Functional characterization of natural killer cells in type I leukocyte adhesion deficiency.

In this study, we analyzed IL-2-activated polyclonal natural killer (NK) cells derived from 2 patients affected by leukocyte adhesion deficiency type I (LAD1), an immunodeficiency characterized by mutations of the gene coding for CD18, the beta subunit shared by major leukocyte integrins. We show that LAD1 NK cells express normal levels of various triggering NK receptors (and coreceptors) and that mAb-mediated engagement of these receptors results in the enhancement of both NK cytolytic activity and cytokine production. Moreover, these activating NK receptors were capable of recognizing their specific ligands on target cells. Thus, LAD1 NK cells, similarly to normal NK cells, were capable of killing most human tumor cells analyzed and produced high amounts of IFN-gamma when cocultured in presence of target cells. Murine target cells represented a common exception, as they were poorly susceptible to LAD1 NK cells. Finally, LAD1 NK cells could efficiently kill or induce maturation of monocyte-derived immature dendritic cells (DCs). Altogether our present study indicates that in LAD1 patients, 3 important functions of NK cells (eg, cytotoxicity, IFN-gamma production, and DC editing) are only marginally affected and provides new insight on the cooperation between activating receptors and LFA-1 in the induction of NK cell activation and function.

Clinical, immunological and molecular characteristics of 37 Iranian patients with X-linked agammaglobulinemia.

BACKGROUND: X-linked agammaglobulinemia (XLA) is a hereditary immunodeficiency characterized by an early onset of recurrent bacterial infections, a profound deficiency of all immunoglobulin isotypes and a markedly reduced number of peripheral B lymphocytes. Eighty-five percent of the patients with this phenotype have mutations in Bruton's tyrosine kinase (BTK) gene. METHODS: To provide an informative outlook of clinical and immunological manifestations of XLA in Iran, 37 Iranian male patients with an age range of 1-34 years, followed over a period of 25 years, were studied. Twenty-four of the 37 patients were screened for BTK gene mutation using PCR-SSCP followed by direct sequencing. BTK protein expression assay was done by flow cytometry in 9 families. RESULTS: All patients first presented with infectious diseases, the most common of which were respiratory tract infections. Eighteen different mutations were identified, 13 of which were novel: IVS1+5G>C, 1896G>A, 349delA, 1618C>T, 1783T>C, 2084A>G, 1346delT, 1351delGAG, 587A>G, IVS14-1G>A, IVS3+2T>C, 1482G>A, 1975C>A. CONCLUSION: The fact that we found a great number of novel mutations in a relatively limited number of patients underlines the heterogeneity of BTK mutations in the Iranian population. The large number of new mutations indicates that extended studies in this region would be rewarding.

T-cell lymphoblastic leukemia/lymphoma in Nijmegen breakage syndrome.

Nijmegen breakage syndrome (NBS) is a rare autosomal-recessive disorder characterized by microcephaly, immunodeficiency and predisposition to cancer, mainly B-cell lymphomas. Our 10-years-old female patient with NBS developed T-cell lymphoblastic leukemia/lymphoma (TLBL/ALL). The use of standard chemotherapy in our patient, except for cranial irradiation, led to complete and sustained remission of TLBL/ALL. In patients with chromosomal instability syndromes chemotherapy must be modified and radiotherapy must be omitted because of potentially serious toxic complications. Careful prevention of infections, including the use of intravenous immunoglobulin is also essential for successful treatment of lymphoid malignancies in NBS. Immunodeficiency in NBS is profound affecting both humoral and cellular immune system. During long-term follow-up after treatment of malignancy our patient remained free of major infections However, the rise of oligoclonal serum IgM was detected recently. Monitoring of serum IgM concentration may be a useful indicator for early detection of lymphomas in NBS.

Mutations of the Wiskott-Aldrich Syndrome Protein (WASP): hotspots, effect on transcription, and translation and phenotype/genotype correlation.

The Wiskott-Aldrich syndrome (WAS) is an X-linked recessive immune deficiency disorder characterized by thrombocytopenia, small platelet size, eczema, recurrent infections, and increased risk of autoimmune disorders and malignancies. X-linked thrombocytopenia (XLT) is an allelic variant of WAS which presents with a milder phenotype, generally limited to thrombocytopenia. WAS and XLT are caused by mutations of the Wiskott-Aldrich syndrome protein (WASP) gene which encodes a 502-amino acid protein, named WASP. WASP is thought to play a role in actin cytoskeleton organization and cell signaling. Here, we report the identification of 141 unique mutations, 71 not previously reported, from 227 WAS/XLT families with a total of 262 affected members. When possible we studied the effects of these mutations on transcription, RNA splicing, and protein expression. By analyzing a large number of patients with WAS/XLT at the molecular level we identified 5 mutational hotspots in the WASP gene and have been able to establish a strong association between genotype and phenotype.

BTK: 22 novel and 25 recurrent mutations in European patients with X-linked agammaglobulinemia.

X linked agammaglobulinemia (XLA) is an immunodeficiency disease caused by mutations in the gene coding for Bruton's agammaglobulinemia tyrosine kinase (BTK), that is involved in signal transduction pathways regulating survival, activation, proliferation, and differentiation of B lineage lymphoid cells. XLA is a primary immunodeficiency disorder characterized by lack of mature, circulating B lymphocytes, and recurrent infections. Using Single Strand Conformation Polymorphism (SSCP) followed by direct sequencing we investigated 57 patients with XLA phenotype, with or without a positive family history, from 52 unrelated families enrolled in the Italian XLA Multicenter Clinical Study. We have identified 25 recurrent mutations, 22 novel mutations including one large deletion comprising the coding sequence from exon 11 to 18. Among the mutations identified, three were detected in different unrelated families, whereas all the others were private mutations.

Defective migration of monocyte-derived dendritic cells in LAD-1 immunodeficiency.

beta2 Integrins (CD18) are required for leukocyte migration. In fact, the absence of CD18 results in type-1 leukocyte adhesion deficiency (LAD-1). We analyzed the distribution phenotype and function of dendritic cells (DCs) in three LAD-1 patients with homozygous mutations of CD18. Two of them did not express CD18 (Patients A and C), and the other subject (Patient B) displayed reduced expression of beta2 integrins because of a missense mutation. Analysis of DCs derived from Patients A and B showed an abnormal morphology and a severe impairment in transendothelial migration and chemotactic response to CCL19/macrophage inflammatory protein-3beta, suggesting that CD18 is required for migration of monocyte-derived DCs. Nevertheless, DCs displayed normal macropinocytosis and underwent normal maturation after addition of tumor necrosis factor alpha. Finally, immunohistochemical analysis of lymph nodes from subjects B and C revealed a significant reduction in the number of factor-XIIIa(+) interstitial DCs in the interfollicular area in both patients, suggesting that CD18 plays a role in the migration of these cells in vivo.

Clinical, immunological, and molecular analysis in a large cohort of patients with X-linked agammaglobulinemia: an Italian multicenter study.

A questionnaire-based retrospective clinical and immunological survey was conducted in 73 males with a definite diagnosis of X-linked agammaglobulinemia based on BTK sequence analysis. Forty-four were sporadic and 29 familial cases. At December 2000, the patients' ages ranged from 2 to 33 years; mean age at diagnosis and mean duration of follow-up were 3.5 and 10 years respectively. After the mid-1980s all but 2 were on intravenous immunoglobulin (IVIG) substitution therapy, with residual IgG >500 mg/dl in 94% of the patients at the time of enrollment. Respiratory infections were the most frequent manifestation both prior to diagnosis and over follow-up. Chronic lung disease (CLD) was present in 24 patients, in 15 already at diagnosis and in 9 more by 2000. The cumulative risk to present at diagnosis with CLD increased from 0.17 to 0.40 and 0.78 when the diagnosis was made at the ages of 5, 10, and 15 years respectively. For the 9 patients who developed CLD during follow-up, the duration of follow-up, rather than age at diagnosis; previous administration of intramuscular immunoglobulin; and residual IgG levels had a significant effect on the development of CLD. Chronic sinusitis was present in 35 patients (48%), in 15 already at diagnosis and in 20 by 2000. Sistemic infections such as sepsis and meningitis/meningoencephalitis decreased over follow-up, probably due to optimal protection provided by high circulating IgG levels reached with IVIG.