Insights From a Single Case of Sporotrichosis: T Cell Receptor Repertoire Analysis Highlighting Antigen Specificity

Sporotrichosis is a subacute subcutaneous fungal infection caused primarily by Sporothrix globosa, typically following traumatic inoculation. The current diagnostic gold standard is fungal isolation and culture from the lesion, which requires significant time. The sporotrichin skin test, an intradermal reaction using crude polysaccharide antigens extracted from S. globosa, has been used in some countries as a relatively rapid diagnostic tool. While it demonstrates high sensitivity, evidence regarding its antigen specificity has not been sufficiently explored. Here, we report a T cell receptor repertoire analysis in a single case of sporotrichosis with a positive sporotrichin reaction. Skin tissue and peripheral blood samples were collected for the analysis, providing preliminary data that may guide future studies on the immunological basis of antigen-specific responses. TCR repertoire analysis revealed that in the α chain, the V1-2/J33 combination was dominantly expressed in both skin and blood, although the CDR3 sequences differed. In contrast, the β chain exhibited a diverse range of V and J gene combinations, with a notable increase in V11-2/J2-3 clonality in the skin sample compared to the blood. These findings suggest a potential antigen-specific response in the skin, although no Sporothrix-specific TCRs have been reported in public databases to date, as the relevant antigens remain unidentified. The data presented were obtained from a single case; however, they hold value as sporotrichin tests are no longer available in Japan. These findings offer a foundation for further investigations and may contribute to the development of improved diagnostic tools for sporotrichosis and other subcutaneous fungal infections.