Epitope of MHC class I mAb W6/32

John Ladasky ladasky at leland.Stanford.EDU
Wed Dec 4 20:26:17 EST 1996


In article <E1wBst.BMq at fsa.bris.ac.uk>,
S.D. Wainwright <ogsdw at ssa.bris.ac.uk> wrote:
>
>Can someone point me at refernces which describe
>the epitope of the human class I mAb W6/32
>
>Thanks in advance
>Shane Wainwright

	The W6/32 antibody reacts with all human class I molecules when
associated with beta-2 microglobulin.  W6/32 also reacts with class I
molecules from several other mammalian species.  The heavy-chain component
of the W6/32 epitope was mapped by comparing the sequences of various
reactive and non-reactive heavy chains.  The conclusion is that residue
121 of the heavy chain must be a lysine in order for W6/32 to bind.

	The association of the heavy chain with b2m is necessary but not
sufficient for the formation of the W6/32 epitope.  Even after many rounds
of immunoprecipitation with W6/32, other pan-HLA antibodies can pull down
lots of b2m-associated HLA-A, B, and C molecules.

	In a manner analogous to the heavy-chain sequence comparisons,
b2m sequences from various species have been compared in order to map the
b2m portion of the W6/32 epitope.  Now I hope you will excuse me while I
don my editorial hat and state that I think that the published b2m data
is incorrect.  Based on the sequences available in the late 1980's, re-
searchers concluded that residues 45 and 89 of the b2m molecule comprised
the b2m determinant of W6/32.  These residues are a long way from the 
residue in the heavy chain, over 25 angstroms as I recall.  The two resi-
dues aren't even that close to each other.  The argument has been advanced
that W6/32 recognizes a "large, discontinuous, conformational epitope" on
class I molecules.

	The problem, in my opinion, is that the sequences then available
had distracting, extraneous polymorphisms, and that there weren't enough 
sequences with the informative polymoprhisms.  In a few weeks, I hope to
submit a manuscript in which I derive a simpler picture from some new b2m
sequences.  I'm just waiting for one last transfectant to grow!

	Here's my list of references.  Good luck.

--------------------------------------------------------------------------

Barnstable, C. J., W. F. Bodmer, et al. (1978). *Production of Monoclonal
Antibodies to Group A Erythrocytes, HLA, and Other Human Cell Surface
Antigens - New Tools for Genetic Analysis.* Cell 14: 9-20.

Brodsky, F. M. and P. Parham (1982). *Evolution of HLA Antigenic
Determinants: Species Cross-reactions of Monoclonal Antibodies.*
Immunogenetics 15: 151-166.

Crepaldi, T., S. D'Alfonso, et al. (1991). *Activated human T cells express
b2-microglobulin-associated HLA-A,B,C molecules not recognized by W6/32 mAb.
Tissue Antigens 37: 138-140.
	
Jefferies, W. A. and G. G. MacPherson (1987). *Expression of the W6/32 HLA
epitope by cells of rat, mouse, human and other species: critical dependence
on the interaction of specific MHC heavy chains with human or bovine b2-
microglobulin.* Eur. J. Immunol. 17: 1257-1263.
	
Kahn-Perles, B., C. Boyer, et al. (1987). *Acquisition of HLA Class I W6/32
Defined Antigenic Determinant by Heavy Chains from Different Species
Following Association with Bovine b2-microglobulin.* J. Immunology 138(7):
2190-2196.
	
Maziarz, R. T., J. Fraser, et al. (1986). *The human HLA-specific monoclonal
antibody W6/32 recognizes a discontinuous epitope within the alpha 2 domain
of murine H-2Db.* Immunogenetics 24(3): 206-208.
	
Parham, P. and H. L. Ploegh (1980). *Molecular Characterization of HLA-A,B
Homologues in Owl Monkeys and Other Nonhuman Primates.* Immunogenetics 11:
131-143.

Parham, P., P. K. Sehgal, et al. (1979). *Anti HLA-A,B,C monoclonal
antibodies with no alloantigenic specificity in humans define polymorphisms
in other species.* Nature 379: 639-641.

-- 
Unique ID : Ladasky, John Joseph Jr.
Title     : BA Biochemistry, U.C. Berkeley, 1989  (Ph.D. perhaps 1998???)
Location  : Stanford University, Dept. of Structural Biology, Fairchild D-105
Keywords  : immunology, music, running, Green



More information about the Immuno mailing list