Immune cell infiltration in corneas of mice with recurrent herpes simplex virus disease

Reactivation of latent herpes implex virus type 1 (HSV-1) infection was induced by UV irradiation of the corneas of latently infected mice. On days 1--4 after stimulation, infectious virus was sought in nervous and ocular tissue. On days 4, 7 and 10, eyes with either recurrent epithelial or stromal disease and appropriate controls were stained to identify immune cells and HSV-1 antigens. The maximum incidence of infectious virus was on day 2 when 5/10 ophthalmic parts of the trigeminal ganglion yielded HSV. Thus in this mouse model, as in humans, reactivation of virus in the trigeminal ganglion is the likely source of virus producing recurrent disease and shedding in the tear film. On day 4, when virus antigens were still present, granulocytes were the predominant infiltrating cell in corneas with either type of disease. Small numbers ofT cells, dendritic cells and cells expressing MHC class II were also present. In stromal disease, the granulocyte infiltrate persisted and T cells remained sparse. In contrast, in epithelial disease, granulocyte numbers rapidly declined and both CD4 + and CD8 + T cells (present at a ratio of 1:1) increased significantly. The secondary immune response to virus antigen is more rapid and vigorous than that during primary corneal infection. Granulocytes may play a role in the initial clearance of virus, however, the other types of cells present early on provide the potential for a local secondary immune response. The high proportion of CD8 ÷ cells in epithelial disease compared with stromal disease suggests that they may be acting as suppressors

Protection of non-obese diabetic mice from autoimmune diabetes by Escherichia coli heat-labile enterotoxin B subunit

Autoimmune diabetes in the non-obese diabetic (NOD) mouse is associated with development of inflammation around the islets at around 4–5 weeks of age, which may be prolonged until frank diabetes begins to occur around 12 weeks of age. Although many interventions can halt disease progression if administration coincides with the beginning of the anti-β cell response, very few are able to prevent diabetes development once insulitis is established. Here we describe a strategy which blocks cellular infiltration of islets and prevents diabetes. Intranasal treatment with the B-subunit of Escherichia coli heat labile enterotoxin (EtxB), a protein that binds GM1 ganglioside (as well as GD1b, asialo-GM1 and lactosylceramide with lower affinities), protected NOD mice from developing diabetes in a receptor-binding dependent manner. Protection was associated with a significant reduction in the number of macrophages, CD4(+) T cells, B cells, major histocompatibility complex class II(+) cells infiltrating the islets. Despite this, treated mice showed increased number of interleukin-10(+) cells in the pancreas, and a decrease in both T helper 1 (Th1) and Th2 cytokine production in the pancreatic lymph node. Disease protection was also transferred with CD4(+) splenocytes from treated mice. Taken together, these results demonstrated that EtxB is a potent immune modulator capable of blocking diabetes

Abortive activation precedes functional deletion of CD8(+) T cells following encounter with self-antigens expressed by resting B cells in vivo

InsHA mice express the haemagglutinin (HA) protein from influenza virus A/PR/8 H1N1 (PR8) as a self antigen on pancreatic islet β cells. We have utilized these mice to investigate the ability of resting B cells expressing K(d) to induce self-tolerance among naive K(d)HA-specific clone 4 CD8(+) T cells. Adoptive transfer of K(d)HA-peptide-pulsed resting B cells into clone 4 → InsHA recipients resulted in the activation and proliferation of clone 4 CD8(+) T cells throughout the peripheral lymphoid tissues. Significantly, proliferation was not associated with the acquisition of T cell effector function; as evidenced by a lack of interferon-γ production and the complete absence of any autoimmune pathology even after immunization of recipient mice with PR8. These data demonstrate that resting B cells pulsed with self-epitopes can induce abortive activation of potentially self-reactive naive CD8(+) T cells resulting in their functional deletion from the peripheral T-cell repertoire in the absence of any associated autoimmunity