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Lack of response to HBsAg is due to a defect in T cells
Abstracts
35
B-3.1 #57
LACK OF RESPONSE TO HBsAg IS DUE TO A DEFECT IN T CELLS. H Deulofeut, EJ Yunis R Deulofeut, M Salazar, MS Kruskall, DE Yunis, D Marcus-Bagley, Z Awdeh and CA Alper, The Center for Blood Research and the Dana-Farber Cancer Inst., Boston, MA. Standard immunization with HBsAg results in immune responses measured by specific antibody production and T cell responses. The antibody response is defective in -4.6% of caucasians, particularly in homozygotes for [HLA-B8, SC01, DR3] and [HLA-B44, FC31, DR7]. In the present study, the cellular basis for non-response was investigated by examining the antigen presentation capacity of antigen presenting cells (APC) from responders and nonresponders to HBsAg. HLA identical pairs of individuals who were discordant for response to HBsAg were selected for study by assessing antibody production, lymphocyte proliferation and autologous antigen presentation specific to HBsAg. All individuals received a booster vaccination of HBsAg and tetanus toxoid prior to the study. Specificity of the lack of response to HBsAg was demonstrated by the ability of nonresponders to respond to tetanus toxoid. Using heterologous antigen presentation assays with APC and purified T cells from responders and nonresponders, we studied cell mixtures with APC from nonresponders previously pulsed with HBsAg and T cells of responder individuals as well as APC from responder individuals presenting the antigen to nonresponder T cells. Lymphocytes from each pair were nonreactive in the mixed lymphocyte reaction (MLR). Results obtained from 4 different pairs of HLA identical individuals demonstrated that T cells from responders proliferated to HBsAg when presented by APC derived from non-responder individuals. In contrast, T cells from nonresponders failed to proliferate when HBsAg was presented by APC derived from responder individuals or by their autologous APC. These results demonstrate that APC from nonresponder individuals are capable of adequately processing and presenting HBsAg and that the cellular basis of the lack of response to HBsAg is likely to be due to a defect in T cells.
B-3.1 #58
N A T U R A L L Y PROCESSED PEPTIDES BOUND TO MAJOR HISTOCOMPATABILITY COMPLEX CLASS II. p, Harris, A.Maffei, Z. Liu, A. Colovai, E. Reed, G. Inghirami and N. Suciu-Foca, Department of Pathology, Columbia University, New York, NY. The recognition of self-peptides bound to MHC is likely to be a key feature for immune surveillance, tolerance, and regulation. A series of I-ILA DR2 and DR5 bound self-peptides were isolated from an EBV-transformed lymphoblastoid B cell line (LBCL-SW) by immunoaffinity purification. The pool of peptides released by heat denaturation and ultrafiltration were separated by HPLC and the fractions containing peptides were sequenced by automated Edrnan degradation. Two distinct peptide motifs could be assigned. One of them displayed ragged ends and conserved residues at positions i (valine), i+l (tyrosine), and i+5 (lysine or arginine). The second motif showed an unexpected uniformity of N-terminii with conserved proline constantly present in position 2, and a basic residue (lysine or arginine) in position 9. This motif could be attributed to DR5 by sequence homology with previously reported peptides. One of the peptides from the first group showed 100% homology to the variable region of the Ig heavy chain expressed by the LBCL-SW, as it was shown by cDNA sequencing. This finding reinforces the concept that Ig idiotypes can be presented by MHC Class II molecules and thus recognized by T helper cells. A second peptide matched 100% to LD78 gene product, the human equivalent of murine macrophage inhibitory protein. According to the motif displayed, the peptide had been bound to DR5 molecules. We have studied the effect of synthetic version of the LD78 peptide on HLA DR5 restricted T cell recognition. The T cell response was found to be inhibited by the peptide, suggesting that activation-induced cytokines could generate peptides that may inhibit T cell activation.
35
B-3.1 #57
LACK OF RESPONSE TO HBsAg IS DUE TO A DEFECT IN T CELLS. H Deulofeut, EJ Yunis R Deulofeut, M Salazar, MS Kruskall, DE Yunis, D Marcus-Bagley, Z Awdeh and CA Alper, The Center for Blood Research and the Dana-Farber Cancer Inst., Boston, MA. Standard immunization with HBsAg results in immune responses measured by specific antibody production and T cell responses. The antibody response is defective in -4.6% of caucasians, particularly in homozygotes for [HLA-B8, SC01, DR3] and [HLA-B44, FC31, DR7]. In the present study, the cellular basis for non-response was investigated by examining the antigen presentation capacity of antigen presenting cells (APC) from responders and nonresponders to HBsAg. HLA identical pairs of individuals who were discordant for response to HBsAg were selected for study by assessing antibody production, lymphocyte proliferation and autologous antigen presentation specific to HBsAg. All individuals received a booster vaccination of HBsAg and tetanus toxoid prior to the study. Specificity of the lack of response to HBsAg was demonstrated by the ability of nonresponders to respond to tetanus toxoid. Using heterologous antigen presentation assays with APC and purified T cells from responders and nonresponders, we studied cell mixtures with APC from nonresponders previously pulsed with HBsAg and T cells of responder individuals as well as APC from responder individuals presenting the antigen to nonresponder T cells. Lymphocytes from each pair were nonreactive in the mixed lymphocyte reaction (MLR). Results obtained from 4 different pairs of HLA identical individuals demonstrated that T cells from responders proliferated to HBsAg when presented by APC derived from non-responder individuals. In contrast, T cells from nonresponders failed to proliferate when HBsAg was presented by APC derived from responder individuals or by their autologous APC. These results demonstrate that APC from nonresponder individuals are capable of adequately processing and presenting HBsAg and that the cellular basis of the lack of response to HBsAg is likely to be due to a defect in T cells.
B-3.1 #58
N A T U R A L L Y PROCESSED PEPTIDES BOUND TO MAJOR HISTOCOMPATABILITY COMPLEX CLASS II. p, Harris, A.Maffei, Z. Liu, A. Colovai, E. Reed, G. Inghirami and N. Suciu-Foca, Department of Pathology, Columbia University, New York, NY. The recognition of self-peptides bound to MHC is likely to be a key feature for immune surveillance, tolerance, and regulation. A series of I-ILA DR2 and DR5 bound self-peptides were isolated from an EBV-transformed lymphoblastoid B cell line (LBCL-SW) by immunoaffinity purification. The pool of peptides released by heat denaturation and ultrafiltration were separated by HPLC and the fractions containing peptides were sequenced by automated Edrnan degradation. Two distinct peptide motifs could be assigned. One of them displayed ragged ends and conserved residues at positions i (valine), i+l (tyrosine), and i+5 (lysine or arginine). The second motif showed an unexpected uniformity of N-terminii with conserved proline constantly present in position 2, and a basic residue (lysine or arginine) in position 9. This motif could be attributed to DR5 by sequence homology with previously reported peptides. One of the peptides from the first group showed 100% homology to the variable region of the Ig heavy chain expressed by the LBCL-SW, as it was shown by cDNA sequencing. This finding reinforces the concept that Ig idiotypes can be presented by MHC Class II molecules and thus recognized by T helper cells. A second peptide matched 100% to LD78 gene product, the human equivalent of murine macrophage inhibitory protein. According to the motif displayed, the peptide had been bound to DR5 molecules. We have studied the effect of synthetic version of the LD78 peptide on HLA DR5 restricted T cell recognition. The T cell response was found to be inhibited by the peptide, suggesting that activation-induced cytokines could generate peptides that may inhibit T cell activation.