Used in immunological research to quantify CD40 protein levels in biological samples such as serum, plasma, and cell culture supernatants. Enables study of immune cell activation, particularly in dendritic cells, B cells, and macrophages. Supports research in autoimmune diseases, cancer immunotherapy, and inflammatory conditions by measuring CD40 expression as a marker of immune response. Facilitates evaluation of therapeutic agents targeting the CD40-CD40L pathway. Suitable for high-throughput screening and mechanistic studies in preclinical models.