Dysgammaglobulinemia Associated With Glu349del, a Hypomorphic XIAP Mutation

BACKGROUND

X-linked lymphoproliferative syndrome type 2 is a rare hereditary immunodeficiency caused by mutations in the XIAP gene. This immunodeficiency frequently results in hemophagocytic lymphohistiocytosis, although hypogammaglobulinemia and dysgammaglobulinemia are also common.

OBJECTIVE

We identified 17 patients from 12 Japanese families with mutations in XIAP. The Glu349del mutation was observed in 3 patients, each from a different family. Interestingly, these patients exhibited dysgammaglobulinemia but not hemophagocytic lymphohistiocytosis. We conducted an immunological study of patients carrying Glu349del and other mutations to elucidate the pathogenic mechanisms of dysgammaglobulinemia in patients with mutations in the XIAP gene.

PATIENTS AND METHODS

We performed an immunological study of 2 patients carrying the Glu349del mutation and 8 patients with other mutations.

RESULTS

Flow cytometry showed that the percentage of memory B cells in patients with a mutation in XIAP was lower than that observed in the healthy controls. The patients with the Glu349del mutation had a lower percentage of memory B cells than those with other mutations. Ig production was reduced in patients with the Glu349del mutation. Increased susceptibility to apoptosis was observed in the patients with other mutations. Susceptibility to apoptosis was normal in patients with Glu349del. Microarray analysis indicated that expression of Ig-related genes was reduced in patients with the Glu349del mutation and that the pattern was different from that observed in the healthy controls or patients with other mutations in XIAP.

CONCLUSIONS

Patients carrying the Glu349del mutation in the XIAP gene may have a clinically and immunologically distinct phenotype from patients with other XIAP mutations. The Glu349del mutation may be associated with dysgammaglobulinemia.

Selective IgM deficiency and 22q11.2 deletion syndrome

BACKGROUND

The 22q11.2 deletion syndrome is a common chromosomal disorder with highly variable phenotypic expression and immunologic defects. Humoral immunity is mostly unaffected, but selective IgA deficiency occurs in up to 13% of patients. Selective IgM deficiency associated with 22q11.2 deletion has been reported in 1 patient.

OBJECTIVE

To describe another 2 patients with 22q11.2 deletion syndrome and IgM deficiency.

METHODS

Patient 1 was a 6-year-old boy with recurrent otitis media, sinopulmonary infections, wheezing, and speech delay. His serum IgM level was 18 mg/dL, and his IgA and IgG levels were normal. Antibody titers to protein and carbohydrate antigens were protective. Workup for velopharyngeal insufficiency resulted in the diagnosis of 22q11.2 deletion syndrome 3 years later. Patient 2 was a 14-year-old girl diagnosed as having 22q11.2 deletion at 9 years of age after presenting with neonatal seizures, atrial and ventricular septal defects, recurrent otitis media, mental retardation, and asthma. Her serum IgM level was 11 mg/dL, with normal IgG and IgA levels. Antibody titers to protein and carbohydrate antigens were protective. Patient 3 was a previously described 15-year-old girl with persistently draining ears, 22q11.2 deletion, and an IgM level less than 6 mg/dL. Her clinical and laboratory features are summarized.

RESULTS

Results of further testing on the patients, including lymphocyte enumeration, were normal. The literature is reviewed regarding decreased IgM levels in 22q11.2 deletion syndrome.

CONCLUSIONS

Fluorescence in situ hybridization analysis for chromosome 22q11.2 deletion should be considered in patients with selective IgM deficiency, especially if concurrent chronic otitis media, developmental delay, velopharyngeal insufficiency, or dysmorphic features are present.

Linkage of autosomal-dominant common variable immunodeficiency to chromosome 4q

The phenotype of common variable immunodeficiency (CVID) is characterized by recurrent infections owing to hypogammaglobulinemia, with deficiency in immunoglobulin (Ig)G and at least one of IgA or IgM. Family studies have shown a genetic association between CVID and selective IgA deficiency (IgAD), the latter being a milder disorder compatible with normal health. Approximately 20-25% of CVID cases are familial, if one includes families with at least one case of CVID and one of IgAD. Nijenhuis et al described a five-generation family with six cases of CVID, five cases of IgAD, and three cases of dysgammaglobulinemia. We conducted a genome-wide scan on this family seeking genetic linkage. One interval on chromosome 4q gives a peak multipoint LOD score of 2.70 using a strict model that treats only the CVID patients and one obligate carrier with dysgammaglobulinemia as affected. Extending the definition of likely affected to include IgAD boosts the peak multipoint LOD score to 3.38. The linkage interval spans at least from D4S2361 to D4S1572. We extended our study to a collection of 32 families with at least one CVID case and a second case of either CVID or IgAD. We used the same dominant penetrance model and genotyped and analyzed nine markers on 4q. The 32 families have a peak multipoint LOD score under heterogeneity of 0.96 between markers D4S423 and D4S1572 within the suggested linkage interval of the first family, and an estimated proportion of linked families (alpha) of 0.32, supporting the existence of a disease-causing gene for autosomal-dominant CVID/IgAD on chromosome 4q.

Primary immunodeficiency in combination with transverse upper limb defect and anal atresia in a 34-year-old patient with Jacobsen syndrome

We describe a 34-year-old male patient with Jacobsen syndrome associated with a broad spectrum of anomalies and an increased susceptibility to infections. Features commonly seen in Jacobsen syndrome were short stature, mental retardation, congenital heart disease, cryptorchidism, strabismus, distal hypospadia glandis, and mild thrombocytopenia. Chromosome analysis disclosed a mosaic 46,XY,del(11)(q24.1)/46,XY karyotype with a very low percentage of normal cells. In addition, transverse upper limb defect, imperforate anus, and hearing impairment were noted. Cellular anomalies include functional impairment and deficiency of T-helper cells, and a low serum immunoglobulin M (IgM)-level. The presence of a transverse limb defect and primary immunodeficiency has not been reported previously in Jacobsen syndrome.

Long term maintenance of IgE-mediated memory in mast cells in the absence of detectable serum IgE

Mast cells and basophils involved in allergic responses do not have clonotypic Ag receptors. However, they can acquire Ag specificity through binding of Ag-specific IgE to FcepsilonRI expressed on their surface. Previous studies demonstrated that IgE binding induced the stabilization and accumulation of FcepsilonRI on the cell surface and resulted in up-regulation of FcepsilonRI. In this study we have further analyzed the maintenance of IgE-mediated memory in mast cells and basophils in vivo by comparing kinetics of serum IgE levels, FcepsilonRI expression, and ability to induce systemic anaphylaxis. A single i.v. injection of trinitrophenyl-specific IgE induced 8-fold up-regulation of FcepsilonRI expression on peritoneal mast cells in B cell-deficient (micro m(-/-)) mice. Serum IgE levels became undetectable by day 6, but the treatment of mice with anti-IgE mAb induced a significant drop in body temperature on days 14, 28, and 42. The administration of trinitrophenyl -BSA, but not BSA, in place of anti-IgE mAb gave similar results, indicating the Ag specificity of the allergic response. This long term maintenance of Ag-specific reactivity in the allergic response was also observed in normal mice passively sensitized with IgE even though the duration was shorter than that in B cell-deficient mice. The appearance of IgE with a different specificity did not interfere with the maintenance of IgE-mediated memory of mast cells and basophils. These results suggest that IgE-mediated stabilization and up-regulation of FcepsilonRI enables mast cells and basophils not only to acquire Ag specificity, but also to maintain memory in vivo for lengthy periods of time.

Common variable immunodeficiency (CVID) in a family: an autosomal dominant mode of inheritance

BACKGROUND

Common variable immunodeficiency (CVID) is characterised by a late onset deficiency of immunoglobulins resulting in recurrent infectious and non-infectious ailments. Most cases are sporadic but occasional familial clustering has been described. We present an extensively affected family with CVID in three consecutive generations.

METHODS

We conducted a study in this family to establish clinical phenotype, to clarify the mode of inheritance and to attempt to characterise the immune disturbance by determining immunoglobulin concentrations and B- and T-cell analysis.

RESULTS

We describe six patients with CVID in three consecutive generations. In addition, we encountered 10 family members with dysimmunoglobulinemia. B-cell counts were normal, but T-cell analysis showed slightly abnormal results.

CONCLUSIONS

The six cases of overt late onset hypogammaglobulinemia are compatible with an autosomal dominant mode of inheritance. The family members with dysimmunoglobulinemia may be at risk to develop overt CVID in the future, in view of the gradual course of progression of the disease in the clinically affected family members. B- and T-cell analysis are inconclusive though may support a possible defect in T-cell function to be involved. To further study this remarkable family and attempt to clarify pathogenesis, we are planning DNA linkage analysis in the near future.

Immunologic reconstitution following bone marrow transplantation for X-linked hyper IgM syndrome

X-linked hyper IgM syndrome (XHIM), caused by mutations of the CD40 ligand (CD40L) gene, is characterized by recurrent bacterial and opportunistic infections, an increased incidence of autoimmunity and malignancies, and immunodeficiency due to abnormal T/B cell interaction. Because of poor long-term prognosis, bone marrow transplantation (BMT) has been proposed as an alternative treatment. An 8-month-old boy with XHIM and a splice site mutation of CD40L underwent BMT using a fully matched sibling donor. Markers of engraftment and immunologic reconstitution were measured serially. After BMT, activated T cells expressed functional CD40L, and genomic DNA obtained from circulating white cells contained predominantly wild-type CD40L sequences. Serum immunoglobulin levels including IgE and antibody responses to recall antigens normalized, and immunization with the T-cell-dependent neoantigen, bacteriophage φX174, demonstrated amplification of the response and isotope switching. BMT provides a permanent cure for XHIM if a fully matched sibling donor is available and the procedure is performed before complications have occurred.

X-linked hyper IgM syndrome: a report of the first case in Thailand with a confirmed mutation of CD40 ligand gene

X-linked hyper IgM (XHIM) syndrome is a rare congenital immunodeficiency disease caused by failure of B cell to isotype switch from IgM to other classes of immunoglobulins in response to infections. Recently, a molecular cloning of the gene responsible for the syndrome, the CD40L gene has been accomplished and the gene was successfully mapped to the long arm of X chromosome at the position Xq26. We, herein, report the first case of molecular proven XHIM in a Thai boy with a classic presentation and with a confirmed mutation of the CD40L gene.

CASE REPORT

A.S. was a 1 year 7 month old boy referred from Buriram Provincial Hospital for a work up and treatment for his recurrent infections consisted of chronic respiratory tract infections with otitis media (since 6 months of age), chronic diarrhea (since 9 months of age) and malnutrition (marasmus) secondary to his longstanding illnesses. He was a product of a consanguineous marriage but without history of similar illness observed in his pedigree. Abnormal laboratory works up included IgG of 300 mg/dl, IgA 10 mg/dl, IgM 1,635 mg/dl, positive stool examinations for Cryptosporidium, chronic colitis on radiographic gastrointestinal follow through study, a positive acid fast bacillus (AFB) stain of gastric aspirate and multiple positive bacterial cultures from various body sources. His anti-HIV serology was negative. His hospital course was significant for several bouts of infections of gastrointestinal, respiratory, and genitourinary systems. His treatment consisted of multiple courses of antibiotics, antituberculous drugs and IVIG administrations. His hospital course was complicated with feeding problem from an esophageal stricture requiring several esophageal dilatations. The analysis of CD40L gene revealed a point mutation of exon 5 (A619T) of the CD40L gene resulting in a stop codon confirming that indeed he had XHIM. He died with Pseudomonas septicemia during the waiting period for a bone marrow transplantation from a cord-blood stem cell.

The [HLA-B18, F1C30, DR3] conserved extended haplotype carries a susceptibility gene for IgD deficiency

We showed previously that the conserved extended MHC haplotype [HLA-B8, SCO1, DR3] carries recessive susceptibility genes for IgA and IgG4 deficiency and dominant genes for IgD and IgG3 deficiency. [HLA-B18, F1C30, DR3] has similar class II and III regions to [HLA-B8, SC01, DR3] and is common in the Basques. We therefore studied serum immunoglobulin concentrations in Basque homozygotes, heterozygotes, and noncarriers of (FIC30, DRB1*0301, DRB3*02, DQA1*0501. DQB1*0201) (F1C30, DR3). As shown by others, no subjects were deficient in IgA, IgM, or IgG subclasses. In contrast, 29% of homozygotes and three of seven double heterozygotes with (SC01, DRB1*0301, DRB3*0101, DQA1*0501, DQB1*0201) (presumed homozygotes for IgD deficiency susceptibility genes) were IgD deficient. Thus, 32% of presumed homozygotes were IgD deficient compared with 1.6% of noncarriers. Of haplotype heterozygotes, 25% were IgD deficient. The high frequency of IgD deficiency in both homozygotes and heterozygotes for (F1C30, DR3) suggests a partially penetrant dominant susceptibility gene for IgD deficiency on [HLA-B18, F1C30, DR3].

Immunogenetics: changing the face of immunodeficiency

Tables 1 and 2 highlight the enormous advances that have been made in the definition of the molecular defects underlying primary immunodeficiencies in the past decade. The identification of SAP as the gene defective in XLP now completes the molecular bases of all the recognised X linked syndromes. Of the autosomally inherited syndromes, only the genes for DiGeorge syndrome, hyper-IgE, and perhaps most importantly, common variable immunodeficiency remain to be elucidated. The major clinical benefits of this information have primarily been in offering more accurate and rapid molecular diagnoses. The ability to make a molecular diagnosis also increases the options for earlier definitive treatments such as bone marrow transplantation and somatic gene therapy. Finally, as illustrated by the studies on the functions of WASP and the gamma c/JAK-3 pathway, identification of the gene defect is the first step to understanding the molecular pathogenesis of the immunological abnormalities.

Complete primary sequences of two lambda immunoglobulin light chains in myelomas with nonamyloid (Randall-type) light chain deposition disease

We herein report on the first two primary sequences (BOU and RAC) of monoclonal light chains of the lambda type responsible for nonamyloid lambda light chain deposition disease. Both patients were affected with severe forms of myeloma complicated with renal failure. The pathological presentation typically featured Congo red-negative deposits along tubular basement membranes but differed somewhat from the typical "Randall-type" kappa light chain deposition disease: they lacked the prominent glomerulosclerosis pattern often featuring nonamyloid kappa deposits and were associated with cylinders or myeloma casts. Both protein sequences were deduced from those of the corresponding complementary DNAs in the bone marrow plasma cells. For each chain, products of three independent amplifications by polymerase chain reaction were sequenced and found to be identical. BOU and RAC lambda mRNAs had a normal overall structure consisting of Vlambda2 segments rearranged to Jlambda2Clambda2 but displayed a number of unusual features within their primary sequences. These substitutions are likely responsible for changes in light chain conformation that promote their aggregation and deposition along renal tubule basement membranes.

Mucocutaneous manifestations of the hyper-IgM immunodeficiency syndrome

BACKGROUND

The recurrent pyogenic infections of patients with hyper-IgM syndrome are controlled by intravenous gamma globulin administration, but patients may suffer from early-onset oral ulcerations and warts.

OBJECTIVE

We have characterized the mucocutaneous manifestations associated with this condition to allow physicians to more readily identify it.

METHODS

Three male patients with the mucocutaneous manifestations of the hyper-IgM syndrome are described. In one, histopathologic examination of the oral mucosal lesion was performed.

RESULTS

Recurrent large, painful oral ulcerations can occur that are not necessarily associated with neutropenia nor do they respond to granulocyte colony-stimulating factor administration. Histopathologic examination of an ulcer showed a heavy infiltrate of mixed inflammatory cells. Warts tend to be widespread and resistant to traditional therapy.

CONCLUSION

Physicians should consider this uncommon condition when examining a male patient with severe oral ulcers or recalcitrant widespread warts.

Antibody independent crescentic glomerulonephritis in mu chain deficient mice

The hypothesis that crescent formation in glomerulonephritis (GN) is a delayed type hypersensitivity (DTH)-like lesion, not dependent on a humoral immune response, was addressed using mice with deletion of the mu immunoglobulin heavy chain gene (mu chain deficient mice). Homozygous mu chain deficient mice do not develop mature B cells or produce immunoglobulin, but have intact cell mediated immunity. GN was induced in sensitized mice by a subnephritogenic dose of sheep anti-mouse GBM globulin. Heterozygous mice (mu chain +/-) demonstrated normal antibody and DTH responses to sheep globulin and developed a proliferative GN with proteinuria (6.4 +/- 1.4 mg/24 hr), renal impairment (serum creatinine 32.6 +/- 3.3 mumol/liter) and crescents in 33 +/- 24% of glomeruli, when this antigen was planted in their glomeruli. This lesion was demonstrated to be T cell dependent by in vivo T cell depletion. Homozygous mu chain deficient mice (-/-) also developed proliferative GN, histologically indistinguishable from +/- mice. Proteinuria (3.8 +/- 1.0 mg/24 hr), renal impairment (serum creatinine 24.5 +/- 3.4 mumol/liter) and crescent formation (29 +/- 2% of glomeruli) were no different from =/- mice. Mouse immunoglobulin was absent in their serum and glomeruli, however, cutaneous DTH to sheep globulin was identical to heterozygous mice. These results demonstrate that glomerular crescent formation and injury can occur independent of a humoral immune response to planted glomerular antigen and without glomerular deposition of autologous antibody. This strongly supports the hypothesis that crescent formation is a manifestation of DTH.

Homozygous C2 deficiency: association with defective alternative pathway function and immunoglobulin deficiency

Deficiency in the second component of complement (C2) is the most common homozygous complement deficiency. While approximately half of the affected individuals are apparently healthy, C2 deficiency may be associated with autoimmune diseases and rarely increased susceptibility to infection. We report 5 patients who had homozygous type I C2 deficiency in two families. Three of them suffered from frequent infections. These symptomatic patients had additional risk factors; the index cases in the first and the second family had IgG2 deficiency and IgA deficiency, respectively, and alternative complement pathway hemolytic activity was also low in both of them and in the sibling of the first index case. These results emphasize the probable role of other immunologic defects in the clinical presentation of C2 deficiency.

Pneumocystis carinii infection in transgenic B cell-deficient mice

Pneumocystis carinii is an important cause of pneumonia in immunocompromised hosts. Both cellular and humoral immunity seem important in resistance to this pathogen, but the specific role of each component is poorly understood. An outbreak of P. carinii pneumonia in transgenic B cell-deficient mice (muMT) was studied. Over 4 months, >50% of 41 muMT/muMT mice maintained in a sterile environment died of pneumonia. Some mice had concurrent infection with Pasteurella pneumotropica. Homozygous muMT/muMT mice had no detectable serum immunoglobulins, while their heterozygous muMT/+ counterparts had normal levels of IgM, IgG, and IgA and did not develop pneumonia. The infection was controlled by treating the mice with trimethoprim-sulfamethoxazole, and the pathogen was eliminated by cesarean rederivation. These observations suggest an important role for B cells in the host defense against P. carinii.

DNA mutation induced in the sequence upstream of the secreted MYU C-terminal coding sequence by ultraviolet irradiation in the cell line of Bloom's syndrome

Selective IgM deficiency is commonly found in Bloom's syndrome (BS). We reported that membrane-bound mu (micron(s)) mRNA was well transcribed but secreted mu (microseconds) mRNA was not, although there was no mutation or deletion in the sequence including the microseconds C-terminal coding sequence in the patients with BS. Furthermore, we have shown previously, preferential damage to IgM production by ultraviolet (UV) irradiation of the cells of the patient. In the study described here, mutation in the sequence which is upstream of the 5' end of the microseconds C-terminal coding sequence was induced by UV irradiation in the lymphoblastoid cell line (LCL) of BS patient. These results suggest that abnormal repair of DNA damage is present in this LCL, and that preferential damage to IgM production by UV irradiation in this LCL may be due to the abnormal repair of DNA damage.

ICF syndrome with variable expression in sibs

We describe a new familial case of ICF syndrome (immunodeficiency, centromeric instability, facial anomalies) in a woman of 29 years and in her brother of 30 years. The proband showed mental retardation, facial anomalies, recurrent respiratory infections, combined deficit of IgM and IgE immunoglobulin classes, and paracentromeric heterochromatin instability of chromosomes 1, 9, and 16. The brother had minor signs of the syndrome and had an apparently normal phenotype. Their parents were healthy and non-consanguineous. Chromosome anomalies consisted of homologous and non-homologous associations, chromatid and isochromatid breaks, deletions of whole arms, interchanges in the paracentromeric region, and multibranched configurations of chromosomes 1, 9, and 16. CD bands and fluorescence in situ hybridisation with alphoid DNA sequence probes specific for the centromeres of chromosomes 1 and 16 showed that the centromere was not directly implicated in the formation of multibranched configurations. These cases indicate the autosomal recessive mode of inheritance and the variable expressivity of the ICF syndrome.

Role of x-linked immunodeficiency (xid) and NK activity in rejection of human tumor xenotransplants in nude mice

In order to elucidate the factors influencing the takes of human tumor xenografts in nude mice, we compared the transplantability of human tumors in nude mice with additional genetic defects in the immune system. The nude mice strains tested were classified as follows by expression of the beige gene and the x-linked immunodeficiency (xid) gene: 1) high NK nude (C57BL/6N, nu/nu), 2) low NK nude (C57BL/6 bg/bg nu/nu), 3) high NK nude with B-cell defect (CBA/N nu/nu), and 4) low NK nude with B-cell defect (NIH(S)III). Takes of human tumor xenografts including gastric carcinoma, T-cell lymphoma and B-cell lymphoma were better in nude mice with xid (CBA/N and NIH(S) III nude mice) than in nude mice without xid (B6 and beige nude mice). In addition, among the nude mice with xid expression, the takes were slightly better in nude mice with a CBA/N background than in those with a NIH(S) background. Moreover, the xenotransplantation rate in (CBA/N x C57BL/6N)F1 male nude mice with xid expression was higher than in (C57BL/6N x CBA/N)F1 males without xid expression, but did not react the same level as that in CBA/N nude. On the other hand, introduction of the beige gene into nude mice minimally improved the takes of human tumor xenografts under limited experimental conditions (inoculation of 100 x 10(5) T-cell lymphoma and 1 x 10(5) gastric carcinoma cells) despite the reduction of NK activity. In xenotransplantation of human tumors directly from patients, the take rates of the tumors were also better in CBA/N nude mice than in BALB/cA nude mice. The results in the present report confirmed the effect of xid and CBA/N genetic background on human tumor xenografts in nude mice, suggesting the existence of serum factors, possibly present in serum IgM, mediating rejection of the xenografts.

Familial clustering of IGHC deletions and duplications: functional and molecular analysis

The human immunoglobulin heavy chain constant region locus (IGHC) comprises nine genes and two pseudogenes clustered in a 350 kilobase (kb) region on chromosome 14q32. Several IGHC haplotypes with single or multiple gene deletions and duplications have been characterized. The most likely mechanism accounting for these unusual haplotypes is the unequal crossing-over between homologous regions within the locus. Here we report the analysis of an unusual case of familial clustering of deletions/duplications. In the two branches of the BON family, three duplicated and two deleted haplotypes, all probably independent in origin, have been characterized. The structure of the haplotypes, one of which is described here for the first time, supports the hypothesis of homologous unequal crossing-over as the origin of recombinant haplotypes. The analysis of serological markers in a subject carrying one deleted and one duplicated haplotype allowed us the first direct inferences concerning the functions of the duplicated IGHC haplotypes.

Involvement of both HLA and Ig heavy chain haplotypes in human IgA deficiency

Immunoglobulin-A deficiency (IgA-D) is the most common human Ig class deficiency with an estimated frequency of approximately 1 in 500 in the Swedish population. We investigated the immunoglobulin heavy chain constant region gene segments (IGHC) in 103 individuals with IgA-D and the immunoglobulin heavy chain variable region gene segments (IGHV) in 20 of these, in order to identify a possible molecular basis of the defect. No deletions of IGHV gene segments of the VH2, VH5, and VH6 families or the IGHG genes were observed. In the IGHC, there were, however, differences in the restriction fragment length polymorphism frequencies of IGHG genes where the Bam HI haplotype "H2" [IGHGP, 10 kilobases (kb), IGHG2, 25 kb; and IGHG4, 9.0 kb] was overrepresented. The mean serum levels of IgG4 and IgE were significantly lower in individuals (both IgA-D subjects and healthy controls) homozygous for the H2 haplotype than in individuals homozygous for the H1 haplotype (IGHGP, 8.8 kb, IGHG2, 13.5 kb, and IGHG4, 9.4 kb). IgA-D subjects homozygous for HLA DQB1*0201 (DQw2), a marker that has previously been reported to show a strong association with IgA deficiency, showed a similar reduction of serum levels of IgG4 and IgE as compared with DQB1*0201 negative IgA-D subjects. These findings suggest that the two loci found to be associated with IgA deficiency may act via a common pathway.

A familial case of hyper-IgM immunodeficiency

A 22-year-old male was diagnosed as having immunodeficiency with hyper-IgM based upon recurrent pneumonia, marked elevation of serum IgM and markedly decreased level of IgG. IgG-or IgA-bearing B cells were not detected in peripheral blood while a number and a proportion of peripheral blood T lymphocytes were normal. Peripheral blood lymphocytes from this patient proliferated normally in response to T-independent and T-dependent B cell mitogens, and to T cell mitogens. Furthermore, the same type of dysgammaglobulinemia with increased IgM was found in the patient's father and brother. From these observations, it is suggested that it is a rare case of autosomal dominant or polygenal inheritance of hyper-IgM immunodeficiency.

Selective IgA deficiency, IgG subclass deficiency, and the major histocompatibility complex

Here we have examined the connection between IgA deficiency, IgG subclass deficiency, and the absence of alleles of complement C4, and show that IgA deficient subjects who have IgG subclass deficiencies may also have an increased frequency of C4 null alleles. In our group, we found an increased incidence of HLA B38 which might reflect the ethnic composition of the patients tested. While family studies are of primary importance to assess the relationships between histocompatibility antigens and immune deficiency, these studies are complicated by the observation that C4 null alleles are not always inherited with the humoral defect.

IgG subclass deficiency with or without IgA deficiency

IgG subclass deficiency (IgGSD) is difficult to define since reference materials vary between laboratories and the clinically relevant cut off levels for the various subclasses are not well known. The diagnosis of IgGSD should be based on more than one determination since the levels vary, due to various factors such as infections, operations, etc. There is a relation between IgGSD and occurrence of frequent infections, but at the same time even total lack of a subclass can be seen in healthy individuals. Infections in the upper and lower respiratory tract predominate. Gm allotypes influence IgG subclass levels. Most IgGSD patients are homozygous in the Gm system. Immunocytes producing IgG3 in the nasal mucosa correlate with serum IgG3 levels, whereas rectal IgG1 producing cells relate to serum IgG1 levels. This may reflect differences in antigen and/or mitogen exposure at the two mucosal sites. IgG2SD is the predominant form of IgGSD among children, whereas after puberty IgG3SD is most common. At the same age period there is a switch in sex distribution from three boys/one girl to one male/three females. Various abnormalities in B and T lymphocyte numbers and function are often found. In a double blind crossover study of Ig prophylaxis over 2 years in 43 IgGSD adult patients a significant decrease in the number of days with infections was seen both in the whole group and among the IgG1 deficient. Days with bronchial constriction were also significantly decreased among the 22 patients who had asthma as well. Acute bronchitis became significantly less frequent in the IgG3 deficient patients during Ig prophylaxis. This was seen in those under the lower range of 0.41 g/liter of Oxelius' early normal material, although many recent reference materials suggest 0.14-0.15 g/liter of IgG3 as the cut off. In a group of 25 consecutive patients with IgGSD + IgA deficiency recurrent respiratory infections were the major problem and lung function impairment was found in 12, and bronchiectasies in 5. Still many individuals with this combined deficiency have been reported to be healthy, again illustrating our limited understanding of these conditions.

Clinical manifestations in selective IgA deficiency in childhood. A follow-up report

Clinical manifestations in 40 children with selective IgA deficiency were studied during a follow-up period of 2-10 years. The patients were divided into two groups: group I consisted of 25 children with "sporadic" IgA deficiency and group II of 15 children with "familial" IgA deficiency. Respiratory tract infections including otitis media were frequent in both groups. Concomitant IgG2-IgG4 deficiency was found in two patients in group I. Longitudinal serum IgG levels were elevated significantly in both groups. Atopic complaints were observed in 10 children of the "sporadic" group, but only in two of the "familial" group. However, elevated serum IgE levels were more often found in group II. Two children of group I were mentally retarded and chromosomal examination showed abnormalities in both. Anti-IgA antibodies were detected in one child in group I and three children in group II. These three patients had an IgA deficient mother with class-specific anti-IgA antibodies. Concomitant IgG4-IgE deficiency was found in all four.

[Primary immune deficiencies of B-lymphocytes]

Primary B-cell immunodeficiency is relatively frequent and may result in recurrent bacterial infections involving notably the respiratory tract, and in chronic severe enteroviral infections in patients with agammaglobulinaemia. Selective IgG2 isotype deficiency results in pneumococcal, Haemophilus influenzae and pseudomonal infections, since it is associated with defective production of antibodies that are specifically directed against bacterial capsular polysaccharides. Progress has recently been achieved in the determination of genetic and molecular bases of some of these immunodeficiencies. In X-linked agammaglobulinaemia, the abnormal gene has been located on the long arm of the X chromosome (Xq22-23); the intrinsic B-cell abnormality blocks differentiation at the pre-B stage, before the genes coding for light chain immunoglobulins are rearranged. There is now a strong suspicion that IgA deficiency, hypoglobulinaemia with variable expression and some selective IgG isotype deficiencies are three ways of expressing one single abnormality a genetic factor of which is located in the class III region of the HLA complex and perhaps also associated with HLA class II DQ. Treatment of deficient IgG production with intravenous immunoglobulin has thoroughly altered the prognosis of these diseases. Complete IgA deficiency carries a risk of accident by production of anti-IgA antibodies, which means that patients with isolated IgA deficiency should not be treated, that these antibodies should systematically be looked for in patients with IgA deficiency associated with partial deficiency of other immunoglobulins, and that these patients should be treated with IgA-free immunoglobulin preparations.

Frequencies of interleukin-5 mRNA-producing cells in healthy individuals and in immunoglobulin-deficient patients, measured by in situ hybridization

Interleukin-5 (IL-5) has previously been demonstrated to enhance immunoglobulin synthesis, especially IgA. Thus, it could be hypothesized that a defect production of IL-5 may cause immunoglobulin deficiency. We have analysed the frequency of IL-5 mRNA-producing cells in healthy adults and in patients with common variable immunodeficiency or selective IgA deficiency. Unstimulated lymphocytes were rarely found to synthesize IL-5 as measured by in situ hybridization. However, pokeweed mitogen and several other activating ligands induced the synthesis of IL-5 mRNA in peripheral blood and spleen lymphocyte cultures. After pokeweed mitogen activation, the number of IL-5 mRNA-producing cells most often peaked on day 3 with a maximal frequency of around 1-2% of mononuclear cells. In a kinetic study we were unable to detect any peak frequency differences between healthy controls (mean 0.44%) and 20 patients (mean 0.58%). Thus, although IL-5 has been reported to be an important regulator of IgA synthesis, a defect production does not seem to be the underlying mechanism in human immunoglobulin deficiency.

Lack of the G2m(n) allotype in IgG subclass deficiency, in IgG2 deficiency together with lack of G1m(a) and G3m(g), and in IgG3 deficiency together with lack of G1m(f) and G3m(b)

Lack of G2m(n) was demonstrated in both IgG2-deficient and IgG3-deficient Caucasian patients. Lack of G2m(n) or G2m(",") was found together with homozygosity for both G1m and G3m allotypes as the dominant finding, i.e. for IgG2-deficient patients together with G1m (f,f) and G3m(b,b), constituting the Gm(f,",b) phenotype, and for IgG3-deficient patients together with G1m(a,a) and G3m(g,g), constituting the Gm(a,",g) phenotype. The group with IgG2 deficiency and the selected patients with the Gm(f,",b) phenotype expressed characteristically very low or undetectable IgG4, significantly increased IgG3, and normal IgG1. The group with IgG3 deficiency and the selected patients with the phenotype Gm(a,",g) expressed instead normal IgG4 and nearly normal IgG2 and IgG1 levels. The lack of G2m(n) together with lack of one or the other of the alternative G1m genes and corresponding G3m genes give different IgG2 levels and different IgG subclass patterns. The frequency of G1m allotypes and corresponding G3m allotypes also deviated significantly when the IgG2 deficiency and IgG3 deficiency groups were compared with each other. Most IgG subclass-deficient patients are homozygous in the Gm system and lack genetic variants in the three IgG subclasses, IgG1, IgG2, and IgG3.

Genetic aspects of immunoglobulin A deficiency

IgA deficiency is one of the most common of all immune defects. While it is often not associated with clinical illness, presumably due to compensation from other sectors of the immune system, IgA-deficient individuals are distinctly more likely to become ill and have one or more of specific groups of diseases. While the unifying immunologic perturbation in IgA deficiency is a lack of mature IgA-secreting B cells, a host of other, usually minor, immunologic abnormalities have been reported in such patients. IgA deficiency can be inherited in an autosomal dominant or autosomal recessive fashion, but most individuals who are IgA deficient have no other affected family members. From a genetic point of view, IgA deficiency has been associated with three chromosomes, 18, 14, and 6. Many IgA-deficient individuals who have cytogenically detectable abnormalities of chromosome 18 have been reported, but all the individuals with these defects have severe congenital defects of other kinds. Obscuring the relationship between chromosome 18 and IgA deficiency is the fact that both short- and long-arm deletions have been reported in IgA deficiency. The chromosome deletions in the individuals who are IgA deficient thus appear to have no common pattern. While a rare individual can be IgA1 deficient on the basis of heavy-chain deletions of alpha 1 genes in concert with other heavy-chain genes on chromosome 14, such individuals are quite rare, and from a clinical point of view, those reported have usually been healthy. Absence of both IgA1 and IgA2 genes (presumably in concert with other heavy-chain genes) has never been reported. For chromosome 6, a more complex puzzle emerges. IgA-deficient individuals have been reported to have one of a few specific HLA haplotypes. While many individuals with these supratypes are not IgA deficient, these findings encourage the notion that the secretion of IgA could be at least partly controlled by genes residing in the major histocompatibility locus.

Selective IgG deficiency with a transcriptional disorder of the gamma switching region gene and the IL-4 gene

A primary immunodeficiency patient was analysed whose serum IgG and IgE were extremely low but whose IgM and IgA levels were within the normal range or elevated. Southern blot analysis indicated no deletion of structural genes coding for C gamma, C epsilon, or C alpha. The majority of the patient's peripheral B cells expressed IgM and IgD on the surface yet IgG-positive B cells were not detected, suggesting that the defect is in a switch-recombination process from IgM to IgG. The RFLP pattern detected with the S mu and S gamma DNA regions revealed that there was no deletion or large mutation in the switch region DNA. An in vitro IgG production system with pokeweed mitogen showed an abnormality at the transcriptional level and the defects were in both the patient's T and B cells. Addition of recombinant IL-4 (rIL-4) to the normal B cells enhanced IgG production but the patient's B cells did not respond to rIL-4, although the IL-4 receptor was present at the normal level. Messenger RNA and IL-4 protein were not produced in the patient's T cells upon stimulation with phorbol ester and calcium ionophore, whereas IL-2 was normally produced. The patient's lymphocytes showed a proliferative response to various mitogens, including phorbol ester. The transcripts of unrearranged C gamma region genes were not detected in the patient's lymphocytes, suggesting that the chromatin structure of the S gamma region may not be open. These results suggest that the transcriptional defects at the S gamma region gene in B cells and at the IL-4 gene in the T cells may be responsible for the present IgG immunodeficiency. There might be a common transcriptional system operating in a certain step in the activation of both genes.

Theiler's virus-induced demyelination in mice immunosuppressed with anti-IgM and in mice expressing the xid gene

Intracerebral infection with Theiler's murine encephalomyelitis virus produces chronic immune-mediated demyelination in susceptible strains of mice. We examined the role of Ig in the pathogenesis of demyelination. In susceptible SJL/J mice (H-2s), suppression of B cell responses with IgG fraction of goat anti-mu (anti-mu IgG) from birth resulted in increased numbers and severity of demyelinating lesions in the spinal cord 35 days after infection. In contrast, treatment of resistant C57BL/10 (H-2b), C57BL/6 (H-2b), or B10.D2 (H-2d) mice with anti-mu IgG had no apparent effect since these mice did not develop demyelination or inflammation in the spinal cord following infection. Similar results were obtained with certain strains of B-cell deficient mice that exhibit the xid gene mutation. Male CBA/NJ (xid) showed increased meningeal inflammation and demyelination compared to male CBA/J mice. However, B6.CBAN, C3.CBAN, or C.CBAn mice showed no or minimal evidence of demyelination despite the presence of the xid mutation. In the SJL/J mouse, the majority of the humoral immune response to virus antigen was restricted to the IgG2b and IgM isotypes. These data indirectly support the hypothesis that immunoglobulins protect partially against development of virus-induced demyelination in susceptible but not resistant animals. In addition, the data argue strongly against the hypothesis that TMEV-induced demyelination is mediated predominantly by humoral autoimmune or humoral viral immune mechanisms.

Individuals with IgA deficiency and common variable immunodeficiency share polymorphisms of major histocompatibility complex class III genes

IgA deficiency and common variable immunodeficiency are heritable disorders that can occur within the same family. Both immunodeficiencies are characterized by arrests in B-cell differentiation that vary in the extent of the immunoglobulin isotypes involved. A high frequency of major histocompatibility complex supratypes associated with a null allele of the gene encoding the C4A isotype of complement component C4 has been observed in IgA-deficient individuals. In search of a genetic linkage between the two immunodeficiencies, we examined the major histocompatibility complex (MHC) class III genes encoding complement components C2, C4A, and C4B and steroid 21-hydroxylase in addition to the HLA serotypes in individuals with either common variable immunodeficiency or IgA deficiency. Twelve of 19 patients with common variable immunodeficiency (63%, P less than 0.001) and 9 of 16 patients with IgA deficiency (56%, P less than 0.01) had rare C2 alleles and/or C4A and 21-hydroxylase A deletions, whereas these gene features were seen in only 5 of 34 healthy individuals (15%) in the control group. Nine of 11 patients with C4A deletion had an HLA haplotype consistent with the MHC supratype HLA-A1, Cw7, B8, C4AQ0, C4B1, BfS, DR3 previously found to be associated with IgA deficiency. The data support the hypothesis that common variable immunodeficiency and IgA deficiency are related disorders, susceptibility to which is determined by a gene(s) within or near the MHC class III gene region on chromosome 6.

Familial IgE deficiency associated with sinopulmonary disease

Three generations of relatives of 58-year-old nonidentical twins with chronic bronchitis and fibrotic lung disease were evaluated. Sera of 23 family members, 14 with a history of excessive sinopulmonary infections, were examined for deficiencies of immunoglobulin classes, IgG subclasses, and specific antibody to tetanus toxoid and Hemophilus influenzae type b. Of 14 symptomatic family members, 12 had serum IgE concentrations less than 5 IU/ml. Four had values less than 1 IU/ml. Serum IgE was greater than 10 IU/ml in all nine asymptomatic individuals. Inheritance of low IgE appeared to be autosomal dominant, with variable penetrance. IgA was low normal (70-90 mg/dl) in three individuals. Two of these were IgE deficient. One symptomatic child had unmeasurable IgG2 (less than 10 mg/dl) and IgE (less than 0.5 IU/ml). This kindred demonstrates that IgE deficiency can be familial, and associated with sinopulmonary disease.

Myelodysplastic syndrome with trisomy 8 in an adolescent with Fanconi anaemia and selective IgA deficiency

We describe a patient with growth failure and multiple congenital anomalies characteristic of Fanconi anaemia, but without the classical feature of progressive bone marrow hypoplasia. Following treatment with growth hormone for a period of 8 years, he presented with myelodysplastic syndrome and a karyotypically abnormal clone in the bone marrow (47,XY,+8). The diagnosis of Fanconi anaemia was supported by the induction of abnormally high levels of characteristic chromosome aberrations in peripheral lymphocytes following exposure in vitro to the bifunctional alkylating agent mitomycin C. Immune function studies also identified a selective IgA deficiency. The relative importance of interacting constitutional and exogenous factors involved in the development of preleukaemia in this patient is discussed.

Detection of an alteration of the alpha 2-macroglobulin gene in a patient with chronic lung disease and serum alpha 2-macroglobulin deficiency

alpha 2-Macroglobulin (A2M) is a major human plasma protease inhibitor capable of inhibiting most endopeptidases tested so far. In the case of the other major plasma protease inhibitor, alpha 1-antitrypsin, genetically determined deficiency states are known to increase the risk of chronic obstructive pulmonary disease (COPD) 20- to 30-fold in affected individuals. No defects of the A2M gene have been described as yet, but A2M may play a role in the regulation of protease activity in the lung, especially with respect to those proteases not inhibited by alpha 1-antitrypsin. We report here the molecular genetic detection of an alteration of the A2M gene in a patient with serum A2M deficiency and chronic lung disease since childhood. The alteration involves restriction sites detected with 10 different enzymes and is most probably caused by a major deletion or rearrangement of the gene. Nine of the restriction enzymes used detected no polymorphisms in 40 healthy control subjects and 39 COPD patients. The polymorphism detected in this patient with the enzyme PvuII was different from another described previously, and was found in this patient only. The patient is heterozygous for an alteration in the A2M gene; this may be responsible for his serum A2M deficiency and may be relevant to the early onset of pulmonary disease in his case.

Recurrent extended HLA haplotypes in children with selective IgA deficiency

HLA supratypes as well as serum IgG, IgA and IgM levels were determined in 44 children and adolescents with severe IgA deficiency (serum IgA less than 5 mg/dl) and in first degree relatives. Frequencies of the HLA alleles B14, DR1, DQW1, C4A2 and C4B2 were significantly higher in the IgA-deficient patients than in the controls. The most recurrent haplotype among patients was B14, DR1 (p less than 10(-4) preferentially associated with A33, A28 or A blank. The supratype B14, Bfs, C4A2, C4B2, DR1, DQW1 was present in a 14-fold higher frequency than in the controls, and strongly suggests the presence of a gene in the HLA region involved in the deficiency of IgA. The fact that this supratype was not always associated with IgA deficiency in the parents and that not all IgA-deficient subjects had this supratype is discussed. Severe IgA deficiency was found in four mothers (two of the four mother-child pairs shared the B14, DR1 haplotype); three other relatives (one father and two brothers) had partial IgA deficiency and did not have the B14, DR1, DQW1 haplotype.

Molecular and serologic analysis of IgG1 deficiency caused by new forms of the constant region of the Ig H chain gene deletions

Selective IgG1 deficiency is a rare disease. We report a familial form of IgG1 deficiency, in which IgG1 was undetectable in a 5-yr-old girl with a history of asthma and respiratory tract infections. Her father had an IgG1 level that was one-third of the mean amount found in normal healthy controls. The defect in the proband was caused by a homozygous deletion of the structural gene for C gamma 1. A Southern blot analysis demonstrated that the maternal haplotype contained a deletion encompassing C gamma 1, C psi epsilon 1, C alpha 1, C psi gamma, and C gamma 2, whereas the deletion on the paternal haplotype was confined to the C gamma 1 gene. Neither of these deletions has previously been reported. IgG1 normally constitutes the dominant isotype for antibodies directed against protein Ag, including viral proteins. We have analyzed the immune response to a number of different protein and polysaccharide Ag in the patient and her parents. In the proband, antiviral antibodies were restricted to the IgG3 and IgG4 subclasses. However, the total amount of IgG directed against several viruses was below the concentration found in normal seropositive individuals. The father and the paternal grandfather, both with low serum IgG1 levels, also had asthma, thus indicating a possible causal relationship.

[Pathogenesis of spontaneous hepatitis in an inbred strain of LEC (Long Evans cinnamon) rats]

We have reported an inbred strain LEC rats with high frequency of spontaneous hepatitis. In this paper, we study a possible involvement of hepatitis virus, hereditary background, and correlation between serum IgG level and onset of hepatitis in LEC rats. Neither electron microscopy nor indirect immunofluorescent test could detect hepatitis virus article or antigen. Furthermore, we could not succeed in inducing hepatitis of LEA and WKA/H rats by injecting the serum, plasma and liver homogenates of the affected IEC rats, nor in promoting/developing hepatitis of LEC and LEA rats under the immunosuppressed condition by administration of steroid hormone. When we made a mating between LEC and non-hepatitis rats to investigate the hereditary mode, F1s had no hepatitis, but F2s and backcrosses developed hepatitis. We observed, in particular, the lower the serum IgG level was, the higher the rate of developing hepatitis was. From these results, we speculate that the involvement of hepatitis virus is not likely, but that a genetic mutation might cause low level of IgG and be also correlated with development of hepatitis.

Human immunoglobulin G and immunoglobulin G subclasses: biochemical, genetic, and clinical aspects

Human IgG consists of two identical heavy (H) chains and two identical light (L) chains joined by interchain disulfide bridges. Heterogeneity in the amino acid sequences of the H and L polypeptides results in at least three types of IgG variants at the structural and genetic levels. The four isotypic forms are IgG1, IgG2, IgG3, and IgG4, which share extensive homologies in the primary structure of their H chains. As a result, the subclasses cross-react antigenically, but they can be differentiated on the basis of subtle architectural dissimilarities. The biological and effector properties of the IgG isotypes have been associated, in part, with their structural differences. Genes determining the synthesis of human IgG heavy chains are located on chromosome 14. In several clinical situations the isotypes appear to be regulated or expressed in patterns reflecting the gene arrangement. The numeric designations of the subclasses correspond to the order of their proportional amounts in healthy adult serum: IgG1 greater than IgG2 greater than IgG3 greater than IgG4. Awareness of the importance of the roles of the four IgG isotypes in human health has steadily increased since they were first described in the 1960s. The recognition that deficits or increases in selected IgG subclasses may have clinical consequences has prompted considerable interest in quantifying the four isotypes in clinical specimens. In particular, deficiencies of IgG2, IgG3, and IgG4, singly or combined, are associated with chronic infections which may not be readily recognized in otherwise healthy people with normal serum total IgG concentrations. Different assay methods using polyclonal or monoclonal antisera with various calibrants have been applied; however, no standardized method exists at the present. IgG deficits are associated with gene defects and are acquired in secondary immunodeficiencies in conjunction with other disorders. IgG isotype selectivity has been recognized in autoimmune diseases and in response to carbohydrate and protein antigens derived from pathogenic microorganisms and common allergens.

Immunoglobulin subclass deficiency

IgG subclass deficiency was first noted in 1968. Subnormal levels of one or two, occasionally three IgG subclasses may be relatively common. It has not been determined, however, at what level below the normal range the IgG subclass deficiency is of clinical relevance. It remains important to clarify this point because certain subclass deficiencies may be without relevance of their own. Because patients with decreases of various IgG subclasses often present with a number of diseases, the low immunoglobulin levels may signify the presence of other abnormalities of more biologic significance. IgG subclass deficiency has been noted in about 25% of patients with well-defined food allergy and in patients with asthma, diabetes mellitus, Henoch-Schönlein's purpura, Bechterew's disease, intractable epilepsy of childhood, Friedreich's ataxia and autoimmune cytopenias. Most commonly they have increased frequency of infections especially in the respiratory tract, including sinusitis, otitis media and bronchopneumonia, but also osteomyelitis, meningitis, septicemia and various skin infections. Low levels of various subclasses have been noted in connection with other immunodeficiencies such as ataxia-telangiectasia. In common variable immunodeficiency there is an obvious imbalance in the IgG subclasses. Furthermore IgG subclass deficiency can be seen in relatives of patients with common variable immunodeficiency and in IgA deficiency. They also occur in relatives of patients with systemic lupus erythematosus, diabetes mellitus type 1 and C2 deficiency. In a few cases of subclass deficiency gene deletions have been shown. Subnormal levels of IgG subclasses make a remarkable change in sex distribution around puberty from 3/1 in boys and girls to the reverse sex ratio among adults.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for linkage of IgA deficiency with the major histocompatibility complex

A 57-year-old woman with IgA deficiency and Still's disease was the proband in a 20-member, three-generation kindred in which we studied the possible linkage of IgA deficiency with her HLA-A1-B8 haplotype. The presence of paternal A1-B8 haplotype complicated the analysis. Known maternal HLA-A1-B8 haplotype, present in three of the children of the proband, was associated with IgA deficiency, whereas all five family members with exclusively paternal A1-B8 had normal IgA. Of three third-generation family members whose A1-B8 haplotype was of indeterminate origin--that is, potentially either maternally or paternally derived--two had IgA deficiency and one did not.

Subclass restriction pattern of antigen-specific antibodies in donors with defective expression of IgG or IgA subclass heavy chain constant region genes

We have developed a method for the measurement of the IgG and IgA subclass distribution of antigen-specific human antibodies. The controls for the specificity of the assay include the use of a number of monoclonal human antibodies and sera from individuals with deletions of particular immunoglobulin heavy chain constant region genes. The system was used to determine the shift in immunoglobulin subclass patterns of specific antibodies against a variety of protein and polysaccharide antigens in individuals with a regulatory deficiency of a given IgG or IgA subclass. Normally, the pattern is quite distinct and antibodies against protein antigens are mainly of the IgG1 subclass, whereas antibodies against polysaccharide antigens are mainly of the IgG2 subclass. The results on serum from an IgG1 deficient donor suggested that IgG3 and IgG4 appear to compensate for a lack of IgG1, whereas isolated deficiencies of IgG3, IgG4, or IgA2 do not markedly influence the expected distribution of specific antibodies. In IgG2-deficient individuals a more complex pattern was observed where antibodies against protein antigens were retained, whereas levels of antibodies against polysaccharide antigens could vary markedly between donors, which appeared to be dependent on whether the IgG2 deficiency was an isolated defect or combined with IgG4/IgA deficiency. However, all the IgG2-deficient donors had a skewed pattern of anti-polysaccharide antibodies with a shift to IgG1 to IgG3.

Successful treatment of echovirus meningoencephalitis in sex-linked agammaglobulinaemia by intrathecal and intravenous injection of high titre gammaglobulin

A 7-year-old boy with sex-linked agammaglobulinaemia developed meningoencephalitis caused by echovirus type 11. He had convulsions, right hemiplegia, cortical motor aphasia, left abducens nerve paralysis, left hypoglossal nerve paralysis, and later became unconscious. Treatment by intravenous injection of conventional gammaglobulin and intrathecal alpha-interferon brought no clinical improvement, but intrathecal administration together with intravenous injection of gammaglobulin containing a high titre of anti-echovirus type 11 antibody was associated with a dramatic improvement in his clinical symptoms. After subsequent periodical (once or twice a week) administration of specific gammaglobulin for 8 months, the echovirus in his cerebrospinal fluid was no longer detected. These findings suggest that intrathecal injection combined with intravenous injection of high titre anti-echovirus type 11 antibody was effective in treating this case of echovirus meningoencephalitis in sex-linked agammaglobulinaemia.

Chromosome studies in IgA-deficient patients

Chromosome analysis was performed in 17 children with IgA-deficiency. In two patients a constitutional structural chromosome abnormality was found. A ring chromosome 22 was seen in one, while in the other a mosaicism of ring chromosome 18/18p+ was observed. Both patients were mentally retarded and showed distinct congenital defects. From ten asymptomatic patients, spontaneous as well as X-ray-induced chromosome instability was investigated. There was no increased spontaneous instability, and also after irradiation the induced chromosome damage was within normal control levels. A relationship between IgA-deficiency and X-ray hypersensitivity, as might be suggested by the frequently occurring coincidence of radiosensitivity and IgA-deficiency in ataxia telangiectasia patients, is not established.

IgA2 allotypes determined by restriction fragment length polymorphism in IgA deficiency. Re-expression of the silent A2m(2) allotype in the children of IgA-deficient patients

IgA2 allotyping was performed on DNA from 60 IgA-deficient Caucasian individuals. The frequency of A2m(2) was not statistically different from that of normal controls. Two informative families were selected for further studies. In both families, the A2m(2) allotype (derived from the IgA-deficient parent) was inherited by some of the children, as determined by Southern blotting experiments. In all cases the 'silent' IgA2m2 gene was re-expressed, as judged by conventional serological allotyping of serum proteins. These data strongly argue against structural gene deletions or mutations as a cause of IgA deficiency.