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

We investigated the role of cytokines in differences in histopathologic changes in the lung between bronchopneumonia caused by non-encapsulated Haemophilus influenzae strain 770235f(0)b(0)and systemic disease caused by type b H. influenzae strain 770235f(0)b(+). Tumour necrosis factor-alpha (TNF-alpha), interleukin-(IL)-6 and IL-1 beta levels in bronchoalveolar lavage fluid (BALF) samples of mice infected with strain 770235f(0)b(0)were higher than in those infected with strain 770235f(0)b(+)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 appeared earlier than in strain 770235f(0)b(+)infection. IL-1 beta production 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 IL-6 was noted in BALF of mice with strain 770235f(0)b(0)infection. Copyright 2001 Academic Press.