Cell surface sialic acid influences tumor cell recognition in the mixed lymphocyte reaction

L. D. Powell, S. W. Whiteheart, G. W. Hart

Research output: Contribution to journalArticlepeer-review

63 Scopus citations

Abstract

The Ia+ B cell lymphoma, AKTB-1 b, fails to stimulate thymic lymphocytes in a one-way mixed lymphocyte reaction unless pretreated with sialidase or inhibitors of N-linked oligosaccharide processing. A comparison of different sialidases and sialyltransferases suggests that the removal of only a subset of total surface sialic acid rather than net desialylation of the cell surface, is required. Three sialidases were compared, including Vibrio cholerae (VC) and Clostridium perfringens (CP), which will cleave α2-3, α2-6, and α2-8, sialic acid linkages, and Newcastle Disease virus (NDV), which will remove only α2-3 and α2-8 linked sialic acid. When treated with equivalent units of sialidase, CP-, VC-, and NDV-treated cells were 24-fold, sixfold, and threefold better stimulators than untreated cells. In contrast, VC released 1.3-fold and 2.5-fold more sialic acid per cell than did CP or NDV, respectively. Furthermore, VC was superior in reducing the levels of binding of the sialic acid-specific lectin, Limulus polyphemus agglutinin, in exposing Galβ1-3GalNAc and Galβ1-4GlcNAc residues, and in desialylating gangliosides. Two-dimensional gel analysis indicated that VC and CP were both equal and superior to NDV in the desialylation of iodinatable cell-surface proteins, including H-2K(k), I-Aβ(k), and a highly sialylated 65,000 dalton protein of unknown identity. Maximal resialylation of CP-treated cells with exogenously added CMP-NANA and either the α2-3(Galβ1-3GalNAc) or α2-6(Galβ1-4GlcNAc) sialyltransferase did not reduce the stimulatory capacity of these cells. However, resialylation of VC-treated cells with just CMP-NANA alone resulted in 49% reversal of their stimulatory capacity, and no additional reversal could be achieved with either of the sialyltransferases. Although the α2-6(Galβ1-4GlcNAc) sialyltransferase was capable of adding back approximately 10% of the sialic acid removed, the endogenous activity added back approximately 0.1% of the total sialic acid removed. SDS-PAGE gels of the sialylated cells indicated that the exogenously added sialyltransferase labeled many different proteins, whereas the endogenous activity labeled far fewer proteins, predominantly in 46,000 and 25,000 m.w. range. Both the desialylation and resialylation data suggest that the sialidase-dependent stimulation is due to the desialylation of specific membrane structures. Together with previous studies, these data suggest that the sialic acids involved are probably α2-6 linked to N-linked glycosyl moieties.

Original languageEnglish
Pages (from-to)262-270
Number of pages9
JournalJournal of Immunology
Volume139
Issue number1
StatePublished - 1987

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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