THE ACTIVATION STATUS OF OVINE CD45R(-) EFFERENT LYMPH T-CELLS AFTER ORF VIRUS REINFECTION() AND CD45R()

The dynamics and activation status of CD4(+) and CD8(+) T-cells differ entially expressing the CD45R (220 kDa) antigen were studied in prefem oral efferent lymph draining the site of cutaneous reinfection with or f virus. CD4(+), CD45R(+) lymphoblasts preceded CD4(+), CD45R(-) lymph oblasts during the first 48 h after reinfection. Thereafter, the outpu t of both total and blast-transformed CD4(+), CD45R(-) T-cells increas ed in proportion to the CD4 +, CD45R(+) cells for the duration of the virus reinfection. Output of CD8(+), CD45R(+) T-cells exceeded that of the CD8(+), CD45R(+) cells both before and after reinfection. However , within the lymphoblast population, CD8(+), CD45R(+) and CD8(+), CD45 R(-) T-cells increased and decreased in parallel. CD4(+), CD45R(-) and CD8(+), CD45R(-) T-cells produced interleukin-2, interferon-gamma and granulocyte-macrophage colony-stimulating factor after culture for 24 h without exogenous restimulation, whereas CD4(+), CD45R(+) T-cells p roduced only interleukin-2. The results show that although both CD45R( +) and CD45R(-) alpha beta receptor(+) T-cell subsets are activated as a consequence of virus reinfection in vivo, it is the CD45R(-) subset that predominates in the later stages of reinfection and is the princ ipal cellular source of lymphokines in the efferent lymph. (C) 1996 W. B. Saunders Company Limited