In both patients and experimental animals, immunoglobulin G (IgG) has been found to dominate acute otitis media with effusion (OME), whereas IgA tends to be present in chronic but not in acute OME. To determine whether local immunoregulation could account for this difference, the expression of cytokines associated with the production of different antibody isotypes was investigated in experimental acute and chronic OME. Mice were systemically immunized and then challenged transtympanically, once to produce an acute OME or once per week for 6 weeks to produce chronic OME. Hybridization with molecular probes for cytokine genes showed that cells producing interleukin-2 (IL-2) and IL-4, but not IL-5, were present during acute OME. In chronic OME, IL-2-positive (IL-2+) and IL-4+ cells were less prevalent, but IL-5+ cells were numerous. These finding support a model by which locally produced IL-2 and IL-4 augment IgG production in acute OME, whereas, IL-5 contributes to increased IgA production in chronic OME.

Vestibular schwannoma (VS) may present clinically in one of two forms: sporadic unilateral or hereditary bilateral. Almost all cases of familial transmission have been associated with the diagnosis of neurofibromatosis type II (NF-2). In this report, we describe nine families (18 individuals) presenting with unilateral VS without evidence of NF-2. In four of the nine families, the affected individuals were of parent-offspring relationship, in three families they were cousin-cousin, and in the remaining two families, they were sibling-sibling and aunt-nephew. No other members of the families were diagnosed with NF-2. There was no evidence for gender predilection or genomic imprinting among affected individuals. This study suggests that familial occurrence of unilateral VS may be genetically inherited as it occurs more commonly than would be estimated by chance alone. Future genetic studies will elucidate whether occurrence of unilateral VS in these families represents a variable expression of NF-2, chance occurrence of unilateral VS in families, or a new genetic disorder.

Hypothesis: Similar to familial tumors, sporadic head and neck paragangliomas are associated with chromosomal deletions at either 11q13 or 11q22-23. Background: Familial paragangliomas are inherited in an autosomal dominant pattern with genomic imprinting of the maternal allele. Genetic studies of familial paragangliomas have localized the causative genetic defect to two separate loci: 11q13.1 and 11q22-23. The molecular pathogenesis of sporadic head and neck paragangliomas has not been studied. Methods: Blood and tumor samples from patients with sporadic head and neck paragangliomas were screened for deletions on chromosome 11 using DNA microsatellite markers and polymerase chain reaction. Polymerase chain reaction-amplified alleles from tumor specimens were compared with those from the blood of eight patients. A greater than 50% reduction in band intensity (as determined by densitometric analysis) between blood and tumor sample was indicative of a chromosomal deletion. Results: Three of the eight patients were found to have deletions at chromosome 11q: two at chromosome 11q22-23 and one at 11q13. Conclusions: Sporadic head and neck paragangliomas are associated with deletions at chromosome 11q13 and 11q22-23. It is thus likely that sporadic and familial paragangliomas share a similar molecular pathogenesis.

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Vestibular schwannoma may present clinically in two forms: sporadic unilateral or hereditary bilateral. Familial transmission of vestibular schwannoma is known to occur only in neurofibromatosis type II (NF-2). We have previously described the clinical characteristics of unilateral vestibular schwannoma presenting in families, in the absence of ther criteria necessary for the diagnosis of NF-2. Polymerase chain reaction-single strand chain polymorphism was used to screen for germline NF-2 gene mutations in six families with unilateral vestibular schwannoma. Direct sequencing of DNA from blood was done in affected subjects from three families. No germline mutations were identified. Because NF-2 gene mutations are detected in only 33% of patients with NF-2, hereditary transmission of mutations cannot be entirely excluded. However, in the absence of germline mutations in the NF-2 gene, familial occurrence of unilateral vestibular schwannoma more likely represents either a chance somatic NF-2 gene mutation or originates from a separate genetic loci.