Background: Primary immunodeficiencies represent the ‘molecular Achilles’ heels’ of human immunity. Detailed analyses of primary immunodeficiencies extend our knowledge of pivotal immunological processes, lead to novel diagnostic algorithms and shorten the time to diagnosis. Methods: Clinical/immunological phenotypes of 2 unrelated patients from Austria with combined immunodeficiency were determined. Leukocyte subpopulations of these patients, their parents and healthy controls were analyzed by flow cytometry. Patient-derived Epstein-Barr virus (EBV)-transformed B cell lines were established and complemented by candidate cDNAs. Suspected mutations were confirmed by DNA sequencing. Results: Phenotyping revealed a lack of constitutive human leukocyte antigen (HLA) class II expression on antigen-presenting cells of both patients, compatible with MHC class II deficiency. Rapid vector-based complementation analysis of the patients’ B cells identified HLA class II transactivator (CIITA) deficiency in patient VIP1 and regulatory factor X (RFX)AP deficiency in patient VIP2. CIITA deficiency was caused by a homozygous p.Glu381X mutation. RFXAP deficiency resulted from a homozygous p.Ser123ThrfsX15 mutation, not described in the Middle European population so far. Of note, HLA class II-associated invariant chain (Ii) expression levels were significantly reduced in VIP1 and 3 additional EBV-transformed B cell lines of CIITA-deficient patients but normal in EBV-transformed B cells from VIP2. In addition, peripheral blood B cells from the parents of VIP1 showed significantly reduced HLA-DR and -DP expression levels compared to healthy controls. Conclusions: Analysis of patients’ intracellular Ii and their parents’ surface HLA class II expression levels might help to identify CIITA-deficient patients already during initial phenotyping.

1.
Germain RN: MHC-dependent antigen processing and peptide presentation: providing ligands for T lymphocyte activation. Cell 1994;76:287–299.
2.
Ting JP, Baldwin AS: Regulation of MHC gene expression. Curr Opin Immunol 1993;5:8–16.
3.
Glimcher LH, Kara CJ: Sequences and factors: a guide to MHC class-II transcription. Annu Rev Immunol 1992;10:13–49.
4.
Mach B, Steimle V, Martinez-Soria E, Reith W: Regulation of MHC class II genes: lessons from a disease. Annu Rev Immunol 1996;14:301–331.
5.
Reith W, Mach B: The bare lymphocyte syndrome and the regulation of MHC expression. Annu Rev Immunol 2001;19:331–373.
6.
Nekrep N, Fontes JD, Geyer M, Peterlin BM: When the lymphocyte loses its clothes. Immunity 2003;18:453–457.
7.
Waldburger JM, Masternak K, Muhlethaler-Mottet A, Villard J, Peretti M, Landmann S, Reith W: Lessons from the bare lymphocyte syndrome: molecular mechanisms regulating MHC class II expression. Immunol Rev 2000;178:148–165.
8.
Reith W, Lisowska-Grospierre B, Fischer A: Molecular Basis of Major Histocompatibility Complex Class II Deficiency, ed 2. New York, Oxford University Press, 2007.
9.
Klein C, Lisowska-Grospierre B, LeDeist F, Fischer A, Griscelli C: Major histocompatibility complex class II deficiency: clinical manifestations, immunologic features, and outcome. J Pediatr 1993;123:921–928.
10.
Steimle V, Otten LA, Zufferey M, Mach B: Complementation cloning of an MHC class II transactivator mutated in hereditary MHC class II deficiency (or bare lymphocyte syndrome). Cell 1993;75:135–146.
11.
Masternak K, Barras E, Zufferey M, Conrad B, Corthals G, Aebersold R, Sanchez JC, Hochstrasser DF, Mach B, Reith W: A gene encoding a novel RFX-associated transactivator is mutated in the majority of MHC class II deficiency patients. Nat Genet 1998;20:273–277.
12.
Nagarajan UM, Louis-Plence P, DeSandro A, Nilsen R, Bushey A, Boss JM: RFX-B is the gene responsible for the most common cause of the bare lymphocyte syndrome, an MHC class II immunodeficiency. Immunity 1999;10:153–162.
13.
Steimle V, Durand B, Barras E, Zufferey M, Hadam MR, Mach B, Reith W: A novel DNA-binding regulatory factor is mutated in primary MHC class II deficiency (bare lymphocyte syndrome). Genes Dev 1995;9:1021–1032.
14.
Durand B, Sperisen P, Emery P, Barras E, Zufferey M, Mach B, Reith W: RFXAP, a novel subunit of the RFX DNA binding complex is mutated in MHC class II deficiency. EMBO J 1997;16:1045–1055.
15.
Steinberger P, Majdic O, Derdak SV, Pfistershammer K, Kirchberger S, Klauser C, Zlabinger G, Pickl WF, Stockl J, Knapp W: Molecular characterization of human 4Ig-B7-H3, a member of the B7 family with four Ig-like domains. J Immunol 2004;172:2352–2359.
16.
Derdak SV, Kueng HJ, Leb VM, Neunkirchner A, Schmetterer KG, Bielek E, Majdic O, Knapp W, Seed B, Pickl WF: Direct stimulation of T lymphocytes by immunosomes: virus-like particles decorated with T cell receptor/CD3 ligands plus costimulatory molecules. Proc Natl Acad Sci USA 2006;103:13144–13149.
17.
Pear WS, Nolan GP, Scott ML, Baltimore D: Production of high-titer helper-free retroviruses by transient transfection. Proc Natl Acad Sci USA 1993;90:8392–8396.
18.
Quan V, Towey M, Sacks S, Kelly AP: Absence of MHC class II gene expression in a patient with a single amino acid substitution in the class II transactivator protein CIITA. Immunogenetics 1999;49:957–963.
19.
Bontron S, Steimle V, Ucla C, Eibl MM, Mach B: Two novel mutations in the MHC class II transactivator CIITA in a second patient from MHC class II deficiency complementation group A. Hum Genet 1997;99:541–546.
20.
Mannhalter JW, Wolf HM, Gadner H, Potschka M, Eibl MM: Cell-mediated immune functions in a patient with MHC class II deficiency. Immunol Invest 1991;20:151–167.
21.
Fondaneche MC, Villard J, Wiszniewski W, Jouanguy E, Etzioni A, Le Deist F, Peijnenburg A, Casanova JL, Reith W, Mach B, Fischer A, Lisowska-Grospierre B: Genetic and molecular definition of complementation group D in MHC class II deficiency. Hum Mol Genet 1998;7:879–885.
22.
Villard J, Lisowska-Grospierre B, van den Elsen P, Fischer A, Reith W, Mach B: Mutation of RFXAP, a regulator of MHC class II genes, in primary MHC class II deficiency. N Engl J Med 1997;337:748–753.
23.
Rocha N, Neefjes J: MHC class II molecules on the move for successful antigen presentation. EMBO J 2008;27:1–5.
24.
Tai AK, Zhou G, Chau K, Ono SJ: Cis-element dependence and occupancy of the human invariant chain promoter in CIITA-dependent and -independent transcription. Mol Immunol 1999;36:447–460.
25.
Matheux F, Ikinciogullari A, Zapata DA, Barras E, Zufferey M, Dogu F, Regueiro JR, Reith W, Villard J: Direct genetic correction as a new method for diagnosis and molecular characterization of MHC class II deficiency. Mol Ther 2002;6:824–829.
26.
Piirila H, Valiaho J, Vihinen M: Immunodeficiency mutation databases (IDbases). Hum Mutat 2006;27:1200–1208.
27.
Zhou H, Glimcher LH: Human MHC class II gene transcription directed by the carboxyl terminus of CIITA, one of the defective genes in type II MHC combined immune deficiency. Immunity 1995;2:545–553.
28.
Chang CH, Fontes JD, Peterlin M, Flavell RA: Class II transactivator (CIITA) is sufficient for the inducible expression of major histocompatibility complex class II genes. J Exp Med 1994;180:1367–1374.
29.
Peijnenburg A, Van Eggermond MJ, Gobin SJ, Van den Berg R, Godthelp BC, Vossen JM, Van den Elsen PJ: Discoordinate expression of invariant chain and MHC class II genes in class II transactivator-transfected fibroblasts defective for RFX5. J Immunol 1999;163:794–801.
30.
Leng L, Metz CN, Fang Y, Xu J, Donnelly S, Baugh J, Delohery T, Chen Y, Mitchell RA, Bucala R: MIF signal transduction initiated by binding to CD74. J Exp Med 2003;197:1467–1476.
31.
Shi X, Leng L, Wang T, Wang W, Du X, Li J, McDonald C, Chen Z, Murphy JW, Lolis E, Noble P, Knudson W, Bucala R: CD44 is the signaling component of the macrophage migration inhibitory factor-CD74 receptor complex. Immunity 2006;25:595–606.
32.
Chang CH, Flavell RA: Class II transactivator regulates the expression of multiple genes involved in antigen presentation. J Exp Med 1995;181:765–767.
33.
Masternak K, Reith W: Promoter-specific functions of CIITA and the MHC class II enhanceosome in transcriptional activation. EMBO J 2002;21:1379–1388.
34.
Nagarajan UM, Peijnenburg A, Gobin SJ, Boss JM, van den elsen PJ: Novel mutations within the RFX-B gene and partial rescue of MHC and related genes through exogenous class II transactivator in RFX-B-deficient cells. J Immunol 2000;164:3666–3674.
35.
Peijnenburg A, Van Eggermond MC, Van den Berg R, Sanal O, Vossen JM, Van den Elsen PJ: Molecular analysis of an MHC class II deficiency patient reveals a novel mutation in the RFX5 gene. Immunogenetics 1999;49:338–345.
36.
Hoffman R, Benz EJ, Shattil S, Furie B, Cohen HJ, Silberstein LE, McGlave P: Hematology: Basic Principles and Practice, ed 3. Philadelphia, Churchill Livingstone, 2000.
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.