The effect of soluble material from mouldy hay dust on the complement system

Area of Science:

• Immunology
• Biochemistry
• Pulmonary Medicine

Background:

• Mouldy hay dust exposure is linked to respiratory conditions like farmer's lung.
• The mechanisms behind non-immune histamine release and lung inflammation from inhaled dusts are not fully understood.

Purpose of the Study:

• To investigate the anti-complementary and enzymatic activities of soluble components from mouldy hay dust.
• To elucidate the role of these components in complement activation and potential links to lung diseases.

Main Methods:

• Fractionation of soluble mouldy hay dust material by molecular weight.
• Assays to determine anti-complementary activity (C1 activation, C3-9 depletion) and enzyme function (IgG cleavage).
• Comparison of activity between soluble and particulate dust fractions.

Main Results:

• A high molecular weight fraction (approx. 800,000) directly activated complement C1.
• A lower molecular weight enzyme (approx. 30,000-38,000) cleaved IgG into Fab and Fc-like components.
• Soluble dust material showed significantly higher C3-9 activation (up to 66x) compared to particulate material.
• The enzyme exhibited papain-like activity.

Conclusions:

• Soluble mouldy hay dust components possess potent anti-complementary and papain-like enzymatic activities.
• C1 activation by dust components may mediate non-immune histamine release in the lungs.
• The papain-like enzyme activity could be relevant to the pathogenesis of emphysema observed in farmer's lung.