Mcs5a allele is associated with increased concanavalin A (conA)-induced Th1 cytokine production and proliferation. (a) Interleukin-2 (IL-2), interferon-gamma (IFNγ), or tumor necrosis factor (TNF) concentrations (in picograms per milliliter) in the media produced by cultured T cells from spleens of susceptible congenic control (susc., open bars; -DMBA n = 30, +DMBA n = 8) and Mcs5a congenic resistant (Mcs5a, filled bars; -DMBA n = 30, +DMBA n = 8) rats without or with conA stimulation. (b) IL-2, IFNγ, or TNF concentrations (in picograms per milliliter) in the media produced by cultured T cells from inguinal mammary lymph nodes (LNs) of susceptible congenic control (open bars; -DMBA n = 8, +DMBA n = 8) and Mcs5a congenic resistant (filled bars; -DMBA n = 8, +DMBA n = 8) rats without or with conA stimulation. (c) IL-4, IL-6, or IL-17 concentrations (in picograms per milliliter) in the media produced by cultured T cells from spleens of susceptible congenic control (open bars, n = 22) and Mcs5a congenic resistant (filled bars, n = 22) rats without or with conA stimulation. (d) Percentage of second- and later-generation daughter cells among CD4+, CD8+, and γδTCR+ T cells from susceptible congenic control (open bars, n = 24) and Mcs5a-resistant congenic (filled bars, n = 26) rats without or with conA stimulation. Significantly different (P < 0.05) cytokine production or proliferation between susceptible congenic control and Mcs5a-resistant congenic rat lines is indicated by an asterisk. Values are expressed as average ± standard error of the mean. DMBA, 7,12-dimethylbenz(a)anthracene; Mcs5a, mammary carcinoma susceptibility locus 5a; TCR, T-cell receptor.