Abstract:
:Class Ib Qa-2 molecules are expressed in tissue culture cells as approximately 40-kDa membrane-bound, glycophosphatidylinositol-linked antigens and as approximately 39-kDa soluble polypeptides. Recently, alternative splicing events which delete exon 5 from a portion of Qa-2 transcripts were demonstrated to give rise to truncated secreted Qa-2 molecules in transfected cell lines. To determine whether this mechanism operates in vivo and to find out whether Qa-2 can be detected in soluble form in circulation, murine blood samples were analyzed. Critical to these experiments was preparation of an anti-peptide antiserum against an epitope encoded by a junction of exon 4 and exon 6. We find that supernatants of splenocytes cultured in vitro as well as serum or plasma contain two forms of soluble Qa-2 molecules. One form corresponds to a secreted molecule translated from transcripts from which exon 5 has been deleted; the other is derived from membrane-bound antigens or their precursors. The levels of both soluble forms of Qa-2 are inducible upon stimulation of the immune system, suggesting an immunoregulatory role for these molecules or for the mechanism leading to the reduction of cell-associated Qa-2 antigens in vivo.
journal_name
Proc Natl Acad Sci U S Aauthors
Tabaczewski P,Shirwan H,Lewis K,Stroynowski Idoi
10.1073/pnas.91.5.1883subject
Has Abstractpub_date
1994-03-01 00:00:00pages
1883-7issue
5eissn
0027-8424issn
1091-6490journal_volume
91pub_type
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