Cellular immune responses of BALB/c mice infected with 80 or 160 L3 of Litomosoides sigmodontis were studied over a period of 200 days postinfection (p.i.) by stimulating spleen cells with specific microfilariae and adult antigens and Concanavalin A (Con A). Effects were determined as the level of transcription of cytokine genes [interleukin (IL)-2, interferon (IFN)-gamma, IL-4, IL-5, IL-10, IL-13] employing a semiquantitative reverse transcriptase-polymerase chain reaction technique. Con A stimulation resulted in generally enhanced transcription levels in infected animals. Exposure to filarial antigens stimulated T cells of infected animals dependent on time p.i. There was a general strong response in the early prepatency (24 days p.i.), a temporary almost complete downregulation of cytokine gene transcription except IL-10 towards the end of prepatency (45 days p.i.), and subsequently strong reactions particularly concerning IFN-gamma and IL-13 during patency and postpatency. The dose of infection as well as the mode of antigenic stimulation had generally only small effects on the cytokine gene transcription: following the same type of kinetics, infection with 160 L3 as well as the use of microfilarial antigen generally induced lower levels of cytokine gene transcription compared with infection with 80 L3 and stimulation with female antigen, respectively.