Human leucocyte antigen class I and killer immunoglobulin‐like receptor expression patterns in T‐cell large granular lymphocyte leukaemia

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Abstract
T-cell large granular lymphocyte leukaemia (T-LGLL) is often associated with suppression of haematopoiesis through unknown mechanisms. Killer immunoglobulin-like receptors (KIRs) binding human-leucocyte antigen (HLA)-I in an allele-specific manner are frequently expressed by T-LGLL cells. HLA-I genotyping was performed in seven T-LGLL cases in which the neoplastic cells were known to express a single KIR isoform (CD158a, CD158b or CD158e). Five cases showed absence of the cognate HLA-I antigen for the expressed KIR isoform, resulting in KIR/HLA-I ‘mismatch’. Cytopenias occurred in all five ‘mismatch’ patients but not in two patients with ‘match’, suggesting that KIR/HLA-I mismatch may contribute to the suppression of haematopoiesis.