InVivoMAb anti-mouse MHC Class II (I-Ak, I-Ar, I-Af, I-As,I-Ag7)

Brown, K., et al. (2016). "Immunotoxin Against a Donor MHC Class II Molecule Induces Indefinite Survival of Murine Kidney Allografts" Am J Transplant 16(4): 1129-1138. PubMed

Rejection of donor organs depends on the trafficking of donor passenger leukocytes to the secondary lymphoid organs of the recipient to elicit an immune response via the direct antigen presentation pathway. Therefore, the depletion of passenger leukocytes may be clinically applicable as a strategy to improve graft survival. Because major histocompatibility complex (MHC) class II(+) cells are most efficient at inducing immune responses, selective depletion of this population from donor grafts may dampen the alloimmune response and prolong graft survival. In a fully MHC mismatched mouse kidney allograft model, we describe the synthesis of an immunotoxin, consisting of the F(ab’)2 fragment of a monoclonal antibody against the donor MHC class II molecule I-A(k) conjugated with the plant-derived ribosomal inactivating protein gelonin. This anti-I-A(k) gelonin immunotoxin depletes I-A(k) expressing cells specifically in vitro and in vivo. When given to recipients of kidney allografts, it resulted in indefinite graft survival with normal graft function, presence of Foxp3(+) cells within donor grafts, diminished donor-specific antibody formation, and delayed rejection of subsequent donor-type skin grafts. Strategies aimed at the donor arm of the immune system using agents such as immunotoxins may be a useful adjuvant to existing recipient-orientated immunosuppression.

in vitro MHC class II I-A blocking

Yang, T., et al. (2013). "Mapping I-A(g7) restricted epitopes in murine G6PC2" Immunol Res 55(1-3): 91-99. PubMed

G6PC2, also known as islet-specific glucose 6-phosphatase catalytic subunit-related protein (IGRP), is a major target of autoreactive CD8(+) T cells in both diabetic human subjects and the non-obese diabetic (NOD) mouse. However, in contrast to the abundant literature regarding the CD8(+) response to this antigen, much less is known about the potential involvement of IGRP-reactive CD4(+) T cells in diabetogenesis. The single previous study that examined this question in NOD mice was based upon a candidate epitope approach and identified three I-A(g7)-restricted epitopes that each elicited spontaneous responses in these animals. However, given the known inaccuracies of MHC class II epitope prediction algorithms, we hypothesized that additional specificities might also be targeted. To address this issue, we immunized NOD mice with membranes from insect cells overexpressing full-length recombinant mouse IGRP and measured recall responses of purified CD4(+) T cells using a library of overlapping peptides encompassing the entire 355-aa primary sequence. Nine peptides representing 8 epitopes gave recall responses, only 1 of which corresponded to any of the previously reported sequences. In each case proliferation was blocked by a monoclonal antibody to I-A(g7), but not the appropriate isotype control. Consistent with a role in diabetogenesis, proliferative responses to 4 of the 9 peptides (3 epitopes) were also detected in CD4(+) T cells purified from the pancreatic draining lymph nodes of pre-diabetic female animals, but not from peripheral lymph nodes or spleens of the same animals. Intriguingly, one of the newly identified spontaneously reactive epitopes (P8 [IGRP(55-72)]) is highly conserved between mice and man, suggesting that it might also be a target of HLA-DQ8-restricted T cells in diabetic human subjects, an hypothesis that we are currently testing.

in vitro MHC class II I-A blocking

Yang, H. Y., et al. (2010). "Rac/ROS-related protein kinase C and phosphatidylinositol-3-kinase signaling are involved in a negative regulating cascade in B cell activation by antibody-mediated cross-linking of MHC class II molecules" Mol Immunol 47(4): 706-712. PubMed

In addition to their essential role in antigen presentation, MHC class II molecules have been widely described as receptors associated with signal transduction involved in regulating B cell function. However, their precise function and mechanism in signal transduction are not yet fully elucidated. Our previous studies demonstrated that cross-linking of MHC class II molecules led to the inhibition of resting B cell activation in which various signal molecules were involved. Especially, Rac-associated ROS-dependent MAP kinases, including ERK1/2 and p38, are involved in MHC class II-associated negative signal transduction in the phorbol 12, 13-dibutyrate (PDBU)-treated, but not LPS-treated, resting B cell line, 38B9. In this study, we further illustrated that PKC regulates downstream signal molecules, including MAP kinases and NF-kappaB in PDBU-stimulated resting B cells, together with Rac and ROS. In addition, we found that phosphatidylinositol 3-kinase (PI3K)-dependent activation of ERK/p38 MAP kinases was associated with the signaling procedure in PDBU-induced B cell activation. Collectively, Rac/ROS-related PKC and PI3K signaling are involved in a negative regulation cascade through the cross-linking of MHC class II molecules by anti-MHC class II antibodies in resting B cells.

in vitro MHC class II I-A blocking

Li, H. S., et al. (2007). "Modifying effects of iodine on the immunogenicity of thyroglobulin peptides" J Autoimmun 28(4): 171-176. PubMed

We have previously shown that iodotyrosyl formation within thyroglobulin (Tg) generates neoantigenic determinants that are immunopathogenic. In the current study, we have examined iodination effects on three tyrosyl-containing Tg peptides that are immunogenic in their non-iodinated form. We found that iodotyrosyl formation can enhance (p179, a.a. 179-194), suppress (p2540, a.a. 2540-2554), or not alter (p2529, a.a. 2529-2545) the immunogenic profiles of these peptides at the T-cell level. On the other hand, iodination did not alter the MHC-restriction profile of p2529 and p2540 (A(k)-binders) or p179 (A(k)- and E(k)-binder) and did not significantly influence the pathogenicity of these determinants. At the B-cell level, addition of an iodine atom on Y192 in p179 generated a neoantigenic determinant, but analogous effects were not discernible in p2529 or p2540. Our results demonstrate that iodotyrosyl formation can exert variable effects on the immunogenic behavior of Tg epitopes which may not always result in enhanced pathology. These findings also suggest that variations in the iodine content of Tg may significantly alter the hierarchy of antigenic determinants, to which the immune system may or may not be tolerant.

in vitro MHC class II I-A expressing cell negative selection

Liu, Z. and T. M. Aune. (2006). "Deregulated stress system in non-obese diabetic lymphocyte" Genes Immun 7(5): 352-358. PubMed

Lymphopenia-induced homeostatic expansion in non-obese diabetic (NOD) mice may lead to autoimmunity. We demonstrated that NOD lymphocytes are more susceptible to apoptosis than those of non-diabetic C57BL/6 or NOD.H2(h4) mice in vivo and in vitro, which may be an underlying mechanism causing lymphopenia in NOD mice. Gene expression profiling identified a set of genes that are differentially expressed between NOD and B6 mice. Identity of these genes suggested that NOD T cells have a deregulated stress response system, especially heat-shock protein family, making them overly sensitive to apoptosis. Thus, we hypothesize that this strain-specific gene expression profile may confer a liability upon NOD T cells making them more susceptible to apoptosis that may lead to lymphopenia in NOD mice and contribute to development of autoimmunity.