From the
Comm Svr: IP User's Guide and Commands manual
LS lists entries only for data sets and file types that FTP can process (see Appendix A, "Specifying data sets and files" in topic A.0 for a list). GDG base, VSAM, and ATL library entries are among the types not included in the LS output. See "DIr subcommand--Obtain a list of directory entries" in topic 5.18 to list entries for all types of data sets or files.
Since VSAM files (which would include ESDS of course) are not listed by the LS command, the implication is that FTP cannot handle VSAM files. Which, since VSAM files have structure as well as data, makes a lot of sense -- other platforms would not be able to deal with the structure. I do not believe you will be able to use FTP to directly transfer any VSAM file.