Abnormal karyotype of human PBMCs immortalized by infection of M fermentans. Human PBMCs (K4413-Mi) from a healthy donor with a normal karyotype were infected with M fermentans incognitus strain for 5 months. The immortalized human PBMCs were subjected to the karyotyping study. Results show that more than 95% of the immortalized K4413-Mi cells had a reciprocal translocation between chromosomes 6 and 22.