Major histocompatibility complex class I polypeptide-related sequence A (MICA)

Major histocompatibility complex class I polypeptide-related sequence A (MICA) is a highly polymorphic, glycosylated cell surface protein encoded by the MICA gene within the MHC region on chromosome 6[1][2][7][10]. While structurally related to classical MHC class I molecules, MICA does not associate with β2-microglobulin nor present peptide antigens[1][2]. Its primary function is as a stress-induced ligand recognized by the NKG2D activating receptor on NK cells and various subsets of T cells, triggering cytotoxic responses against stressed, transformed, or infected cells[1][6]. MICA is strongly implicated as a target for immunotherapy in cancer and as a marker for immune activation in infection and transplantation settings[5]. Clinical antibodies targeting MICA are in development for oncology indications[5], and its expression and soluble isoforms are being evaluated as biomarkers for disease progression and therapeutic monitoring[2][4]. MICA exhibits substantial polymorphism affecting immune activation thresholds, with two main classes (type-I and type-II) defined by their NKG2D binding affinities due to specific linked amino acid variants[4]. If you need further organism-specific or variant-specific detail (e.g., MICA1 vs MICA2), or a more detailed account of clinical drugs, consult primary immunology databases or specific clinical trial records.

Other names

MHC class I polypeptide–related sequence AMIC-AMICA1MICA2PERB11.1

Antibody-mediated blocking of MICA–NKG2D interaction Cellular immunotherapy via enhanced recognition of MICA-expressing cells