title: Changes in CD45 isoform expression vary according to the duration of T-cell memory after vaccination.
abstract: Healthy young (< 40 years) and elderly (< 60 years) adults were immunized with the 1992-1993 preparation of trivalent influenza vaccine, and changes in CD45 isoform expression on peripheral blood lymphocytes were measured in the pre- and postvaccination periods. Fluorescence-activated cell sorter analysis was used to study T-cell subsets in fresh peripheral blood lymphocytes (day 0) and after 6 days of culture with live influenza virus. We have reported previously that the interleukin-2 response to the stimulating strain of virus, A/Texas/16/89, did not decline until 26 weeks postvaccination. In ex vivo CD4+ subsets, this interleukin-2 response was paralleled by a > 10% increase in the proportion of cells expressing the CD45RO+ phenotype following vaccination (p < 0.0001). In vitro stimulation had no effect on CD4+ subsets prior to vaccination but, after vaccination, was associated with a > 10% increase in CD45RA+RO+ cells (P < 0.0001). In addition, we have identified a change in the population of cells that express a CD45 isoform that is neither CD45RA nor CD45RO (CD45RA-RO-). At 26 weeks postvaccination, the proportion of CD45RA-RO- cells in ex vivo CD4+ peripheral blood mononuclear cells increased by approximately 15% from that measured at the earlier postvaccination time points (P < 0.0001). In vitro stimulation with influenza virus resulted in a further 20% increase in the proportion of CD45RA-RO- cells (P < 0.0001). The CD45RA-RO- phenotype may identify a population of cells undergoing apoptosis (programmed cell death) that limits the duration of helper T-cell (CD4+) memory after vaccination.
authors.affiliation: Department of Medicine, University of Alberta, Edmonton, Canada.
authors.forename: J E
authors.initials: JE
authors.lastname: McElhaney
authors.forename: M J
authors.initials: MJ
authors.lastname: Pinkoski
authors.forename: G S
authors.initials: GS
authors.lastname: Meneilly
mesh_terms: D000328:Adult; D000368:Aged; D017209:Apoptosis; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D005260:Female; D015870:Gene Expression; D006801:Humans; D007156:Immunologic Memory; D009980:Influenza A virus / Q000276:immunology; D007376:Interleukin-2 / Q000494:pharmacology; D017493:Leukocyte Common Antigens / Q000096:biosynthesis* / Q000235:genetics; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D013997:Time Factors; D014611:Vaccination
chemical_list: D007376:Interleukin-2; D017493:Leukocyte Common Antigens