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Histoplasmin-CYL, a yeast phase reagent in skin test studies with humans
Abstract:
A yeast phase histoplasmin, designated CYL, was studied in 156 humans living in areas of the United States endemic for histoplasmosis, coccidioidomycosis, or both fungal entities. Comparisons were made with Food and Drug Administration reference mycelial histoplasmin. Among persons without concurrent spherulin sensitivity, reactor rates and sizes were the same with both reagents. Some persons with spherulin sensitivity reacted only to the mycelial reagent. Histoplasmin-CYL skin tests did not induce significant changes in complement-fixing antibody in histoplasmin-reactive subjects.
Insights
A new yeast phase histoplasmin (CYL) showed comparable skin test results to the standard mycelial reagent in endemic populations. However, some individuals with spherulin sensitivity reacted exclusively to the mycelial form.
Area of Science:
- Mycology
- Immunology
- Infectious Diseases
Background:
- Histoplasmosis and coccidioidomycosis are endemic fungal infections in the United States.
- Skin testing is a common method for assessing sensitivity to fungal antigens.
- A yeast phase histoplasmin (CYL) was developed for potential diagnostic use.
Purpose of the Study:
- To evaluate the performance of a yeast phase histoplasmin (CYL) in comparison to a standard mycelial histoplasmin.
- To assess the reactivity of CYL skin tests in individuals from histoplasmosis-endemic areas.
- To determine if CYL skin tests induce changes in complement-fixing antibodies.
Main Methods:
- A yeast phase histoplasmin (CYL) was administered as a skin test to 156 humans in endemic areas.
- Reactions were compared to those from a Food and Drug Administration reference mycelial histoplasmin.
- Complement-fixing antibody levels were monitored post-skin testing in reactive subjects.
Main Results:
- Histoplasmin-CYL skin tests showed similar reactor rates and sizes to the mycelial reagent in individuals without concurrent spherulin sensitivity.
- A subset of individuals with spherulin sensitivity reacted only to the mycelial histoplasmin, not to CYL.
- Histoplasmin-CYL skin tests did not cause significant alterations in complement-fixing antibody titers.
Conclusions:
- The yeast phase histoplasmin (CYL) demonstrates comparable efficacy to the standard mycelial histoplasmin for skin testing in endemic populations.
- CYL may offer a distinct reactivity profile in individuals with co-existing spherulin sensitivity.
- Histoplasmin-CYL skin testing appears safe, with no significant impact on antibody levels.