Ungar-Waron H, Waron M, Gluckman A, Trainin Z
J Comp Pathol. 1985 Jul;95(3):399-403. doi: 10.1016/0021-9975(85)90044-1.
The occurrence of IgM-rheumatoid factors (RFs) was investigated in natural retrovirus infection of cats with feline leukaemia virus and of cattle with bovine leukaemia virus. IgM-RFs of polyclonal character were detected. No significant differences were observed between the amounts of IgM-RFs in the retrovirus-infected animals and their respective controls.