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Antigen-specific T helper cells present in peripheral blood at very low frequencies are capable of rapid clonal expansion during antigenic challenge. The exquisite specificity of this response provides for activation and expansion of a very select cohort of T cells, a feature we have used to directly identify and quantify human epitope-specific T helper(More)
T cell responses to Ags involve recognition of selected peptide epitopes contained within the antigenic protein. In this report, we describe a new approach for direct identification of CD4+ T cell epitopes of complex Ags that uses human class II tetramers to identify reactive cells. With a panel of 60 overlapping peptides covering the entire sequence of the(More)
Antigen-specific T cells acquire a distinctive phenotype during activation, with characteristic acquisition of surface markers and patterns of gene expression. Early after antigen stimulation, CD4(+) T lymphocytes increase their surface density of the CD4 marker, a trait which has been used to identify antigen-activated cells. The recent development of MHC(More)
Plasticity of TCR interactions during CD4(+) T cell activation by an MHC-peptide complex accommodates variation in the peptide or MHC contact sites in which recognition of an altered ligand by the T cell can modify the T cell response. To explore the contribution of this form of TCR cross-recognition in the context of T cell selection on disease-associated(More)
Ag-specific CD4+ T cells are present in peripheral blood in low frequency, where they undergo recruitment and expansion during immune responses and in the pathogenesis of numerous autoimmune diseases. MHC tetramers, which constitute a labeled MHC-peptide ligand suitable for binding to the Ag-specific receptor on T cells, provide a novel approach for the(More)
In a double-blind study with randomly assigned topical solutions of 0%, 1%, 3%, or 5% minoxidil, the blood flow in balding scalps of 16 human volunteers was measured by the noninvasive techniques of both laser Doppler velocimetry (LDV) and photopulse plethysmography (PPG). On two consecutive days, an 0.25-ml volume of the assigned minoxidil formulation was(More)
Approximately 90% of 67 multi-transfused patients with bleeding disorders were positive either for anti-HBs (85%) or HBsAg (45%). Using a polyethylene glycol trypsinization assay, we found anti-HbsAg-containing specific circulating immune complexes (HBsAg-CICs) in 3 of the 57 HBsAg-negative haemophiliacs possessing anti-HBs. The occurrence of HBsAg-CICs may(More)
An antigen-specific method has been developed for direct detection and quantitation of HBsAg-ICs. The method involves (1) precipitation of HBsAg-ICs with 3.5% PEG; (2) dissociation of the PEG precipitated ICs by treatment with NaSCN, NaI, KBr, low or high pH buffers, trypsin or papain; and (3) detection and titration of HBsAg and/or anti-HBs liberated from(More)