House-dust-mite allergen (Der p 1) levels in university colleges

Background In coastal Australia, mean house-dust-mite allergen concentration is 20-40 times higher in homes than in public buildings. Allergen concentrations in university colleges, which share some eharacteristics of both homes and public buildings, are not known. The study aimed to compare bed mite-allergen concentration in colleges with local homes.
Methods Mattress dust was collected from three colleges (n = 60 m each) and local homes (N=68) during summer, Der p 1 was measured by ELISA. Information was collected on the floor plan of the colleges, cleaning practices, age of building, and orientation of room.
Results Most college mattresses (94%) had Der p 1 concentrations less than the mean of homes in the same climate. The geometric means of Der p 1 m the mattresses of the colleges were as follows: A, 8.9 pg Der p 1/g fme dust (95% CI 6.9,11.5); B, 1.9 (1.5,2.3); and C, 1.5 (1.2,2.0), compared to homes, 22,5 (17.6, 28.7). The percentages of college mattresses with less than 2 jig/ g were 7%, 48%, and 58%, respectively, compared to 4% for homes. Higher Der p 1 concentrations were weakly associated with age of building in college A, and orientation in college B, Der p 1 concentrations were independent of floor level and age of mattress.
Conclusions These findings indicate that low allergen concentrations are achievable without extreme hygiene and cleaning measures in a climate which supports mite proliferation in homes.     

Postinflammatory ossicular fixation: CT analysis with surgical correlation

Postinflammatory ossicular fixation is a common problem encountered by the otologic surgeon upon exploration because of conductive hearing loss in patients with chronic otitis media. These nonotosclerotic noncongenital lesions take three pathologic forms: fibrous tissue fixation (chronic adhesive otitis media), hyalinization of collagen (tympanosclerosis), and new bone formation (fibro-osseous sclerosis). Fibrous tissue fixation appears on CT as nonbony, noncalcific soft-tissue debris encasing some or all of the ossicular chain. Tympanosclerosis appears as unifocal or multifocal punctate or weblike calcifications in the middle ear cavity or on the tympanic membrane. This debris may be in direct apposition to the ossicular chain or may replace the suspensory ligaments in symptomatic patients. New bone formation has been identified only in the attic and is the least common manifestation. Thick bony webs or generalized bony encasement may be present at CT. More than 300 patients with the clinical diagnosis of chronic otitis media have been examined. This study encompasses 23 proved cases.     

Mite allergen content in commercial extracts and in bed dust determined by radioallergosorbent tests.

Radioallergosorbent (RAST) direct binding and inhibition type assays were used to quantitate the mite (Dermatophagoides pteronyssinus) allergen content of four commercial mite extracts and a laboratory prepared extract from freeze-dried mites. The content of mite allergen in extracts prepared from twenty samples of dust vacuumed from bedding was measured by RAST inhibition assay. The four commercial mite extracts designated A, B, C and D, and the laboratory extract, designated L, contained 52, 265, 108, 1.5 and 581 arbitrary units of allergen/ml for the direct binding assay and 128, 111, 217, approximately 1 and 1083 arbitrary, but different, units of allergen/ml for the inhibition assay respectively. Qualitative differences between at least two extracts were suggested by the different slopes obtained when allergen binding of anti IgE was plotted against the volume of extract used in the direct binding assay. Differences in slope between the two extracts were also apparent when they were used in the inhibition assay. The quantities of mite allergen/gm of bed dust expressed in arbitrary units for the inhibition assay were 24 to 457 (mean 129) units. These quantities are similar to and sometimes greater than the quantity in 1 ml of mite extract and so confirm bed dust as a potent source of mite allergen. There was no significant correlation between the weight of dust, the numbers of dead and live mites and the allergen content of dust.     

Relationship of B cell Fc receptors to T cell recognition of Mls antigen

The Mls locus on chromosome 1 controls the expression of cellular determinants that are responsible for stimulating mixed lymphocyte reactions between H-2-identical strains. However, the biochemical nature of Mls antigenic determinants remains undefined. It has been proposed that Ly-17 lymphoid cell surface antigens (also known as Ly.m.20.2 and LyM-1) and Mls antigens could be identical because they are both encoded by loci on chromosome 1 and display similar tissue distribution. The Ly-17 locus encodes polymorphic alleles of the IgG Fc receptor (Fc gamma R). In the present study, two approaches were used to address the question of whether Fc gamma R are involved in T cell recognition of Mls antigen. In the first approach we tested the effect of Fc gamma R blockade by heat-aggregated mouse IgG or anti-Fc gamma R monoclonal antibodies (2.4.G2) on the ability of an Ia+, Fc gamma R+ Mlsa-expressing B cell hybrid (LBB.3.4.16) to stimulate interleukin 2 secretion by an anti-Mlsa-specific T cell hybrid. We show that blockade of Fc gamma R does not inhibit the Mlsa-specific stimulation of T cells during a 24-h culture period in which Fc gamma R remain blocked. In the second approach, we derived irradiation-induced variants of LBB.3.4.16 to dissociate Fc gamma R expression and Mls antigen expression. We describe 2 LBB variants which no longer stimulate Mlsa-reactive T cells but do express Fc gamma R. Compared to parental LBB cells, the capacity of variant LBB cells to present soluble antigen to Ia-restricted T cells is unaffected. Collectively, these results indicate that Fc gamma R expression and Mlsa antigen stimulation can be dissociated. We conclude that Fc gamma R expression may be necessary, but not sufficient for T cell recognition of Mls antigen.     

Pilot Study for Large-Scale Plasma Procurement Using Automated Plasmapheresis

A pilot study for large-scale automated plasmapheresis using the Haemonetics Model 50 machine was undertaken in the Yorkshire Region of the United Kingdom to determine the viability of such a programme for national self-sufficiency in fresh plasma procurement for factor VIII concentrate production. The study was designed to resolve three areas of concern: donor safety and recruitment; a cost analysis, and the choice of anticoagulant for optimum factor VIII yields. The results show that large-scale automated plasmapheresis could safely and economically produce high-quality source plasma necessary for national self-sufficiency.     

Injection of mice with antibody to interferon enhances the growth of transplantable murine tumors

Injection of DBA/2, C57Bl/6, or BALB/c mice with antibody to mouse interferon alpha/beta enhanced the i.p. transplantability of six different murine tumors, as manifested by an increase in the percentage of tumor-bearing mice and a decrease in survival time. The effect was observed in mice injected with antibody to interferon raised in three sheep, a goat, and a rabbit, but not with sheep antibody to "impurities" present in the mouse interferon preparations or with normal sheep or goat globulins. The enhancement in transplantability was most marked when tumor cells had been previously passaged in vitro and were of low tumorigenicity. Analysis of some of the experimental conditions using interferon-sensitive and interferon-resistant lines of Friend erythroleukemia cells (FLC) showed that the enhancing effect was observed over a wide range of tumor cell inocula, was directly related to the amount of antibody to interferon injected and was most pronounced when antibody was administered at the time of tumor cell injection. Enhancement was also observed when FLC were injected subcutaneously (s.c.). Antibody did not act directly on the tumor cells in vitro. Although we were unable to demonstrate any biologically active interferon in mice before or after tumor cell inoculation, the results suggest that endogenous interferon is present and plays a role in inhibiting the transplantability of some murine tumors in immunocompetent mice.