Rationale: β-D-Glucans are fungal cell wall polysaccharides that stimulate innate immune responses and are responsible for bioaerosol-induced respiratory symptoms in both indoor and occupational environments.

Methods: C3HeB/FeJ mice were exposed to pustulan (1®6)-β-D-linear glucan in the scheme shown in the Table below. At days 0 and 7 mice were injected intraperitoneally (i.p.) with bovine serum albumin conjugates (pustulan-BSA) with an adjuvant (25μg/ml of pustulan emulsified with 1mg/ml of alum in saline) or saline with/without alum. Negative control mice were injected with saline or alum. At days 14-16, 21-23, and 28-30 mice were challenged intranasally (i.n.) with pustulan (25 μg/mouse in 50μl). Control mice received saline.  Inflammation induced by pustulan was evaluated at day 31 by lung histology and evaluation of bronchoalveolar lavage fluid (BALF).

Results: Lung histology showed the highest degree of inflammation in mice pretreated with pustulan-BSA conjugate and i.n.-exposed to pustulan. Total BALF cells and cell types, are summarized below. Alum injection followed by pustulan or saline instillation produced an influx of monocytic cells to the lung. Pustulan instillation following saline injection also induced recruitment of monocytes. Significant neutrophilic influx was seen in all mice exposed to i.n. pustulan.

Conclusion: Pre-exposure to pustulan-protein conjugate is necessary for induction of neutrophilic inflammation upon inhalation of pustulan in mice.