EXPRESSION OF MHC CLASS II ANTIGEN, INTERLEUKIN‐2 RECEPTOR, TRANSFERRIN RECEPTOR AND GP 40/80 GLYCOPROTEIN DURING DIFFERENT PHASES OF A NORMAL PHA‐DRIVEN LYMPHOCYTE ACTIVATION IN VITRO

This study characterizes the temporal profile of MHC class II antigen, interleukin-2 receptor, transferrin receptor and gp 40/80 glycoprotein lymphocyte activation markers in relation to each other during different phases of PHA-dependent cellular activation in vitro. Binding of these monoclonal lymphocyte activation-probes was visualized by the avidin-biotin-peroxidase complex method. Maximum PHA-dependent MHC class II antigen expression of 27 +/- 3% was observed on culture day 1, but later no significant differences were observed in MHC class II antigen expression between PHA-driven or culture media-containing control cultures. On the contrary, interleukin-2 receptor (78 +/- 6%) and transferrin receptor (75 +/- 5%) expression reached a maximum on culture day 3, coinciding with a maximum proliferative response. On culture day 5, when 3H-thymidine incorporation was already on the decline, gp 40/80 glycoprotein reached a maximum PHA-dependent expression of 78 +/- 2%, which differed significantly from interleukin-2 receptor (60 +/- 8%, p less than 0.05) and transferrin receptor (51 +/- 8%, p less than 0.01) expression. This study suggests that MHC class II antigen, interleukin-2 receptor, transferrin receptor and gp 40/80 glycoprotein, although all of them are lymphocyte-activation markers, differ as to the chronological sequence of their appearance and disappearance. Their combined use in lymphocyte-activation marker profile assay therefore gives valuable information about the lymphocyte activation state.