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The mechanisms of virus-induced airway hyperresponsiveness in asthma and allergy and the failure of host defence in patients suffering from secondary airway infections are still largely unknown. The aim of this study was to examine whether the presence of allergic rhinitis or susceptibility to recurrent sinusitis affects the structural and cellular changes in nasal mucosa during natural colds and convalescence. We compared the mucosal changes in biopsy samples during acute natural colds (days 2–4 of illness) and convalescence (3 weeks later) in patients with allergic rhinitis ( n = 9), patients with susceptibility to sinusitis ( n = 19) and healthy controls ( n = 20). We saw similarly increased numbers of mucosal T and B lymphocytes and mast cells and increased vascular density during the acute colds compared to convalescence in all the three groups. The allergic subjects had elevated levels of eosinophils in the acute phase ( P = 0·03), and the allergic and sinusitis-prone subjects had elevated levels of epithelial T cells ( P = 0·04) and low levels of mast cells ( P = 0·005) in convalescence compared to the control group. The sinusitis-prone subjects lacked intraepithelial cytotoxic cells in convalescence. In the allergic subjects, the reticular basement membrane was thicker in the acute phase compared to the convalescence ( P = 0·05). These results suggest that various cells of the airways, including inflammatory and structural cells, are involved during viral respiratory infections in subjects with allergic rhinitis. The small numbers of mast cells and cytotoxic lymphocytes in the sinusitis-prone subjects may be related to their susceptibility to bacterial complications. [ABSTRACT FROM AUTHOR]

SUMMARY Knowledge of the virus-induced immune response is important in understanding the pathophysiology of respiratory virus infections. Data on the cellular immune response is still limited and based mainly on experimental studies. Natural colds may differ in their pathophysiology from experimentally induced ones. To evaluate the inflammatory cell responses in the upper respiratory tract during natural colds we counted the number of lymphocytes, mast cells and macrophages in the nasal mucosa. Nasal biopsies were taken from 22 adult volunteers during the acute (2–4 days of symptoms) and convalescent phases (day 21) of the cold, and the numbers of cells were counted with immunohistochemical methods. Viral aetiology was identified in 14 (64%) subjects by using viral isolation, antigen detection and rhino-polymerase chain reaction assays. The number of T lymphocytes was increased in the nasal epithelium and that of T and B lymphocytes and mast cells in the subepithelial layer in the acute phase compared to the convalescent phase. Intraepithelial T lymphocyte counts were significantly higher in the subjects who had a proven viral infection or a finding of pathogenic bacteria in the nasopharynx compared to the subjects without such findings (P = 0·005 and P = 0·04, respectively). Contrary to the earlier experimental studies, we found that viruses cause accumulation of T and B lymphocytes and mast cells during the first days of a symptomatic naturally acquired respiratory infection. [ABSTRACT FROM AUTHOR]

Helicobacter pylori-induced in vitro stimulation of mononuclear cells was characterized by measuring DNA synthesis response, interferon-gamma (IFN-γ) secretion and the number of immunoglobulin- secreting cells. The strength of these responses was measured in 51 subjects comprising 36 dyspeptic patients from the Gastroenterological Unit and 15 members of the laboratory staff. Nineteen subjects had antibodies to H. pylori and 32 did not. The responses were compared with respect to H. pylori antibody status. Positive stimulation of DNA synthesis (stimulation index >2) was obtained in 96% of the subjects, and the bacterium induced IFN-γ secretion in all of them. The induction of immunoglobulin-secreting cells revealed B cell in vitro stimulation. The antibody-positive subjects had a tendency to synthesize less DNA (P not significant) and secrete less IFN-γ (P < 0.05) in response to H. pylori than did the antibody-negative ones, but the differences were not marked. The results show that the whole H. pylon bacterium stimulates mononuclear cells, The nature of the stimulation is not yet characterized (non-specific versus specific). [ABSTRACT FROM AUTHOR]