Hi Giorgio,
I think cappel/Organon Teknika should have your rabbit anit
mouse IgM. Telephon & Fax:
Organon Teknika S.p.A.
tel: (06) 701 921
fax: (06) 700 5059
If you are not successful with them, you can try dianova and
Molecular Probes.
Good luck
Gabriele