The IA antigen is not the major receptor for lactate dehydrogenase-elevating virus on macrophages from CBA and BALB/c mice

Abstract

Double staining and labeling procedures were employed to simultaneously identify IA + cells and cells permissive for the replication of the lactate dehydrogenaseelevating virus (LDV) in populations of peritoneal and spleen macrophages from BALB/c and CBA/J mice. No correlation between the expression of IA antigen and LDV permissiveness was observed. Only a low proportion of resident peritoneal macrophages expressed IA antigen and the antigen was lost within 1–2 days in culture whether or not L cell-conditioned medium was present, whereas the cells retained undiminished LDV permissiveness for 4 days and longer. Induction of IA expression on macrophages by injection of mice with concanavalin A, starch or indomethacin (up to 50% of the total macrophages became IA +), or elimination of IA + macrophages by treatment with anti-IA monoclonal antibodies plus complement had little or no effect on the ability of the cells to support LDV replication in vivo or in vitro. LDV infection of untreated or concanavalin A-treated or starchtreated mice caused a drastic decline in IA + peritoneal macrophages within 1 day, but the number of IA + macrophages returned to pre-infection levels by 7 days post-infection without rendering the cells LDV permissive. Treatment of macrophages with trypsin destroyed the LDV receptor on macrophages with minimal loss of IA antigen from the cells. We conclude that the IA antigen is not the major receptor for infection of macrophages from BALB/c or CBA mice by LDV.