Fine specificity of cellular immune responses in humans to human cytomegalovirus immediate-early 1 protein

N J Alp, T D Allport, J Van Zanten, B Rodgers, J G Sissons, L K Borysiewicz
1991 Journal of Virology  
Cell-mediated immunity is important in maintaining the virus-host equilibrium in persistent human cytomegalovirus (HCMV) infection. The HCMV 72-kDa major immediate early 1 protein (IE1) is a target for CD8+ cytotoxic T cells in humans, as is the equivalent 89-kDa protein in mouse. Less is known about responses against this protein by CD4+ T cells, which may be important as direct effector cells or helper cells for antibody and CD8+ responses. Proliferative-T-cell responses to HCMV IE1 were
more » ... ed in normal seropositive subjects. Peripheral blood mononuclear cells from 85% of seropositive subjects proliferated in response to HCMV from infected fibroblasts, and of these, 73% responded to recombinant baculovirus IEL. Responding cells were predominantly CD3+ CD4+. IEl antigen preparations, including baculovirus recombinant protein, transfected rat cell nuclei, and synthetic peptides, induced IEl-specific T-cell lines which cross-reacted between the preparations. The fine specificity of these IEl-specific T-cell lines was studied by using overlapping synthetic peptides encompassing the entire sequence of the IE1 protein. The regions of the IEl molecule recognized were identified and these varied between individuals, possibly reflecting differences in major histocompatibility complex (MHC) class II haplotype. In one subject, the peptide specificities of proliferative and MHC class I-restricted cytotoxic determinants on IE1 were spatially distinct. Thus, no single immunodominant T-cell determinant within HCMV IE1 was identified, suggesting that multiple peptides or a region of the 72-kDa TEl protein would be required to induce specific T-cell responses in humans. 4812 Vol. 65, No. 9 on May 7, 2020 by guest http://jvi.asm.org/ Downloaded from T-CELL RESPONSES TO HCMV IEl PROTEIN 4813 which were recognized varied between individuals, reflecting their diverse MHC class II haplotypes, and studies of one subject suggest that proliferative and cytotoxic determinants on IEl are spatially distinct. MATERIALS AND METHODS Cells and reagents. Cell cultures were grown in RPMI 1640 medium (Flow Laboratories Ltd., Irvine, Scotland) supplemented with 10% (vol/vol) Myoclone Plus fetal calf serum (GIBCO, Grand Island, N.Y.) or pooled human AB serum, 2.0 mM L-glutamine, 1.0 x 105 IU of penicillin per liter, and on May 7, 2020 by guest
doi:10.1128/jvi.65.9.4812-4820.1991 fatcat:5wt434uj2zgmzdwayi7lclzs74