[Sensitization by repeated skin tests with candidin and PHA].

Area of Science:

• Immunology
• Dermatology

Background:

• Intra-dermal skin tests (IST) are used to assess cell-mediated immunity.
• Understanding the impact of repeated skin testing is vital for accurate interpretation.

Purpose of the Study:

• To investigate the effect of repeated intra-dermal skin tests (IST) on immune responses.
• To determine if serial candidin and phytohemagglutinin (PHA) skin tests induce a booster effect.

Main Methods:

• 37 subjects received candidin IST, with a second test 10 days later.
• Mononuclear cells bearing Fc IgG receptors (RFc) were quantified in 17 subjects.
• 20 subjects received a second PHA IST 15 days after the first.

Main Results:

• Second candidin IST showed significantly greater induration diameters (p < 10⁻⁸) compared to the first.
• A strong correlation (r = 0.76, p < 0.001) existed between the first and second induration diameters.
• The absolute number of RFc cells increased significantly (p < 0.02) after the second candidin IST.
• Repeated PHA IST also resulted in increased induration diameters (p < 0.05).

Conclusions:

• Repeated intra-dermal skin tests with candidin and PHA induce a significant booster phenomenon.
• This heightened response may be attributed to an increase in T suppressor cells.
• The booster effect must be considered when interpreting serial IST results, particularly in immunodeficient individuals.