Lipoolygosaccharide indirectly enhances inflammatory lesions in lungs as aprimary infection site by non-encapsulated and type B Haemophilus influenzae through production of cytokines

We investigated the role of cytokines in differences in histopathologic cha nges in the lung between bronchopneumonia caused by non-encapsulated Haemop hilus influenzae strain 770235f(0)b(0) and systemic disease caused by type b H. influenzae strain 770235f(0)b(+). Tumour necrosis factor-alpha (TNF-al pha), interleukin-(IL)-6 and IL-1 beta levels in bronchoalveolar lavage flu id (BALF) samples of mice infected with strain 770235f(0)b(0) were higher t han in those infected with strain 770235f(0)b(0) until 24 h post-infection. Serum IL-6 rapidly increased in strain 770235f(0)b(0) infection after 72 h post-infection. Serum TNF-alpha level in strain 770235f(0)b(0) infection a ppeared earlier than in strain 770235f(0)b(0) infection. IL-1 beta producti on in strain 770235f(0)b(+) infection was later than in strain 770235f(0)b( 0) infection. Moreover, a biphasic concentration pattern of TNF-alpha and I L-6 was noted in BALF of mice with strain 770235f(0)b(0) infection. (C) 200 1 Academic Press.