[Inflammatory memory of pulmonary local lymphocytes in asthmatic mice].

Objective: To investigate if long-lived inflammatory memory exists in the airway of asthmatic mice, and whether pulmonary local lymphocytes could transfer the inflammatory memory.

Methods: 97 mice were divided into six groups by random number meter: asthma group (group A, n = 50), long term group (group B, n = 20), control group of long term (group C, n = 6), adoptive transfer group (group D, n = 12, subgroups D1, D2 and D3 divided based on the transferred cells counts), adoptive transfer control group (group E, n = 6), and naive group( group F, n = 3). There were subgroups using BSA (bovine serum album) substituting OVA (ovalbumin) for the second challenge, named subgroup B-BSA in group B and subgroup D-BSA in group D. Pathologic changes, alveolar eosinophil infiltration, total cell counts (TCC) in bronchoalveolar lavage fluid (BALF), leukocyte differentials, and BALF IL-5 level were assayed in every group. Comparisons of inflammation responses between group B and group A, also between group D and group A were made. From asthmatic mice 34 d post aerosol, bronchoalveolar lavage (BAL) cells and splenocytes free of red blood cells (NR-splenocyte in brief) were cultured in vitro and stimulated with allergens, to detect cell proliferations and IL-5 levels in the supernatant.

Results: (1) Vasculitis, alveolitis and bronchiolitis were observed in group A. TCC, BALF eosinophil and IL-5 reached peak on 240 h and 8 h, 24 h post aerosol respectively [ (22 +/- 5 ) x 10(4)/ml, (1.43 +/- 0.09) x 10(4)/ml and (75.1 +/- 52. 9) pg/ml, respectively]. There were scattered vasculitis and al)veolitis in group B before second OVA challenge; and more severe vasculitis and 3-fold higher alveolitis (ratio of alveolar eosinophil inflammation indexes is 21.23/7.14) were observed after second challenge. TCC and BALF eosinophils reached peak 24 h post aerosol [(121.5 +/- 19.1) x 10(4)/ml and (12.960 +/- 2.040) x 10(4)/ml respectively], BALF IL-5 reached to its highest level [(50.8 +/- 18.5) pg/ml] 48 h post aerosol. There were mild vasculitis in group B-BSA, while TCC [(5.3 +/- 2. 1) x 10(4)/ml] and eosinophil [(0.060 +/- 0. 050) x 10(4)/ml] were both significantly lower than those of group B 24 h post aerosol [(121.5 +/- 19. 1 ) x 10(4)/ml and (12.960 +/- 2.040) x 10(4)/ml respectively, P < 0.05]. BAL cells stimulated with OVA in vitro proliferated stronger [(166.8 +/- 4.81) Bq] than those with BSA stimulation [(61.0 +/- 24.1) Bq] (P < 0.05). Supernatant IL-5 levels in cell cultures with OVA or BSA stimulation were similar [(49 +/- 4) pg/ml and (46 +/- 21) pg/ml respectively] (P > 0.05). (2) There were vasculitis in group D2, with TCC [(5.0 +/- 1.0) x 10(4)/ml] and BALF IL-5 [(24.4 +/- 2.1) pg/ml] 24 h post aerosol. There were bronchiolitis in group D3, with TCC [(7.3 +/- 5.8) x 10(4)/ml] and BALF IL-5 [(45 +/- 6.2) pg/ml] 24 h post aerosol. There was significant difference between group D2 and D3 on BALF IL-5 (P < 0. 05), but not on TCC (P > 0. 05). No vasculitis was observed in group D-BSA, with TCC [(3.3 +/- 4.2) x 10(4)/ml] not statistically different from group D [(5.0 +/- 1.0) x 10(4)/ml] (P > 0. 05).

Conclusion: It is illustrated that long-lived inflammatory memory may exist in asthmatic mice lung, and pulmonary local lymphocytes may sufficient to transfer the memory.