Impact of Kaposi sarcoma-associated herpesvirus (KSHV) burden and HIV coinfection on the detection of T cell responses to KSHV ORF73 and ORF65 proteins

Cellular immune responses to Kaposi sarcoma-associated herpesvirus (KSHV), the etiological agent of KS and several other malignancies, are incompletely characterized. We assessed KSHV-specific interferon- gamma enzyme-linked immunospot responses in a cohort of 154 individuals, using overlapping peptide sets spanning the KSHV-encoded latency-associated nuclear antigen (ORF73) and the minor capsid glycoprotein (ORF65). Among KSHV-seropositive subjects, ORF73-specific responses dominated over responses to ORF65 and were preferentially detected in human immunodeficiency virus-coinfected individuals who had elevated levels of cell-associated KSHV DNA, indicating that the viral antigen burden may have been driving these responses. Responses to both ORF73 and ORF65 were also detected in several KSHV-seronegative subjects who were at increased risk for KSHV infection, which demonstrates that cellular immunity can be found in the absence of detectable humoral responses. These data have implications for the reliable identification of KSHV infection and may help guide the design of immune-based therapeutic and prophylactic interventions.     

Molecular basis of altered red blood cell membrane properties in Southeast Asian ovalocytosis: role of the mutant band 3 protein in band 3 oligomerization and retention by the membrane skeleton

Southeast Asian ovalocytosis (SAO) is an asymptomatic trait characterized by rigid, poorly deformable red cells that resist invasion by several strains of malaria parasites. The underlying molecular genetic defect involves simple heterozygous state for a mutant band 3 protein, which contains a deletion of amino acids 400 through 408, linked with a Lys 56-to-Glu substitution (band 3-Memphis polymorphism). To elucidate the contribution of the mutant SAO band 3 protein to increased SAO red blood cell (RBC) rigidity, we examined the participation of the mutant SAO band 3 protein in increased band 3 attachment to the skeleton and band 3 oligomerization. We found first that SAO RBC skeletons retained more band 3 than normal cells and that this increased retention preferentially involved the mutant SAO band 3 protein. Second, SAO RBCs contained a higher percentage of band 3 oligomer-ankyrin complexes than normal cells, and these oligomers were preferentially enriched by the mutant SAO protein. At the ultrastructural level, the increased oligomer formation of SAO RBCs was reflected by stacking of band 3-containing intramembrane particles (IMP) into longitudinal strands. The IMP stacking was not reversed by treating SAO RBCs in alkaline pH (pH 11), which is known to weaken ankyrin-band 3 interactions, or by removing the cytoplasmic domain of band 3 from SAO membranes with trypsin. Finally, we found that band 3 protein in intact SAO RBCs exhibited a markedly decreased rotational mobility, presumably reflecting the increased oligomerization and the membrane skeletal association of the SAO band 3 protein. We propose that the mutant SAO band 3 has an increased propensity to form oligomers, which appear as longitudinal strands of IMP and exhibit increased association with membrane skeleton. This band 3 oligomerization underlies the increase in membrane rigidity by precluding membrane skeletal extension, which is necessary for membrane deformation.     

Impact of intrapeptide epitope location on CD8 T cell recognition: implications for design of overlapping peptide panels

BACKGROUND: Antigen-specific CD8 T cells following infection or immunization are typically assessed by measuring interferon-gamma production after stimulation with overlapping peptides spanning the region of interest. The effect of epitope location within such peptides is not known but may influence recognition. OBJECTIVE: To examine if peptides containing the appropriate C-terminal anchor amino acid residue would provide more sensitive detection of T cell responses. The impact was examined of epitope location within overlapping peptides on recognition of epitope-specific CD8 T cell responses. METHODS: C-terminal amino acid residues were analyzed in well-defined optimal epitopes for HIV, Epstein-Barr virus, cytomegalovirus and influenza and in peptide-binding motifs. Recognition of known epitopes within longer synthesized peptides by peripheral blood mononuclear cells or CD8 T cell lines was tested using interferon-gamma Elispot at various peptide concentrations. RESULTS: Only 9 of 20 amino acids served as the C-terminal anchor position in 96% of described optimal epitopes and in 95% of peptide-binding motifs. A CD8 T cell response to an epitope within a longer peptide is best detected when the epitope is situated at the C-terminal end of the longer peptide, both when using peptides designed to include the optimal epitope at every possible position and when comparing responses towards optimal epitopes and corresponding overlapping peptides in a larger group of subjects. CONCLUSION: When using overlapping peptides to screen for CD8 T cell responses, more sensitive detection will be achieved using known C-terminal anchor amino acid residues at the C-terminus.     

Immunohistochemical localization of membrane and alpha-granule proteins in human megakaryocytes: application to plastic-embedded bone marrow biopsy specimens

Using a new technique for antigen localization, we have demonstrated platelet proteins in megakaryocytes in plastic-embedded biopsy specimens of normal human bone marrow. In a series of 25 specimens, megakaryocytes showed labeling with antibodies to the integral membrane glycoproteins IIIa, IIb, and the IIb-IIIa complex; granule membrane protein 140; and five alpha-granule matrix proteins: thrombospondin, factor VIII-related antigen, beta-thromboglobulin, platelet factor 4, and fibrinogen. The antibodies to the membrane glycoproteins IIIa, IIb, and IIb-IIIa produced diffuse cytoplasmic staining and heavier staining on the plasma membrane, whereas the antibodies to the alpha-granule matrix proteins produced a distinct granular staining within the cytoplasm. Staining for granule membrane protein 140 was also granular in distribution. Rare mononuclear cells consistent with megakaryocyte precursors were labeled with these markers. Other enzyme histochemical and lectin-binding studies showed that the enzyme alpha-naphthyl acetate esterase, the lectin Ulex europaeus I, and the periodic-acid Schiff reaction were consistent, but not specific, markers of megakaryocytes. This immunohistochemical technique should facilitate the examination of qualitative and quantitative changes in megakaryocytes in a variety of physiologic and pathologic processes.     

Muscle architecture adaptations to knee extensor eccentric training: Rectus femoris vs. vastus lateralis

Introduction: Changes in muscle architecture induced by eccentric knee extensor training remain unclear, as well the adaptive responses of synergistic knee extensor muscles with different geometrical designs. Methods: Ultrasonography images were taken from rectus femoris (RF) and vastus lateralis (VL) of 20 male volunteers before and after a non‐training control period of 4 weeks, and additional evaluations were performed after 4, 8, and 12 weeks of isokinetic eccentric training. Results: RF and VL had significant changes in muscle architecture within the first 4 training weeks, and the adaptive response throughout the intervention was similar. Muscle thickness increased by around 7–10%, fascicle length increased 17–19%, and pennation angle was unchanged. Conclusions: Increased muscle thickness due to eccentric training was related to increased fascicle length and not to pennation angle changes. Although RF and VL have a different fascicular geometry, they had similar morphological adaptations to eccentric training. Muscle Nerve 48 : 498–506, 2013     

Native associations of early hematopoietic stem cells and stromal cells isolated in bone marrow cell aggregates

In suspensions of murine bone marrow, many stromal cells are tightly entwined with hematopoietic cells. These cellular aggregations appear to exist normally within the marrow. Previous studies showed that lymphocytes and stem cells adhered to stromal cells via vascular cell adhesion molecule 1 (VCAM1). Injection of anti-VCAM1 antibody into mice disrupts the aggregates, showing the importance of VCAM1 in the adhesion between stromal cells and hematopoietic cells in vivo. Early hematopoietic stem cells were shown to be enriched in aggregates by using a limiting-dilution culture assay. Myeloid progenitors responsive to WEHI-3CM in combination with stem cell factor (c-kit ligand) and B220- B-cell progenitors responsive to insulin-like growth factor-1 in combination with interleukin-7 are not enriched. We propose a scheme of stromal cell-hematopoietic cell interactions based on the cell types selectively retained within the aggregates. The existence of these aggregates as native elements of bone marrow organization presents a novel means to study in vivo stem cell-stromal cell interaction.