Skin tests with influenza virus.

Area of Science:

• Immunology
• Virology
• Dermatology

Background:

• Influenza viruses are a significant cause of respiratory illness.
• The immune response to influenza infection involves both humoral and cellular immunity.
• Understanding delayed hypersensitivity in viral infections is crucial for vaccine development.

Purpose of the Study:

• To investigate skin reactions induced by influenza A and B viruses.
• To determine the relationship between skin test results and circulating antibodies.
• To assess the protective effect of skin test positivity against influenza A (H3N2) challenge.

Main Methods:

• Purified influenza A and B viruses were injected into normal subjects.
• Skin reactions were monitored for timing and histological characteristics.
• Subjects underwent intranasal challenge with attenuated influenza A (H3N2).

Main Results:

• Skin reactions peaked at 24-48 hours and showed histological features of delayed hypersensitivity.
• No strong correlation was found between skin test results and antibody levels.
• None of the 13 skin-test-positive subjects were infected after influenza A (H3N2) challenge, compared to 5 of 14 skin-test-negative subjects.

Conclusions:

• Influenza virus can elicit a delayed hypersensitivity skin reaction in normal individuals.
• Skin test positivity to influenza viruses may indicate a degree of protection against infection.
• Cellular immunity, as indicated by skin tests, might play a role in influenza protection beyond antibody presence.