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Infect. Immun., Oct 1997, 4190-4198, Vol 65, No. 10
BC Cole, AD Sawitzke, EA Ahmed, CL Atkin and CS David
Mycoplasma arthritidis, an agent of rodent arthritis, produces a potent
superantigen (SAg), MAM. Previous work established that MAM is presented to
T cells by murine H-2E or the homologous human HLA-DR molecules and that
lymphocytes lacking a functional H-2E molecule fail to respond to MAM.
Recently, more potent and purified preparations of MAM of known protein
content have become available. This enabled us to more effectively compare
the response of MAM with that of other SAgs by using lymphocytes from mice
whose cells express different H-2A and HLA- DQ molecules. Here we
demonstrate that cells from some H-2E-negative mouse strains respond to
higher concentrations of MAM. By use of inbred, congenic, and recombinant
mice, we show that these differences are, in fact, exercised at the level
of the major histocompatibility complex (MHC) and that allelic
polymorphisms at H-2A influence reactivity to MAM. In addition,
polymorphisms at HLA-DQ, the human homolog of H-2A, also influence
responsiveness to MAM. Cells expressing DQw6 (HLA-DQA1*0103 and DQBI*0601
chains) gave much higher responses to MAM than did cells expressing DQw8
(DQA1*0301 and DQB1*0302 chains). In fact, responses of lymphocytes
expressing DQB1*0601 chains homozygously were as high as those observed for
cells expressing a functional H-2E molecule. Murine lymphocytes responded
less well to staphylococcal enterotoxin B (SEB) and SEA, but mouse cells
expressing human MHC molecules gave much higher responses. The patterns of
reactivity observed with cells expressing the various murine and human
alleles differed for MAM, SEB, and SEA, suggesting that each of these SAgs
interacts with different regions or residues on MHC molecules. It has been
hypothesized that SAgs might play a role in susceptibility to autoimmune
disease. Allelic polymorphisms at MHC loci might therefore influence
susceptibility to autoimmune disease by affecting immunoreactivity to
specific superantigens.
Copyright © 1997, American Society for Microbiology
Allelic polymorphisms at the H-2A and HLA-DQ loci influence the response of murine lymphocytes to the Mycoplasma arthritidis superantigen MAM
Division of Rheumatology, University of Utah School of Medicine, Salt Lake City 84132, USA. barry.cole@hsc.utah.edu
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