Mycoplasma-dependent activation of normal lymphocytes: mitogenic potential of mycoplasmas for mouse lymphocytes

Nonviable preparations of a wide variety of glucose-utilizing mycoplasma species, including Acholeplasma laidlawii and Spiroplasma citri, were found to be mitogenic for mouse lymphocytes. Particularly strong reactions were obtained with Mycoplasma synoviae, M. gallisepticum, M. pneumoniae, S. citri, and a strain of M. fermentans that was previously isolated from a leukemic patient. Nonviable preparations of arginine-utilizing mycoplasmas inhibited the uptake of [3H]thymidine by lymphocytes, but this effect could be reversed by heat treatment or arginine supplementation, and a stimulatory effect was then observed. Viable M. arthritidis was also found to have a mitogenic effect, as detected by an increased uptake of [3H]thymidine by normal lymphocytes and by autoradiographic techniques in which an increase in the numbers of transformed cells was seen. These observations provide the potential for enhanced immunological responsiveness or lymphokine-mediated inflammation in mycoplasma-infected hosts.