Prevalent and immunodominant CD8 T cell epitopes are conserved in SARS-CoV-2 variants.

The emergence of SARS-CoV-2 variants of concern (VOC) is driven by mutations that mediate escape from neutralizing antibodies. There is also evidence that mutations can cause loss of T cell epitopes. However, studies on viral escape from T cell immunity have been hampered by uncertain estimates of epitope prevalence.

Rituximab-treated patients with lymphoma develop strong CD8 T-cell responses following COVID-19 vaccination.

B-cell depletion induced by anti-cluster of differentiation 20 (CD20) monoclonal antibody (mAb) therapy of patients with lymphoma is expected to impair humoral responses to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) vaccination, but effects on CD8 T-cell responses are unknown. Here, we investigated humoral and CD8 T-cell responses following two vaccinations in patients with lymphoma undergoing anti-CD20-mAb therapy as single agent or in combination with chemotherapy or other anti-neoplastic agents during the last 9 months prior to inclusion, and in healthy age-matched blood donors. Antibody measurements showed that seven of 110 patients had antibodies to the receptor-binding domain of the SARS-CoV-2 Spike protein 3-6 weeks after the second dose of vaccination.

Identification of MHC Class Ib Ligands for Stimulatory and Inhibitory Ly49 Receptors and Induction of Potent NK Cell Alloresponses in Rats.

Early studies indicate that rats may have a repertoire of MHC class Ib-reactive Ly49 stimulatory receptors capable of mounting memory-like NK cell alloresponses. In this article, we provide molecular and functional evidence for this assumption. Pairs of Ly49 receptors with sequence similarities in the lectin-like domains, but with opposing signaling functions, showed specificity for ligands with class Ia-like structural features encoded from the first telomeric MHC class Ib gene cluster, , which is syntenic with the cluster in mice.

Degranulation Response in Cytotoxic Rat Lymphocytes Measured with a Novel CD107a Antibody.

Measuring degranulation through CD107a expression has become an advantageous tool for testing the functional capacity of cytotoxic cells. Such functional studies have been hampered in the rat by the lack of a suitable anti-rat CD107a antibody. In this study, we report a novel hybridoma generated by immunizing Armenian inbred hamsters with transfected Chinese hamster ovary cells expressing CD107a.

Identification of an MHC class I ligand for the single member of a killer cell lectin-like receptor family, KLRH1.

Natural killer cells are able to recognize and kill target cells according to differences in MHC class I expression. In rodents, the Ly49 receptors are primarily responsible for this MHC differentiation. We previously described the cloning of a novel C-type lectin-like receptor, KLRH1, encoded in the NK complex adjacent to the Ly49 genes and expressed by subsets of NK and NKT cells.

Phylogenetic and functional conservation of the NKR-P1F and NKR-P1G receptors in rat and mouse.

Two clusters of rat Nkrp1 genes can be distinguished based on phylogenetic relationships and functional characteristics. The proximal (centromeric) cluster encodes the well-studied NKR-P1A and NKR-P1B receptors and the distal cluster, the largely uncharacterized, NKR-P1F and NKR-P1G receptors. The inhibitory NKR-P1G receptor is expressed only by the Ly49s3(+) NK cell subset as detected by RT-PCR, while the activating NKR-P1F receptor is detected in both Ly49s3(+) and NKR-P1B(+) NK cells.

The rat NK cell receptors Ly49s4 and Ly49i4 recognize nonclassical MHC-I molecules on Listeria monocytogenes-infected macrophages.

Ly49 receptors in rodents, like KIRs in humans, regulate NK cell activity. Although inhibitory Ly49 receptors clearly recognize MHC-I molecules, ligands for the activating Ly49 receptors are less well defined. Here, we show that the activating Ly49s4 and the inhibitory Ly49i4 receptors recognize nonclassical MHC-I molecules on the rat macrophage cell line R2 (RT1(d)).

The activating rat Ly49s5 receptor responds to increased levels of MHC class Ib molecules on Listeria monocytogenes-infected enteric epithelial cells.

We have investigated whether rat Ly49 receptors can monitor Listeria-infected intestinal epithelial cells through altered expression of MHC class I molecules. The rat colon carcinoma epithelial cell line CC531 infected with Listeria expressed higher levels of both classical and nonclassical MHC-I molecules. Reporter cells expressing the activating Ly49s5 receptor displayed increased stimulatory responses when incubated with Listeria-infected CC531 cells in vitro, which could be blocked with mAb 8G10 specific for nonclassical MHC-I molecules of the RT1(u) haplotype, but not with mAb OX18 reacting with classical MHC-I molecules in this haplotype.

Two major groups of rat NKR-P1 receptors can be distinguished based on chromosomal localization, phylogenetic analysis and Clr ligand binding.

A major subset of non-alloreactive NK cells in PVG strain rats is generally low in Ly49 receptors, but expresses the rat NKR-P1B(PVG) receptor (previously termed NKR-P1C). The NKR-P1B(+) NK subset is inhibited by a non-polymorphic target cell ligand, which we have shown here to be a C-type lectin-related molecule (Clr). Clr11 ligates two divergent NKR-P1B alleles as judged by an NFAT-driven reporter assay, and inhibits NK-cell cytotoxicity of NKR-P1B(+) NK cells.

A second prophylactic MHC-mismatched bone marrow transplantation protects against rat acute myeloid leukemia (BNML) without lethal graft-versus-host disease.

Background: We have employed a rat model for human acute myeloid leukemia, a promyelocytic leukemia in the BN rat strain (BNML), to develop new protocols for immunotherapy in combination with allogeneic bone marrow transplantation (alloBMT). The status of mixed chimerism in allotransplanted rats provided an opportunity for immunotherapy using alloreactive donor cells. In addition to T or natural killer (NK) cells, we introduced a second infusion of bone marrow cells as prophylactic donor lymphocyte infusions (DLI) to test whether an effective graft-versus-leukemia (GVL) response could be obtained without clinical graft-versus-host disease (GVHD).

Expression of SH2D2A in T-cells is regulated both at the transcriptional and translational level.

The T-cell specific adapter protein (TSAd) encoded by the SH2D2A gene is up-regulated in activated human CD4+ T-cells in a cAMP-dependent manner. Expression of SH2D2A is important for proper activation of T-cells. Here, we show that SH2D2A expression is regulated both at the transcriptional and translational level.

Strain-dependent expression of four structurally related rat Ly49 receptors; correlation with NK gene complex haplotype and NK alloreactivity.

Natural killer (NK) cells from certain rat strains promptly kill MHC allogeneic lymphocytes in vivo, a rejection phenomenon termed allogeneic lymphocyte cytotoxicity (ALC). ALC can be reproduced in vitro, and is preferentially mediated by a subset of NK cells expressing the Ly49 stimulatory receptor 3 (Ly49s3) in PVG strain rats. Functional studies have suggested that Ly49s3 triggers NK cell alloreactivity, but its importance relative to other Ly49 receptors has not been investigated.

Structure function analysis of SH2D2A isoforms expressed in T cells reveals a crucial role for the proline rich region encoded by SH2D2A exon 7.

Background: The activation induced T cell specific adapter protein (TSAd), encoded by SH2D2A, interacts with and modulates Lck activity. Several transcript variants of TSAd mRNA exist, but their biological significance remains unknown. Here we examined expression of SH2D2A transcripts in activated CD4+ T cells and used the SH2D2A variants as tools to identify functionally important regions of TSAd.

The novel inhibitory NKR-P1C receptor and Ly49s3 identify two complementary, functionally distinct NK cell subsets in rats.

The proximal region of the NK gene complex encodes the NKR-P1 family of killer cell lectin-like receptors which in mice bind members of the genetically linked C-type lectin-related family, while the distal region encodes Ly49 receptors for polymorphic MHC class I molecules. Although certain members of the NKR-P1 family are expressed by all NK cells, we have identified a novel inhibitory rat NKR-P1 molecule termed NKR-P1C that is selectively expressed by a Ly49-negative NK subset with unique functional characteristics. NKR-P1C(+) NK cells efficiently lyse certain tumor target cells, secrete cytokines upon stimulation, and functionally recognize a nonpolymorphic ligand on Con A-activated lymphoblasts.

Two structurally related rat Ly49 receptors with opposing functions (Ly49 stimulatory receptor 5 and Ly49 inhibitory receptor 5) recognize nonclassical MHC class Ib-encoded target ligands.

The Ly49 family of lectin-like receptors in rodents includes both stimulatory and inhibitory members. Although NK alloreactivity in mice is regulated primarily by inhibitory Ly49 receptors, in rats activating Ly49 receptors are equally important. Previous studies have suggested that activating rat Ly49 receptors are triggered by polymorphic ligands encoded within the nonclassical class Ib region of the rat MHC, RT1-CE/N/M, while inhibitory Ly49 receptors bind to widely expressed classical class Ia molecules encoded from the RT1-A region.

Microbial colonization induces oligoclonal expansions of intraepithelial CD8 T cells in the gut.

Two populations of CD8(+) IEL generally express restricted, but apparently random and non-overlapping TCR repertoires. Previous studies in mice suggested that this could be explained by a dual origin of CD8(+) IEL, i.e.

Transcriptional activation of the SH2D2A gene is dependent on a cyclic adenosine 5'-monophosphate-responsive element in the proximal SH2D2A promoter.

The SH2D2A gene, encoding the T cell-specific adapter protein (TSAd), is rapidly induced in activated T cells. In this study we investigate the regulation of the SH2D2A gene in Jurkat T cells and in primary T cells. Reporter gene assays demonstrated that the proximal 1-kb SH2D2A promoter was constitutively active in Jurkat TAg T cells and, to a lesser extent, in K562 myeloid cells, Reh B cells, and 293T fibroblast cells.