Epstein-Barr virus (EBV) latent membrane protein 1 (LMP 1) is expressed in Hodgkin and Reed-Sternberg (HRS) cells in about one half of Hodgkin's disease (HD) cases. In vitro, LMP 1 induces B-cell expression of CD23 antigen, ICAM-1 and LFA-3. To evaluate the influence of LM P 1 on the expression of these molecules in HRS cells in vivo, we performed a quantitative frozen section immunohistological study comparing the numerical density (cells per unit area) of HRS cells expressing the CD23 antigen, ICAM-1 and LFA-3 in 14 LMP 1-positive and 13 LMP 1-negative HD cases. CD23 antigen was demonstrated in HRS cells in five LMP 1-positive and three LMP 1-negative cases (not significant). The relative density of HRS cells tended to be lower in the LMP 1-positive than in the LMP 1-negative cases, but this did not reach significance (0.2>2p>0.1). All recognizable HRS cells expressed ICAM-1 and LFA-3 irrespective of LMP 1 status. We conclude that expression of CD23 antigen and LMP 1 are not coordinated in HD. Although LMP 1 may have some influence on CD23 antigen expression, it is unlikely that the latter is of importance in the putative EBV induced growth transformation of HRS cells in vivo.