Hyperexpressed hairy leukemic cell Ii might bind to the antigen-presenting site of class II MHC molecules
Graduate School of Biomedical Sciences; Department of Pharmacology; Department of Pediatrics; Department of Cell Biology
Medical Subject Headings
*Antigens, Differentiation, B-Lymphocyte; Cell Line, Transformed; Cell Transformation, Viral; Herpesvirus 4, Human; *Histocompatibility Antigens Class II; Humans; Leukemia, Hairy Cell; Membrane Proteins; Molecular Weight; Sialoglycoproteins; Tumor Cells, Cultured
Life Sciences | Medicine and Health Sciences
The p35 protein which is hyperexpressed on hairy leukemic cells was determined to be Ii, the electrophoretically invariant glycoprotein that is associated with class II major histocompatibility complex (Ia) antigens from the time of their synthesis. The principal function of class II MHC antigens is to present to T cell receptors those digested foreign antigenic peptides that probably fold as amphipathic alpha-helices and adsorb to a hydrophobic surface (desetope) on Ia. By a novel strip-of-helix hydrophobicity algorithm we found that the sequence Leu-142 to His-170 in Ii formed a five-cycle, amphipathic, alpha-helix, the highest scoring one among a series of proteins commonly used as experimental antigens. This finding led to the hypothesis that this sequence in Ii bound to the antigen-binding site (desetope) of Ia until release and self-aggregation in the endosome in order that digested foreign peptides could then bind to Ia. Abundant expression of Ii in leukemic cells might be associated with an altered capacity of those cells to present foreign or leukemic antigens to the host's immune system.
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Citation: Leukemia. 1987 Apr;1(4):395-6.
Leukemia : official journal of the Leukemia Society of America, Leukemia Research Fund, U.K
Elliot, William L.; Lu, Shan; Nguyen, Que; Reisert, Patricia S.; Sairenji, Takeshi; Sorli, Christopher H.; Stille, Christopher J.; Thomas, Lawrence James; and Humphreys, Robert E., "Hyperexpressed hairy leukemic cell Ii might bind to the antigen-presenting site of class II MHC molecules" (1987). GSBS Student Publications. 340.