VMC 221: Veterinary Immunology and Serology (1+1)

HYPERSENSITIVITY PNEUMONITIS

• Type III hypersensitivity reactions may occur in lungs when sensitized animals inhale antigens.
• Example: Cattle fed moldy hay ( when hay is stored in damp, thermophilic actinomycetes will grow) for long periods, can become sensitized to spores of Saccharopolyspora rectivirgula ( Micropolyspora faeni) .
• Eventually, when spores are inhaled, antibodies formed against spore antigen will form immune complexes resulting in complement activation and interstitial pneumonia.
• A hypersensitivity pneumonitis seen in farmer’s chronically exposed to S. rectivirgula spores is called farmer’s lung (Hay sickness is a condition seen in horses which is similar to farmer’s lung).
• A similar condition arising from exposure to dust from pigeon faeces is called as pigeon breeder’s lung.
• Other conditions are mushroom grower’s lung, librarian’s lung etc.