Abstract
Samples of serum and testicular fluid from normal rabbits and those infected with T. pallidum were examined for total protein, albumin, IgG and IgM concentrations. Total protein concentrations were similar in testicular fluid from normal and infected animals but were lower than in serum. The concentrations of individual proteins in serum did not differ substantially between infected and noninfected rabbits. In testicular fluid the concentrations of all 3 proteins, especially IgM, were greater in infected rabbits. A significantly (P < 0.02) raised testis-IgM index, together with a higher concentration of antitroponemal IgM in the infected testicular fluid than in autologous serum, suggests local synthesis of IgM antibodies.