One or multiple immunoglobulins capable of binding to specific antigenic determinants and intended to be used for the qualitative and/or quantitative detection of T-cell immunoreceptor with Ig and ITIM domains (TIGIT), also known as v-set and immunoglobulin domain-containing protein 9 (VSIG9) and v-set and transmembrane domain-containing protein 3 (VSTM3), in a clinical specimen.