FIG. 6.

Cytolytic activity of pulmonary T lymphocytes. (A) Kinetics of cytolytic activity in lung infiltrates as determined by CD3ɛ-redirected lysis for an effector/target cell ratio (E/T) of 100, with P815 mastocytoma cells as targets. Dots represent results compiled from independent but analogous transplantations. The median values are marked by dashes. The shaded area represents the activity measured with pulmonary lymphocytes recovered from lung tissue 4 weeks after BMT with no infection. This activity never exceeded the upper 95% confidence limit of the spontaneous lysis measured in the absence of effector cells. To serve as a positive reference, CD3ɛ-redirected lysis and murine CMV IE1 peptide-specific lysis are compared for an IE1 peptide-specific long-term CTLL in the insets. (B) Kinetics of the IE1 peptide-specific cytolytic activity in lung infiltrates for an E/T of 100. Target cells were P815 pulsed with a saturating concentration [10⁻⁸ M] of the synthetic IE1 peptide, a nonapeptide of the sequence YPHFMPTNL. Symbols are as described for panel A. IE1 peptide dose dependence of IE1-specific cytolytic activity of pulmonary effector cells recovered 4 weeks after BMT and infection is shown in the left inset. P815-B7 transfectants and parental P815 served as target cells at an E/T of 100. Titration of the pulmonary effector cells is shown in the right inset. Target cells were pulsed with a saturating concentration [10⁻⁸ M] of synthetic IE1 peptide.