Estimation of the time-dependent vaccine efficacy from a measles epidemic.

We present a method to estimate the time-dependent vaccine efficacy from the cohort-specific vaccination coverage and from data on the vaccination status of cases and apply it to a measles epidemic in Germany which involved 529 cases, 88 of whom were vaccinated and 370 unvaccinated (for the remaining 71 cases the vaccination status is unknown). Our epidemiological model takes into account that maternal antibodies prevent successful vaccination and that vaccine immunity may be lost over time. Model parameters are estimated from the data using maximum likelihood. Vaccination coverage, as determined in school surveys, ranged from 27.6 per cent for the cohort born in 1974 to 85 per cent for the 1986 cohort, which is far too low to prevent measles transmission. Cohorts for which no school surveys were performed are omitted from analysis. Thus, sufficient data are available for only 282 cases, 69 of whom are vaccinated. According to our estimates, measles vaccinations provided no immunity before 1978 (95 per cent CI: 0 to 47 percent), for the period 1978-1982, the estimated vaccine efficacy was 80 percent (95 percent CI: 67 to 89 percent), and for 1982-1990 it was 97 percent (95 percent CI: 93 to 99 percent). After 1990, the estimated value dropped to 89 per cent, but its confidence interval widely overlaps with that of the previous period (95 percent CI: 74 to 97 percent). Loss of immunity was estimated to be zero (95 percent CI: 0 to 0.003/year). Several sensitivity analyses were performed with respect to the model assumptions. A modified model which assumed constant efficacy at all vaccination times yielded a high estimate of 96 per cent (95 percent CI: 92 to 98 percent) for primary vaccine efficacy but also a high loss rate of immunity of 0.007/year (95 percent CI: 0.001 to 0.012) to explain the high fraction of vaccinated cases among older individuals. The likelihood score value is however significantly inferior compared to the score value of the model with time-dependent vaccine efficacy.

Autoimmune lymphoproliferative syndrome associated with severe humoral immunodeficiency and monoclonal gammopathy.

A boy of Caucasian origin with a new subtype of autoimmune lymphoproliferative syndrome (ALPS) is described. The clinical picture was dominated by chronic noninfectious lymphadenopathy, splenomegaly, and recurrent bacterial infections. At the age of 6 the patient died of pneumococcal meningitis. Laboratory investigation disclosed impaired apoptosis in both B- and T-lymphocyte subsets and expanded populations of CD3+CD4-CD8- T lymphocytes. Furthermore, marked dysregulation of humoral immune responses with transient expansion of monoclonal B cells, corresponding monoclonal gammopathy, and the presence of autoantibodies was found. Functional and molecular analysis revealed that Fas protein expression was normal, a mutation in the Fas gene was not found. Moreover, transcription of the downstream effector caspase-10 was unremarkable. This patient is unique compared to previously described patients as severe humoral immunodeficiency and monoclonal gammopathy are usually not described in patients with ALPS. This case points out the important role of apoptosis in regulating the degree of humoral immune responses at a clonal level in humans and gives further evidence for the phenotypic diversity of ALPS.

Periodic fever (TRAPS) caused by mutations in the TNFalpha receptor 1 (TNFRSF1A) gene of three German patients.

TNF-receptor-associated periodic syndrome (TRAPS) is a recently recognized disorder characterized by prolonged attacks of high fever and severe localized inflammation. TRAPS is caused by dominant mutations in the 55 kDa TNF receptor gene (TNFRSF1A). We here describe three German TRAPS patients of two families with Cys30-->Arg and Thr50-->Met mutations, respectively. Both mutations have already been observed before in other nonrelated families. The Thr50-->Met amino acid exchange, caused by an ACG-->ATG transition, has been reported in two other families of different ethnic background. The possibility that the ACG-->ATG sequence alteration is a mutational hot spot causing TRAPS is discussed. Furthermore, we describe and discuss the symptoms of our patients, possible inducers of febrile attacks, and treatments which the patients had received when their diagnoses were still unknown.

Acute and long-term effects of booster immunisation on frequencies of antigen-specific memory B-lymphocytes.

In search for a parameter that is predictive of long-term immunity, we analysed the influence of booster immunisations on frequencies of circulating memory B-lymphocytes. Specific IgG-secreting B-cells were determined by ELISPOTassay in 13 healthy adults, using diphtheria and tetanus toxoid as model antigens. Our results show that memory B-cells accumulate with every immunisation dose and remain elevated over several years. In addition, secondary B-cell responses were studied during the first 90 days after diphtheria re-immunisation. A significant indirect correlation was found between the number of previous boosters and the magnitude of specific B-cell expansion. In contrast, effects of booster immunisations did not correlate likewise with antigen-specific serology. Hence, this study illustrates that frequencies of antigen-specific B-lymphocytes can be used as an indirect measure for immunological memory. This parameter could be helpful to find scientifically based immunisation strategies for currently available and novel vaccines.

Homozygous and compound-heterozygous type I plasminogen deficiency is a common cause of ligneous conjunctivitis.

Severe type I plasminogen deficiency has been recently linked to ligneous conjunctivitis, a rare and uncommon form of chronic conjunctivitis. In this study, eight unrelated ligneous conjunctivitis patients living in different parts of the world were examined. All affected subjects from which plasma was available displayed absent or markedly reduced plasminogen antigen and plasminogen functional activity. Molecular genetic studies of seven patients identified a Lys19-->Glu mutation in two boys in a homozygous state, and in two girls in a compound-heterozygous state in which the second plasminogen gene carried a missense (Arg134-->Lys) and a nonsense mutation (Cys133--> Stop), respectively. A fifth patient was shown to be homozygous for a frameshift mutation in plasminogen exon 14 (Gly565ins-G). In two unrelated subjects with ligneous conjunctivitis no mutations in the plasminogen gene were identified. Our results suggest that the Lys19-->Glu mutation is the most prevalent mutation in the plasminogen gene of patients with ligneous conjunctivitis.

Lethal pneumococcal infection in an 18-month-old girl with splenic hypoplasia and dysgammaglobulinemia.

We report the case of an 18-month-old girl who died of overwhelming pneumococcal sepsis. Autopsy revealed a small spleen with unusual architecture. There was a marked rarefaction of the white pulp with only very few but florid germinal centers. Immunohistochemical staining showed a low number of T and B lymphocytes in the spleen, whereas normal numbers and distribution of lymphocytes were found in all other primary and secondary lymphatic organs. Whereas levels of IgM were normal, IgA and IgG levels were significantly lower than in age-matched controls. Consistent with serological data, B cells mainly expressed IgM and IgD, whereas IgG expression was lower than expected. Additionally, intestinal immunoglobulin distribution in B-cell areas of lymphofollicular hyperplasia showed normal expression of IgM, but almost no expression of IgA. A review of the literature failed to disclose a similar case of dysgammaglobulinemia associated with isolated structural spleen anomalies. We propose that the patient suffered from a defect of the B-cell differentiation pathway.

Limited sequence heterogeneity of Epstein-Barr virus nuclear antigen 1 in benign and malignant EBV-associated disorders.

BACKGROUND: The Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA-1) is essential for replication and maintenance of circular EBV genomes in latently infected B lymphocytes and is the only EBV protein expressed in nearly all cells carrying the virus. EBNA-1 is suggested to be oncogenic in vivo since its expression induces B-cell neoplasia in transgenic mice. PATIENTS, MATERIALS AND METHODS: EBV wild-type isolates from ten malignant tumors and from 15 children with various benign EBV-associated disorders were examined for the presence of EBNA-1 variant strains by PCR and sequencing. RESULTS: One isolate harbored both the B95-8-like and a variant sequence within the C-terminus of the EBNA-1 gene. All other isolates (n = 24) revealed clustered nucleic acid sequence alterations within the EBNA-1 gene, which led to amino acid exchanges at positions 524, 563, 574, 585, 594 and 595. Few isolates exhibited additional amino acid exchanges at positions 564, 571 or 588. CONCLUSIONS: The observed EBNA-1 sequence variation pattern seems not to be restricted to a certain EBV-associated disease or tumor type. The EBNA-1 variant strains reported here may reflect the most prevalent EBV strains in the exposed population. In none of all the cases studied so far did the sequence alteration affect any known functionally crucial amino acids in the core domain of EBNA-1. This suggests that strict conservation of most of the C-terminal portion of EBNA-1 sequence may be essential for survival of EBV in the infected host.

A novel sensitive approach for frequency analysis of measles virus-specific memory T-lymphocytes in healthy adults with a childhood history of natural measles.

Measles virus (MV), a single-stranded negative-sense RNA virus, is an important pathogen causing almost 1 million deaths annually. Acute MV infection induces immunity against disease throughout life. The immunological factors which are responsible for protection against measles are still poorly understood. However, T-cell-mediated immune responses seem to play a central role. The emergence of new single-cell methods for quantification of antigen-specific T-cells directly ex vivo has prompted us to measure frequencies of MV-specific memory T-cells. As an indicator for T-cell activation IFN-gamma production was measured. PBMC were analysed by intracellular staining and ELISPOT assay after stimulation with MV-infected autologous B-lymphoblastoid cell lines or dendritic cells. T-cell responses were exclusively seen with PBMC from MV-seropositive healthy adults with a history of natural measles in childhood. The median frequency of MV-specific T-cells was 0.35% for CD3(+)CD4(+) and 0.24% for the CD3(+)CD8(+) T-cell subset. These frequencies are comparable with T-cell numbers reported by other investigators for persistent virus infections such as Epstein-Barr virus, cytomegalovirus or human immunodeficiency virus. Hence, this study illustrates that MV-specific CD4(+) and CD8(+) T-cells are readily detectable long after the acute infection, and thus are probably contributing to long-term immunity. Furthermore, this new approach allows efficient analysis of T-cell responses from small samples of blood and could therefore be a useful tool to further elucidate the role of cell-mediated immunity in measles as well as in other viral infections.

X-linked lymphoproliferative disease is caused by deficiency of a novel SH2 domain-containing signal transduction adaptor protein.

X-linked lymphoproliferative disease (XLP) is an inherited immunodeficiency, involving primarily T and natural killer (NK) cells, which in the majority of cases exacerbates following exposure to Epstein-Barr virus (EBV). Prior to EBV infection, most boys with the defective XLP gene appear to be clinically healthy EBV infection in males with the defective XLP gene leads to three main phenotypes: severe and mostly fatal infectious mononucleosis (58%), lymphoproliferative disorders mostly of B-cell origin (30%) and/or dysgammaglobulinemia (31%). Later in life, dysgammaglobulinemia and malignant lymphoma may also develop in about 53% and 56% of EBV-negative XLP males, respectively This fact suggests that EBV may only act as a potent trigger of the earliest and most serious clinical phenotype of XLP, i.e. fatal infectious mononucleosis. XLP has an unfavorable prognosis. Successful transplanta tion of hematopoietic stem cells can cure this immunodeficiency In the future, gene therapy may eventually become an additional option to prevent XLP. The gene responsible for XLP, SH2-domain containing gene 1A (SH2D1A) has recently been identified and sequenced. SH2D1A encodes a polypeptide of 128 amino acids containing a single SH2 domain. Until now, 45 different SH2D1A gene mutations have been identified in patients with XLP SH2D1A is thought to play an important role in signal transduction in T and NK cells. In vitro, SH2D1A has been shown to interact as an adaptor protein with the signaling pathways through SLAM, a T-cell co-stimulatory molecule, and 2B4, an NK-cell-activating receptor. Further functional studies of the SH2D1A protein will probably provide new insights into the pathogenesis of severe infectious mononucleosis, malignant lymphomas and immunodeficiency in patients with XLP.

Combination of von Willebrand disease type 1 and partial factor XII deficiency in children: clinical evidence for a diminished bleeding tendency.

Factor XII deficiency can be associated with a thrombotic and VWF deficiency with a haemorrhagic clinical course. To study the potential influence of factor XII deficiency on bleeding tendency in patients suffering from VWD we retrospectively compared the clinical outcome of children with either an isolated factor XII deficiency, an isolated VWD, or a combination of both. Patients with the combined coagulation defect showed significantly fewer bleeding events when compared to patients with isolated VWD, although ristocetin cofactor activities were reduced to a comparable degree. As far as aPTT values are concerned, there were no significant differences among the three groups. Whether this combination of thrombophilic and haemorrhagic coagulation disorders is only coincidental or the result of an active modulation of one of the two counteracting coagulation factors is not known at present.

Reversible monoclonal lymphadenopathy in autoimmune lymphoproliferative syndrome with functional FAS (CD95/APO-1) deficiency.

The FAS (CD95/APO-1) receptor and its ligand play an important role in the initiation of apoptosis under many physiologic conditions. Loss of function mutations of the FAS gene have been described in lpr mice and in humans with autoimmune phenomena, recurrent lymphadenopathies, and hepatosplenomegaly. This syndrome is now called autoimmune lymphoproliferative syndrome type I (ALPS I). Recently, patients with similar clinical symptoms due to a functional FAS deficiency without FAS gene mutations have been distinguished. This disease has been termed autoimmune lymphoproliferative syndrome type II (ALPS II) or autoimmune lymphoproliferative disease (ALD). This report is the first description of the lymph node pathology and immunohistochemistry in a patient with ALPS II. After recurrent bacterial infections, a 4-year-old child developed cervical giant lymphadenopathy suggesting lymphoma. Lymph node histology resembled the findings in Epstein Barr virus-associated posttransplant atypical lymphoproliferations. Confluent sheets of immunoblasts, however, showed a monoclonal expression of IgG/lambda and a monoclonal rearrangement of the JH chain. The same clone was also present in the peripheral blood. Although high-grade lymphoma could not be excluded, the patient's parents insisted on the patient's leaving the hospital with only antibiotic treatment. Surprisingly, the giant lymphadenopathy completely resolved within 7 weeks, and the clone was no longer detectable in the peripheral blood. Twelve months later the patient was still free from lymphoma and was doing well. Retrospectively, transient monoclonal B-cell populations could be identified in an archival frozen blood sample taken when the patient was 3 years old. Increased FAS-independent spontaneous apoptosis was a feature of the patient's lymphocytes and could be the molecular basis for self-elimination of B-cell clones. We conclude that the diagnosis of a FAS-FAS-L deficiency should be considered in children with an otherwise unexplained atypical lymphoproliferation and that a diagnosis of lymphoma in patients with functional FAS deficiency should be made with considerable reservation.

Measles virus infection causes transient depletion of activated T cells from peripheral circulation.

BACKGROUND: Natural measles virus infection as well as vaccination with attenuated measles virus induce temporary immunosuppression, which is responsible for part of the morbidity and mortality associated with measles. The underlying molecular mechanisms are not known. Recently, in vitro studies have revealed a marked increase of LFA-1 expression of lymphocytes in the presence of infectious measles virus. OBJECTIVES: In order to further investigate immune dysfunction in measles we analyzed the expression of leukocyte function-associated antigen 1 (LFA-1) on ex vivo derived circulating human T cells. STUDY DESIGN: Expression of LFA-1 was measured by flow cytometry using monoclonal antibodies directed against CD11a and CD18. LFA-1 expression was followed in the course of infection in four adult seronegative vaccinees and in four patients with natural measles. RESULTS: There was a remarkable loss of LFA-1-bright cells during natural measles and after measles vaccination. The number of LFA-1-bright cells reached a minimum on day 7-14 after vaccination, and at the onset of rash during natural measles infection, and approached normal levels within 3-5 weeks. CONCLUSION: It is suggested that measles virus infection interferes with lymphocyte trafficking and reallocation. Disruption of recirculation and random homing of lymphocytes might contribute to the immunosuppression, which is characteristic for measles virus infection.

Compound-heterozygous mutations in the plasminogen gene predispose to the development of ligneous conjunctivitis.

Homozygous type I plasminogen deficiency has been identified as a cause of ligneous conjunctivitis. In this study, 5 additional patients with ligneous conjunctivitis are examined. Three unrelated patients (1 boy, 1 elderly woman, and 1 man) had plasminogen antigen levels of less than 0.4, less than 0.4, and 2.4 mg/dL, respectively, but had plasminogen functional residual activity of 17%, 18%, and 17%, respectively. These subjects were compound-heterozygotes for different missense mutations in the plasminogen gene: Lys19 --> Glu/Arg513 --> His, Lys19 --> Glu/Arg216 --> His, and Lys19 --> Glu/Leu128 --> Pro, respectively. The other 2 patients, a 14-year-old boy and his 19-year-old sister, who both presented with a severe course of the disease, exhibited plasminogen antigen and functional activity levels below the detection limit (<0.4 mg/dL and <5%, respectively). These subjects were compound-heterozygotes for a deletion mutation (del Lys212) and a splice site mutation in intron Q (Ex17 + 1del-g) in the plasminogen gene. These findings show that certain compound-heterozygous mutations in the plasminogen gene may be associated with ligneous conjunctivitis. Our findings also suggest that the severity of clinical symptoms of ligneous conjunctivitis and its associated complications may depend on the amount of plasminogen functional residual activity.

Human homozygous type I plasminogen deficiency and ligneous conjunctivitis.

On the basis of a questionnaire sent to the ophthalmology departments of hospitals throughout Germany, 10 patients with ligneous conjunctivitis or pseudomembranous disease, ranging in age from 1 to 71 years were identified. All 10 patients had severely reduced plasminogen levels. Genetic analysis revealed homozygous type I plasminogen deficiency (which had not previously been described in humans) in 7 patients and compound heterozygous plasminogen deficiency in 1 patient. Clear differentiation was not possible in 2 patients. Most of the parents had heterozygous plasminogen deficiency. None of the patients had experienced any episodes of thrombosis. Additionally, the following observations were made: 1) Levels of polymorphonuclear (PMN)-elastase protein were markedly elevated in 6 of 6 patients and 10 of 11 parents tested, and levels were higher in homozygotes than in heterozygotes. 2) Hereditary factor XII deficiency was found in 3 of 6 patients tested. 3) C1-inhibitor was elevated in 2 of 4 patients, prekallikrein was elevated in 1 of 4 patients, and plasminogen activator inhibitor type 1 was elevated in 1 of 4 patients. Infusions of lys-plasminogen concentrate induced pronounced fibrinolytic activity as indicated by high levels of D-dimer, increases in plasmin-antiplasmin complex and decreases in polymorphonuclear elastase. C1-inhibitor, prekallikrein and PAI-1 normalized after repeated infusions of lys-plasminogen. In contrast to dysplasminogenemia, severe type I plasminogen deficiency might be seen as a problem of extravascular space, in particular of the mucous membranes, possibly triggered by mechanically induced or inflammatory lesions of the vessels supplying the tissue.

Uncommon missense and splice mutations and resulting biochemical phenotypes in German patients with X-linked chronic granulomatous disease.

Chronic granulomatous disease is an inherited disease characterized by the inability of phagocytes to generate normal amounts of superoxide, leaving patients susceptible to opportunistic, life-threatening infections. In the majority of cases, cytochrome b558 is absent in the X-chromosomal form of CGD. However, the neutrophils from six of nine X-linked CGD patients, reported here, expressed normal or decreased amounts of this cytochrome and are referred to as "variant" forms. In three of these six variant patients, a roughly proportional decrease in cytochrome b558 expression and production of H2O2 were found. In two cases this phenotype could be well explained by special splice mutations, whereas in the third case it was caused by a missense mutation, predicting Ser 193-->Phe. In the other three variant patients, cytochrome b558 expression and H2O2 production were clearly disproportionate as the generation of H2O2 was much more decreased than cytochrome expression. Missense mutations also were found in these cases. One of these mutations, predicting Leu 546-->Pro and affecting the putative nicotinamide adenine dinucleotide phosphate binding site, led to normal levels of cytochrome b558 expression and reduced H2O2 production. In the other two mutations, predicting Pro 339-->His and His 338-->Tyr, the putative flavin adenine dinucleotide binding site was affected. This could explain the corresponding uncommon phenotypes, characterized by zero or trace amounts of H2O2 production and the expression of relatively high amounts of nonfunctional or low functional cytochrome b558, respectively. The only missense mutation found that prevented the expression of any cytochrome b558 was caused by a predicted His 222-->Arg exchange in one of the three classic cases. The two other classic phenotypes were caused by splice mutations.

Polymorphonuclear elastase in patients with homozygous type I plasminogen deficiency and ligneous conjunctivitis.

Laboratory studies were performed on six female patients (ranging in age from 1 to 31 years) with ligneous conjunctivitis, which we regard as a systemic condition consisting of ligneous conjunctivitis and other pseudomembranous lesions. Plasminogen levels were severely reduced in all six patients; five patients were homozygous, and one patient was double heterozygous for type I plasminogen deficiency. Of family members tested, 11 of 12 parents and two of six siblings tested were diagnosed as heterozygous. No thrombotic episodes had occurred in any of the patients. Polymorphonuclear (PMN) elastase protein levels were markedly elevated in all, significantly more so in the homozygous patients (range 88 to 335 ng/mL; normal range, 20+/-10 ng/mL) than in the heterozygous patient (58 ng/mL). Of 11 parents examined, only 1 mother had normal PMN elastase (27 ng/mL, with plasminogen antigen 60% and plasminogen functional activity 86%), whereas values were moderately elevated (range 42 to 110 ng/mL) in the other 10 parents examined. After plasminogen substitution, PMN elastase levels consistently decreased but did not reach normal values. We interpret our findings as indicating that non-plasmin-induced fibrinolytic processes, possibly mediated via elastase, may be intensified in patients with plasminogen deficiency.

Homozygous mutations in the plasminogen gene of two unrelated girls with ligneous conjunctivitis.

Ligneous conjunctivitis is a rare and unusual form of chronic pseudomembranous conjunctivitis that usually starts in early infancy. The disease may be associated with pseudomembranous lesions of other mucous membranes in the mouth, nasopharynx, trachea, and female genital tract. We examined two unrelated Turkish girls both suffering from ligneous conjunctivitis and occlusive hydrocephalus. Both children exhibited a severe plasminogen deficiency. Genomic DNA from both patients as well as from clinically healthy family members were screened for mutations in the plasminogen gene by polymerase chain reaction, single-strand conformation polymorphism (SSCP) analysis, and DNA sequencing. In the first girl with ligneous conjunctivitis a homozygous G-->A point mutation was identified in plasminogen exon 7 at position 780 leading to an amino acid exchange (Arg216-->His). Her healthy sister and her healthy parents were heterozygous for this mutation. The second patient revealed a homozygous G-->A point mutation in plasminogen exon 15 at position 1924 which leads to a stop-codon (Trp597-->Stop). The healthy parents were shown to be heterozygous for this mutation. In addition, the father's second allele revealed another mutation in the same codon (Trp597-->Cys) (compound heterozygosity). In conclusion, certain homozygous mutations in the plasminogen gene may cause ligneous conjunctivitis.

Homozygous type I plasminogen deficiency.

Homozygous type I plasminogen (Plg) deficiency has not been described in human subjects so far. Ligneous conjunctivitis is a rare and unusual form of chronic pseudomembranous conjunctivitis of unknown etiology. Here we report for the first time on homozygous type I Plg deficiency in three unrelated female patients who suffered from ligneous conjunctivitis and additional pseudomembranous lesions of other mucous membranes. The disease is caused by massive fibrin depositions within the "extravascular space" of mucous membranes because of absent clearance by plasmin. Infusions of albumin, fresh frozen plasma, or Lys-plasminogen (Lys-Plg) into two of the three patients revealed normal Plg activation capacity in these patients. The absence of fibrinolytic activity could therefore be shown to be due to Plg deficiency. Similar studies in the third patient have not been completed. In the two patients studied so far, infusions of Lys-Plg resulted in prompt and adequate Plg recovery with a short half-life and high amounts of plasmin-antiplasmin complexes and D-dimer. One patient additionally revealed an inherited partial factor XII deficiency. Functionally, this factor XII deficiency did not interfere with Plg activation. However, there may be a pathway of Plg activation in this patient via the prekallikrein C1-INH system.