Inability of immune cells treated with anti-thymocyte serum to confer on hamsters resistance to cutaneous infection with Treponema pertenue.

The mechanism by which hamsters acquire resistance to yaws or frambesia is poorly understood. This investigation has shown that immune lymphoid cells (spleen and lymph node) could confer on hamsters resistance to infection with Treponema pertenue. Treatment of these immune cells with a specific antithymocyte serum (ATS) inhibited the transfer of resistance. Twenty-one days after infection, recipients of immune cells treated with ATS had cutaneous lesions, in contrast to recipients of immune cells treated with normal rabbit serum. Treatment of immune cells with ATS, however, did not completely abolish resistance to treponemal infection. The weight and number of treponemes in the lymph nodes of recipients were significantly lower than those infused with normal cells treated with ATS or normal rabbit serum. The specificity of the ATS was demonstrated by its failure to inhibit functional antibody-producing cells and its high cytotoxic activity for thymocytes. These results present direct evidence that ATS-sensitive cells are involved in resistance to frambesial infection.