DAKIKI Cells

DAKIKI is a human Epstein-Barr virus (EBV)-positive B-lymphoblastoid cell line that expresses surface IgA1 and secretes polymeric IgA1. It was originally derived from peripheral lymphocytes of an adult patient with nasopharyngeal carcinoma and subsequently established as a continuously proliferating suspension culture. The cells exhibit typical lymphoblastoid morphology and grow in RPMI-based media supplemented with serum. DAKIKI has been widely used as a model of human IgA1-producing B cells, particularly for studies investigating immunoglobulin synthesis, regulation of secretion, and post-translational glycosylation.

Biochemical and lectin-based analyses have demonstrated that IgA1 secreted by DAKIKI cells displays galactose-deficient O-linked glycans within the hinge region. Monosaccharide compositional analysis and lectin ELISA confirm enrichment of terminal or α2,6-sialylated N-acetylgalactosamine (GalNAc) residues, a glycoform characteristic of aberrantly glycosylated IgA1 observed in IgA nephropathy. Neuraminidase treatment markedly increases Helix aspersa agglutinin reactivity, indicating the presence of sialylated GalNAc structures. Functional assays using Golgi-enriched fractions from DAKIKI cells demonstrate CMP-NeuAc:GalNAc-IgA1 α2,6-sialyltransferase activity, confirming the capacity of these cells to directly sialylate Gal-deficient O-glycans. Transcriptional analyses reveal expression of ST6-GalNAcII but not ST6-GalNAcI, supporting the role of ST6-GalNAcII in mediating α2,6 sialylation of hinge-region GalNAc in IgA1.

In addition to its utility in glycosylation research, DAKIKI has been evaluated for responsiveness to B-cell-inducing factors and phorbol esters, which can modulate immunoglobulin secretion in certain human B-cell lines. While DAKIKI constitutively secretes IgA, it has been included among EBV-transformed B-cell models used to study regulation of immunoglobulin production and differentiation states. Owing to its stable IgA1 secretion profile and reproducible production of galactose-deficient, α2,6-sialylated hinge-region glycans, DAKIKI represents a well-characterized in vitro system for investigating mechanisms of IgA1 glycosylation, B-cell differentiation, and the molecular pathogenesis of IgA-associated disorders.