ovalbumin and Remission--Spontaneous

Asthma is associated with recruitment of eosinophils, accumulation of chronic inflammatory cells in the airway walls, subepithelial fibrosis and other structural changes of airway wall remodelling. The role of ongoing exposure to allergens in their pathogenesis remains unclear.. To examine whether changes of inflammation and remodelling were reversible following cessation of antigenic challenge in a mouse model of chronic asthma.. BALB/c mice sensitized to ovalbumin (OVA) were chronically challenged by inhalation of a low mass concentration of antigen for 8 weeks, leading to development of acute-on-chronic airway inflammation, subepithelial fibrosis and other changes of airway wall remodelling. Epithelial injury was assessed by immunohistochemistry, while inflammation and remodelling were quantified by appropriate histomorphometric techniques. Regression of lesions was assessed in animals examined at 1, 2 and 4 weeks after exposure to OVA ceased.. We did not find evidence of airway epithelial injury in this model of low-level chronic inhalational exposure to antigen. Persistence of the recruitment of eosinophils and chronic inflammatory cells in the airway walls was dependent on continuing antigenic challenge, as was persistence of mucous cell hyperplasia/metaplasia. Subepithelial fibrosis and epithelial hypertrophy exhibited delayed reversibility following cessation of exposure to antigen, possibly related to matrix-associated accumulation of transforming growth factor-beta(1).. In chronic asthma, low-level antigenic challenge may be required to maintain the inflammatory response in the airway wall, but airway remodelling may persist in its absence.

Topics: Administration, Inhalation; Allergens; Animals; Asthma; Chronic Disease; Disease Models, Animal; Eosinophils; Epithelial Cells; Female; Fibrosis; Hyperplasia; Mice; Mice, Inbred BALB C; Ovalbumin; Remission, Spontaneous; Respiratory Mucosa; Trachea; Transforming Growth Factor beta; Transforming Growth Factor beta1

Experimental autoimmune encephalomyelitis (EAE) was induced in Lewis rats by the i.v. injection of 10(7) cloned V beta 8.2+ T cells specific for the 72-89 peptide of guinea pig myelin basic protein (MBP). Some animals were injected simultaneously with 10(7) cloned T cells specific for ovalbumin (OVA). Lymphocytes were isolated from the spinal cord and from the peripheral lymphoid organs of these rats and the frequencies of MBP-peptide-specific or OVA-specific proliferating cells were estimated by limiting dilution analysis at different times after cell transfer. The frequencies of cells specific for MBP72-89 or OVA in the spinal cord were highest 5 days after cell transfer (MBP72-89, 1 in 1149; OVA, 1 in 1116). On day 7, when the rats were recovering, the frequency of cells specific for MBP72-89 in the spinal cord fell dramatically to < 1 in 10(5), while that of OVA-specific cells decreased to a much lesser extent (1 in 7001). The frequencies of MBP72-89-specific cells in the peripheral lymphoid organs during and after recovery were also much lower than those of OVA-specific cells. A similar pattern of down-regulation of the MBP-peptide-specific, but not the OVA-specific, T cell response was observed in the spleen and mesenteric lymph nodes (MLN) of rats 38 days after the active induction of EAE by immunization with equal amounts of MBP and OVA in adjuvants. In the passively transferred model, cells isolated from the spinal cord and MLN on day 7 did not regain responsiveness to MBP72-89 after incubation with high levels of IL-2, indicating that the unresponsiveness was not due to T cell anergy. Thus this study demonstrates that there is a specific down-regulation of the MBP72-89-specific T cell response during spontaneous recovery from EAE.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Apoptosis; Clonal Deletion; Down-Regulation; Encephalomyelitis, Autoimmune, Experimental; Female; Immunization, Passive; Interleukin-2; Lymph Nodes; Lymphocyte Count; Male; Mesentery; Myelin Basic Protein; Ovalbumin; Rats; Rats, Inbred Lew; Remission, Spontaneous; Spinal Cord; Spleen; T-Lymphocytes

Topics: Adjuvants, Immunologic; Albumins; Animals; Antibodies; Antibody Formation; Azathioprine; Immunodiffusion; Immunotherapy; Isoenzymes; L-Lactate Dehydrogenase; Leukemia L1210; Mice; Mice, Inbred DBA; Ovalbumin; Remission, Spontaneous; Swine