Immunological and genetic analysis of 65 patients with a clinical suspicion of X linked hyper-IgM

BACKGROUND

X linked hyper-IgM (XHIM) is a primary immunodeficiency caused by mutations in the tumour necrosis factor superfamily 5 gene, TNFSF5, also known as the CD40 ligand (CD40L) gene. Patients often present with recurrent infections, and confirmation of a diagnosis of XHIM enables appropriate therapeutic interventions, including replacement immunoglobulin, antibiotics, and bone marrow transplantation.

AIM

To review and optimise the institution's diagnostic strategy for XHIM.

METHOD

Samples from 65 boys were referred to this centre for further investigation of suspected XHIM. The results, which included a flow cytometric whole blood assay for CD40L expression followed by mutation analysis in selected patients, were reviewed.

RESULTS

Twenty one patients failed to express CD40L and TNFSF5 mutations were found in 20 of these patients. In contrast, no TNFSF5 mutations were found in 16 patients with weak expression of CD40L. Interestingly, one quarter of patients with confirmed XHIM who had TNFSF5 mutations had low concentrations of IgG, IgA, and IgM. Most of the remaining patients with XHIM had the classic pattern of normal or raised IgM with low concentrations of IgA and IgG.

CONCLUSIONS

This study demonstrates the usefulness of the whole blood staining method as a rapid screen to select patients for subsequent TNFSF5 mutation analysis, and shows the benefits of a unified protein/genetic diagnostic strategy.

Absence of platelet CD40L identifies patients with X-linked hyper IgM syndrome

CD40 ligand (CD40L), a membrane protein expressed on activated T cells, plays a pivotal role in B cell proliferation and differentiation. Mutations in the CD40L gene are associated with a rare immunodeficiency state, X-linked hyper IgM syndrome (XLHIGM). Recently, platelets have been described as capable of expressing CD40L within minutes of stimulation. We have developed a rapid technique to determine expression of CD40L on activated platelets by flow cytometry in whole blood. We have demonstrated that this technique is useful in neonatal screening, in rapid diagnosis and in determining reconstitution by donor bone marrow post-transplantation.

Intra-amniotic inflammation in human gastroschisis: possible aetiology of postnatal bowel dysfunction

OBJECTIVE

To assess amniotic fluid for evidence of an inflammatory exudate in association with fetal gastroschisis.

SETTING

University College Hospital, London and Institute of Child Health, London.

SAMPLE

Samples of amniotic fluid in the third trimester from pregnant women with a diagnosis of fetal gastroschisis (n = 10) and from a control group (n = 10) with a normal fetus.

METHODS

Cytological analysis of the fluid was performed. Flow cytometry was performed on the amniotic fluid using antibodies for the myeloid cell antigen CD15, the leucocyte beta integrin CD11b/CD18 and CD3, CD19, CD56 and CD25. Tumour necrosis factor alpha and interleukin-8 levels were assayed in the amniotic fluid.

RESULTS

An acute inflammatory exudate, composed predominantly of neutrophil polymorphs and mononuclear cells, was found in the amniotic fluid in fetal gastroschisis but not in control cases. When amniotic fluid samples from cases of fetal gastroschisis were stained with CD15, analysis by flow cytometry showed a clear positive population. This CD15 population showed markedly elevated levels of CD11b. No distinct population of CD15 positive cells was seen in amniotic fluid samples examined from the control group. No staining was seen with antibodies to CD3, CD19, CD56 or CD25 in amniotic fluid obtained from either group. There was no significant difference between tumour necrosis factor alpha levels measured in the amniotic fluid of cases of fetal gastroschisis (median 102 pg/mL; range 20-340) and those of the control group (140 pg/mL; range 20-548) (P = 0.1). The levels of interleukin-8 were markedly elevated in the amniotic fluid of cases of fetal gastroschisis (median 6320 pg/mL; range 4732-13,800) compared with the control group (median 1738 pg/mL; range 623 2861;) (P < 0.01).

CONCLUSION

Human fetal gastroschisis is associated with an inflammatory exudate in the amniotic fluid which may have implications for postnatal bowel function.

Albumin synthesis rates in cirrhosis: correlation with Child-Turcotte classification

Albumin-synthesis rates were measured in nine patients with stable cirrhosis and compared with those of eight healthy volunteers by means of a new technique using stable isotopes. Four grams of L-[1-13C]leucine was injected over 10 min, and blood samples were drawn at intervals. Serum free [13C]leucine enrichment, taken to be the precursor for albumin synthesis, and 13C enrichment of leucine in albumin, isolated with differential solubility in absolute ethanol from trichloracetic acid-precipitated serum proteins, were measured on mass spectrometry. Albumin synthesis, expressed as a fractional rate, was 7.9% +/- 0.3%/day in the controls and 7.9% +/- 1.1%/day in the cirrhotic patients. Albumin synthesis, expressed as an absolute rate, was lower in the cirrhotic group (cirrhotic, 119 +/- 17 mg/kg/day; controls, 146 +/- 8 mg/kg/day), but because of the relatively small number of patients the difference was not significant. However, the absolute rate of albumin synthesis significantly correlated with the Child-Turcotte score (p = 0.024) and its Pugh modification (p = 0.027). The rate of albumin synthesis also correlated with serum phenylalanine concentration but not with serum albumin concentration and intravascular albumin mass or with other clinical indexes of liver function or integrity when taken separately. However, the significant correlation between albumin synthesis and Child score suggests that albumin synthesis might be useful for the clinical judgment of patients with cirrhosis.

Season of birth in schizophrenia. Evidence for confinement of an excess of winter births to patients without a family history of mental disorder

Although it is well recognised that schizophrenic patients are more often born in winter, the significance of this finding remains obscure. Data relating to season of birth and family history were analysed for 561 patients with an ICD-9 diagnosis of schizophrenia. Patients with no family history of any psychiatric disorder group were significantly more likely to be born in winter than patients with a first-degree relative affected by schizophrenia. In comparison with normal population controls, only those without a family history exhibited a significant excess of winter births, suggesting an environmental factor of greater aetiological significance in these patients.