, and full blood count with differential white-cell
`count were also recorded. A similar assessment was done every week
`after therapy for 1 month, and then every month. Patients were
`judged to have relapsed if a further second-line agent, an increase in
`prednisolone dose, or a second course of CAMPATH-1H was
`administered to control recurrent symptoms.
`Lymphocytes andallotyping-The following stains were used to
`determine subsets of peripheral blood lymphocytes: CD4 = CD4
`CD8-, and CD8CD8’ CD4- (Simultest 349508, Becton
`Dickinson, USA); natural killer (NK) cells = CD 16 - /CD56 - CD3-
`(Simultest 349515); B-cells=CD19- (Dako R808, High
`Wycombe, Bucks, UK). The immunoglobulin allotype of each
`patient was determined in a haemaglutination inhibition assay with
`a commercial kit (Central Laboratory of the Netherlands Red Cross
`Blood Transfusion Service, Amsterdam).
`
`CD4 (0 53 2 20x 109 /1)
`CDB (0 30 - 144x109/1) /I)
`[]B B
`(011 - 0 60x109/1)
`- NK (0 12-0 88x109/1)
`
`Days from start of therapy
`Fig 1-Lymphocyte subset counts.
`n refers to no of patients analysed at each time point (subset data could
`not be obtained when total lymphocyte count < 0 4 x 10’/1, and
`pre-treatment values not available for patient E) Horizontal line represents
`lower limit of normal range for total lymphocyte count
`
`CAMPATH-1H-Serum CAMPATH-1H concentrations were
`measured by immunofluorescence with human peripheral blood
`lymphocytes. 5 x 105 cells (suspended in wash buffer [phosphate
`buffered saline containing 0-2% bovine serum albumin and 0-01%
`azide]) were incubated for 1 h on ice with an equal volume of patient
`serum (heat-inactivated at 56&deg;C for 30 min). After extensive
`washing, bound CAMPATH-1H was sought with fluorescein-
`IgG1
`isothiocyanate-conjugated
`anti-human
`monoclonal
`immunoglobulin (Sigma F0767 [Poole, Dorset, UK] diluted 1/100
`in wash buffer containing 10% heat-inactivated normal rabbit
`serum). Cells were fixed, and relative fluorescence intensity was
`measured by means of a FACScan (Becton Dickinson). A standard
`curve of median fluorescence values obtained with known
`concentrations of CAMPATH-1H (diluted in heat-inactivated
`normal human serum) was used to determine absolute
`concentrations in the sera. The sensitivity of the assay was between
`40 and 100 ng/ml.
`Antiglobulin response--Two assays were used to assess
`antiglobulin reactivity in patients’ sera. Serum samples from all
`patients were tested in a double-capture enzyme-linked
`immunosorbent asssay (ELISA).’ This test is a sensitive and
`specific assay for detecting antiglobulins able to bind monovalently
`to CAMPATH-1H, thereby excluding low-affinity antiglobulins
`and rheumatoid factors; an additional advantage is that it
`discriminates between anti-idiotype, anti-isotype, and anti-allotype
`antiglobulins. This assay could detect 10 ng/ml monoclonal
`anti-CAMPATH-1 idiotypic antibody (YID 139),’ and 2 Ilg/ml
`polyclonal goat anti-human IgG (Fc-specific, Sigma 12136). Sera
`that were positive in the ELISA were further analysed with a
`functional read-out that measured their ability to block binding of
`CAMPATH-1H to the CAMPATH-1 antigen. 25 &micro;1 heat-
`inactivated serum was mixed with an equal volume of CAMPATH-
`1H (4 Ilg/ml in heat-inactivated normal human serum). 5 x 105
`peripheral blood lymphocytes were then added and bound
`CAMPATH-1 H was sought. Blocking activity was expressed as the
`serum titre that inhibited CAMPATH-1H binding by 50%. This
`was equivalent to 125 ng/ml YID 139. Whilst providing a
`functional measure of antiglobulin neutralising activity, this assay
`may not be completely specific. For example, soluble CAMPATH-
`1 antigen also inhibits in this assay (unpublished).
`Statistical analysis-Patient data were analysed with the Mann-
`Whitney U test, comparing values after treatment with those on
`day 0. Data obtained after relapse were excluded from statistical
`analysis to avoid the introduction of bias by additional therapies.
`
`Results
`
`Clinical findings
`The first infusion of antibody led to a rapid fall in total
`lymphocyte count in all patients. Lymphopenia was evident
`as early as an hour after the start of the first infusion, when
`systemic symptoms of fever (up to 40&deg;C), rigors, and nausea
`developed in all patients; hypotension developed in 1
`patient. These symptoms lasted for 2-3 hours and were
`more pronounced in patients receiving 40 mg of antibody at
`
`

`

`750
`
`TABLE II-CLINICAL OUTCOME AFTER A SINGLE COURSE OF TREATMENT
`
`Values are median (range) for each mdex at each time point *Number in square brackets refers to patients remaining in study at each time point
`tsignificant at p<0 05 by Mann-Whitney U test
`
`I
`
`I
`
`I
`
`I
`
`I
`
`I
`
`TABLE III-SEROLOGICAL AND CLINICAL RESPONSES TO CAMPATH-1 H THERAPY
`
`*As measured by ELISA, and expressed in ng/mt equivalents of the monoclonal ant!-id!0type Y!D 13-9, which recogmsesthe CAM PATH -1 H idlotype
`tBlocking activity refers to the ability of patients’ sera to inhibit by 50% the binding of 2 pg/ml CAM PATH -1 H to antigen on PBL, this is equivalent to approximately 125 ng/ml
`of the monoclonal anti-idiotype antibody YID 13 9
`
`the start of retreatment. Lymphocyte counts remained
`suppressed for several months after therapy (fig 1). The
`latest values (normal range 1-5-4-0 x 109/1) in the first
`patients treated are 0 43 x 109/1 at 351 days (patient A),
`1-22 x 109/1 at 225 days (B), 0-48 x 109/1 at 369 days (C),
`0-79 x 109/1 at 185 days (D), and 0-22 x 109/1 at 259 days (E).
`Subset analysis showed that NK cells were spared after
`CAMPATH-1H treatment, consistent with in-vitro
`observations of the rat IgM mAb CAMPA TH -1M. B-cell
`numbers had returned to normal range by day 60. CD8
`lymphocyte numbers were approaching normal range by
`day 210, whereas CD4 cells remained suppressed at this
`time.
`In 7 patients there was an impressive, sustained response
`to therapy as shown by clinical reduction in joint swelling
`and improvement in thermography. Additionally, there
`were statistically significant improvements in Ritchie
`articular index and joint score lasting until day 125 (table n).
`There was no change in the ESR or C-reactive protein
`concentration with therapy, and no correlation between
`clinical relapse and lymphocyte count. Duration of
`remission lasted from 12 weeks to 8 months (table III). 4
`patients have now been re-treated (table III). 1 patient was
`withdrawn from therapy because of a strong first-dose
`reaction, nonetheless, his disease improved for 60 days after
`a single dose of 40 mg CAMPATH-1H. The other patients
`
`TABLE IV-IMMUNOGLOBULIN ALLOTYPES OF THE PATIENTS
`
`*Patients could not be reliably typed for G1 m 1, 2, and 17 allotypes (see text)
`
`continue to show therapeutic benefit up to 200 days after
`retreatment. In 2 of them response duration has surpassed
`that obtained with their first course of antibody treatment.
`Apart from the first-dose response (see above) and similar
`but milder symptoms after the second dose, therapy was
`Culture-negative mouth ulceration
`well
`tolerated.
`developed in the first 2 treated patients, but this was not seen
`in subsequent patients given prophylactic amphotericin and
`antibacterial mouthwashes. Mild herpes simplex mouth
`ulceration developed in patient D but responded to topical
`therapy with acyclovir.
`
`Laboratory findings
`Allotyping-The immunoglobulin allotypes are shown in
`table IV. Despite the small number of patients, these data
`accord with other published results. In particular, the Glm
`1, 2, 3, 17 allotype has been shown to be more common and
`the Glm 1, 3, 17 less common in patients with rheumatoid
`arthritis.9 CAMPATH-1H has the allotype Glm 1, 17,
`Km3.5 All our patients possessed the Km3 light-chain
`allotype but at least 2 differed in heavy-chain allotype from
`CAMPATH-1H and therefore had the potential to make an
`anti-allotype response. It was not possible to achieve a
`consistent assessment of Glm 1,2, or 17 allotype for patients
`B and F, possibly because of rheumatoid factors interfering
`with the haemagglutination inhibition assay.
`CAMPATH-1H-Trough antibody
`concentrations
`remained below 1 &micro;g/ml in all patients (fig 2) until dose
`escalation when they reached between 1 and 5 (ig/ml. The
`mean value 24 hours after the last dose of antibody was about
`2-3 &micro;g/ml. Antibody concentrations fell with a half-life of
`less than a week, so that 2 weeks after therapy, antibody was
`undetectable in all but 2 patients (F, G), in whom antibody
`concentrations were 40 ng/ml at 25 days and 80 ng/ml at 19
`days, respectively. It should be noted that about 10 &micro;g/ml of
`CAMPATH-1H is needed to saturate surface receptors
`(CDw52) on peripheral blood lymphocytes in vitro. In all
`patients completing a second course of treatment trough
`antibody values reached at least 5 j.lg/ml during therapy
`(fig 2).
`
`

`

`751
`
`increases the likelihood of an antiglobulin response to
`CAMPATH-1H, but it is now clear that even in the best
`possible situation of allotype matching, an anti-idiotype
`response may still be elicited. This finding accords with
`predictions from animal experiments. 10,111 Our data agree
`with experience of rat mAb CAMPATH-1 G treatment for
`resistant rejection in transplant recipients. 12 With an
`equivalent assay to ours, an antiglobulin response was
`detected in 11 of 14 patients, between 11 and 18 days after a
`single course of mAb therapy, even with concurrent
`immunosuppression, which generally reduces the incidence
`of antiglobulin responses. In that transplant study patients
`received 5-10 mg/day of CAMPATH-1 G for 6-10 days and
`most patients mounted a mixed (anti-isotype and anti-
`idiotype) antiglobulin response.
`The identity of the blocking activity detected in some sera
`before and after one course of treatment in our study is
`unclear; it may represent a soluble form of the CAMPATH-
`1 antigen or perhaps low affinity antiglobulins, but
`discriminating between these options is difficult in view of
`the low titres. Whatever the nature of this blocking activity,
`effective serum antibody values and a sustained therapeutic
`response were seen upon re-treatment.
`The side-effects observed in this study were acceptable.
`The first-dose response accompanied lympholysis and was
`presumably mediated by released cytokines. Similar
`symptoms are seen in patients receiving OKT3, a mAb
`directed to CD3 epsilon chain on human T cells. In that
`setting, cytokines are released as a result of T-cell activation,
`and a combination of tumour necrosis factor alpha and
`interleukin-1 can account for the clinical fmdings.13 Apart
`from occasional oral ulceration infective complications were
`not seen in our patients. This observation mirrors that in
`laboratory animals, which stay healthy despite many weeks
`of anti-T cell antibody therapy, perhaps because of normal
`of neutrophils and monocytes.
`Infective
`levels
`complications, including herpes simplex infection, have
`been reported during antibody therapy but usually in
`association with additional potent immunosuppression.14,15
`Animal experiments conducted in our own laboratories
`suggest that it may eventually be possible to control
`autoimmune states with single courses of antibody therapy
`by inducing tolerance to the putative autoantigen.16
`However, until appropriate regimens are available for
`human therapy, inflammation must be controlled by
`alternative means; antibodies seem to be the most potent
`agents available. Already they have been used to treat
`otherwise refractory cases of psoriasis t and inflammatory
`bowel disease,18 and our study extends our knowledge of
`their use in rheumatoid arthritis. Although the
`improvements we observed were generally modest, it is
`remarkable that they were obtained with such small doses of
`antibody. To maximise our chance of targeting most
`peripheral lymphocytes, we doubled the dose of
`CAMPATH-1H administered after day 5 but serum
`concentrations were still below those required to saturate
`peripheral blood lymphocytes. Future studies must take
`advantage of the potent effects of CAMPATH-1H, whilst
`investigating ways of maximising therapeutic benefit. Our
`current re-treatment protocol is designed to ask whether a
`higher dose of mAb will improve outcome, and preliminary
`data are encouraging; 2 of 3 evaluable patients have now
`achieved an increased response duration on re-treatment.
`Alternatively, additional benefit may derive from
`combination therapy. Thus sequential treatment with
`CAMPATH-1H and a CD4 mAb gave a longer-lasting
`
`Day of therapy
`Fig 2-Mean serum CAMPATH-1H concentrations during
`first course of treatment (top) and during retreatment in
`3 patients (bottom).
`Bars=SD; arrows show doses administered. *Value is 24 hours after
`last dose of antibody. t48 hours between third and fourth doses of
`antibody.
`
`Antiglobulin response (table ///)-By double-capture
`ELISA, anti-CAMPATH-1H antiglobulins were not
`detected in any patient after one course of therapy, including
`the 2 patients differing in heavy chain allotype from
`CAMPATH-1H. By contrast, 3 of the 4 retreated patients
`(B, D, E) developed antiglobulins 6-10 days after the end of
`retreatment. 2 of these had a pure anti-idiotype response and
`they shared heavy-chain allotype with CAMPATH-1H. It
`was not possible to allotype patient B reliably, and the
`presence of a non-idiotype component in this patient’s
`serum suggests an allotype mismatch. In the functional
`assay, sera from these 3 patients were able to inhibit the
`binding of CAMPATH-1H to human peripheral blood
`lymphocytes as predicted. Unexpectedly, however, sera
`from these and a further 2 patients also showed much weaker
`blocking activity 6-15 days after the first course of therapy.
`This may represent a weak primary antiglobulin response.
`However, it should be noted that in 2 of these patients weak
`activity could be detected even before therapy (and therefore
`may not represent specific antiglobulins but perhaps soluble
`CAMPATH-1H antigen or an effect of rheumatoid
`factors).
`
`Discussion
`To our knowledge this study is the first assessment of
`humanised mAb treatment for rheumatoid arthritis. We
`were unable to detect a significant antiglobulin response
`after one course of therapy but 3 out of 4 retreated patients
`developed antiglobulins and these were able to inhibit the
`binding of CAMPATH-1H to its antigen. We cannot
`conclude from these results whether an allotype mismatch
`
`

`

`752
`
`remission ( > 3 years) than did CAMPATH-1H alone in a
`patient with vasculitis (ref 19 and M. Lockwood, personal
`communication), suggesting that this combination can
`induce tolerance. It is also possible that CAMPATH-1H
`will prove less immunogenic when administered in higher
`doses. Thus, mice do not make an antiglobulin response
`against CD4 mAbs provided a dose above a critical
`minimum is given.2o
`The variation in clinical response that we recorded may
`reflect the complex pathogenesis of rheumatoid arthritis.
`One hypothesis is that monocytes are the cell type that
`ultimately bring about the tissue damage seen in late
`disease,21 but all the data from studies using mAbs and other
`T-cell targeted therapies suggest that, if this hypothesis is
`true, they must be driven by self-reactive T cells.! The rapid
`improvements seen in our patients point to an inflammatory
`role for T cells in late disease. By contrast, the lack of impact
`on ESR and C-reactive protein concentrations suggests that
`in rheumatoid arthritis the acute-phase response is driven by
`monocyte-derived cytokines.22 Use of a two-tiered approach
`that targets both T cells and monocytes may be the ultimte
`requirement.
`immunogenicity
`The reduced
`of
`CAMPATH-1H compared with rodent antibodies and the
`consequent ability to retreat patients with higher doses or
`with other mAbs, will enable us to learn how to use mAbs to
`their best advantage both in rheumatoid arthritis and in
`other autoimmune diseases.
`
`This work was supported by the Medical Research Council (MRC),
`Gilinan Foundation, Kay Kendall Trust, and Wellcome Trust. We thank Dr
`J. Phillips and the staff of the Therapeutic Antibody Centre for antibody
`manufacture; Ms Mary Smith for metrology and thermography; Ms Helen
`Waller, Mr Peppy Rebello, and Ms Sally Coles for expert technical
`assistance; Dr A. Crisp and Dr A. Nichols for referring patients for this study;
`and the staff of Ward F5 at Addenbrooke’s Hospital. J. D. 1. is an MRC
`clinician scientist and a research fellow of Downing College, Cambridge.
`CAMPATH is a trademark owned by Wellcome Foundation, Beckenham,
`Kent.
`
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`
`Maternal relaxin concentrations in diabetic
`pregnancy
`
`Maternal serum concentrations of relaxin, an
`insulin homologue produced both by the corpus
`luteum of pregnancy and by the fetoplacental unit,
`are highest in the first trimester and fall to their lowest
`level in the third trimester. Relaxin is thought to
`influence carbohydrate metabolism in the uterus, and
`it has been suggested that serum concentrations of
`relaxin in diabetic women are higher than those of
`non-diabetic women.
`maternal serum relaxin
`We show that
`concentrations are significantly higher at each stage
`of pregnancy in insulin-dependent diabetic mothers
`than in non-diabetic mothers. This elevation in
`relaxin concentrations is not related to other indices
`of diabetic control. The physiological importance of
`
`the higher concentrations of relaxin in the serum of
`particular, whether they
`diabetic women&mdash;in
`contribute to the higher incidence of major
`anomalies in the fetuses of diabetic mothers&mdash;is yet
`to be determined.
`
`ADDRESSES: Laboratory for Experimental Medicine and
`Surgery in Primates, NYU Medical Center, Tuxedo, New York,
`USA (B. G. Steinetz, PhD); University Department of Obstetrics,
`Princess Mary Maternity Hospital, Newcastle Upon Tyne, UK
`(P G Whitaker, PhD); and Cleft Palate Research Unit, University
`of Newcastle Upon Tyne (J R G Edwards, FRCS). Correspondence
`to Mr J. R G. Edwards, Cleft Palate Research Unit, University of
`Newcastle Upon Tyne, 1-4 Claremont Terrace, Newcastle Upon Tyne,
`NE1 7RU, UK.
`
`