Short-term hyperglycemia depresses immunity through nonenzymatic glycosylation of circulating immunoglobulin

Hyperglycemia accompanies a myriad of clinical conditions and causes an acceleration in the nonenzymatic glycosylation (NEG) of proteins. Since many proteins lose function when glycosylated, we assessed the effect of hyperglycemia on the function of immunoglobulin G. Twenty newborn Sprague-Dawley rats underwent splenectomy and 20, splenic mobilization alone. After 3 weeks, all animals received an intraperitoneal injection of Streptococcus pneumoniae. Twelve hours later, ten animals from each group received either control (CIG) or glycosylated (GIG) human immunoglobulin (0.3 gm/kg) intraperitoneally. Asplenic animals receiving GIG lived 28.5 hours vs. 49.6 hours for those receiving CIG (p less than 0.0001). Animals with spleens receiving GIG lived 48.2 hours vs. 51.7 hours for those receiving CIG (p = 0.03). Short-term glycosylation of immunoglobulin causes its inactivation. This may contribute to the increased risk of infection noted in hyperglycemic animals.     

No regression of renal AL amyloid in monoclonal gammopathy after successful autologous blood stem cell transplantation and significant clinical improvement.

BACKGROUND: High-dose chemotherapy followed by autologous blood stem cell transplantation induces remission of plasma cell dyscrasia in patients with AL amyloidosis. The impact of this treatment on the glomerular amyloid mass is still unknown. METHODS: In the present study, the quantity of the renal amyloid mass before and more than 3 years after high-dose melphalan treatment and autologous blood stem cell transplantation was assessed in two patients. At the time of the second renal biopsy, both patients were in complete remission without detectable serum and urinary monoclonal IgA-lambda and a normal percentage of plasma cells in the bone marrow. RESULTS: In both patients with biopsy-proven AL amyloidosis, urinary protein excretion decreased from 7 g/24 h to <2 g/24 h more than 3 years after autologous blood stem cell transplantation. In contrast, glomerular amyloid deposits persisted, as shown in the second biopsy. CONCLUSION: Despite complete remission of the plasma cell dyscrasia and improvement of glomerular permeability, the amount of glomerular amyloid mass did not regress.     

Competitive control of the self-renewing T cell repertoire

We develop a mathematical model for the self-renewing part of the T cell repertoire. Assuming that self-renewing T cells have to be stimulated by immunogenic MHC-peptide complexes presented on the surfaces of antigen-presenting cells, we derive a model of T cell growth in which competition for MHC-peptide complexes limits T cell clone sizes and regulates the total number of self-renewing T cells in the animal. We show that for a sufficient diversity and/or degree of cross-reactivity, the total T cell number hardly depends upon the diversity of the T cell repertoire or the diversity of the set of presented peptides. Conversely, for repertoires of lower diversity and/or cross-reactivity, steady-state total T cell numbers may be limited by the diversity of the T cells. This provides a possible explanation for the limited repertoire expansion in some, but not all, mouse T cell re-constitution experiments. We suggest that the competitive interactions described by our model underlie the normal T cells numbers observed in transgenic mice, germ-free mice and various knockout mice.      

Localization of a gene for otosclerosis to chromosome 15q25-q26

Among white adults otosclerosis is the single most common cause of hearing impairment. Although the genetics of this disease are controversial, the majority of studies indicate autosomal dominant inheritance with reduced penetrance. We studied a large multi- generational family in which otosclerosis has been inherited in an autosomal dominant pattern. Five of16 affected persons have surgically confirmed otosclerosis; the remaining nine have a conductive hearing loss but have not undergone corrective surgery. To locate the disease- causing gene we completed genetic linkage analysis using short tandem repeat polymorphisms (STRPs) distributed over the entire genome. Multipoint linkage analysis showed that only one genomic region, on chromosome 15q, generated a lod score >2.0. Additional STRPs were typed in this area, resulting in a lod score of 3.4. STRPs FES (centromeric) and D15S657 (telomeric) flank the 14. 5 cM region that contains an otosclerosis gene.