Maturational changes in CD4+ cell subsets and lymphokine production in BXSB mice

CD4+ cells are thought to play a significant role in the development of lupus-like disease in a variety of autoimmune disease-prone mouse strains. In one such strain, BXSB/MpJScR, male mice develop severe lupus-like symptoms early in life but females do not. In this study, splenic CD4+ cells from male and female BXSB mice were evaluated for age-related changes in: 1) membrane expression of CD4+ cell subset markers (1, 2, and 4 mo) and activation Ags (4 mo) and 2) the capacity to proliferate and produce cytokines (4 mo) in response to polyclonal stimuli. CD4+ cells from females of all age groups and from younger males were predominantly CD44lo, CD45RBhi, MEL-14hi, and 3G11hi (phenotypes associated with naive T cells). In contrast, 4-mo-old males were predominantly CD44hi, CD45RBlo, MEL-14lo, and 3G11lo (phenotypes associated with activated/memory T cells). Furthermore, an increased constitutive expression of the activation Ags RL388, IL-2R, and TfR was observed in CD4+ cells of 4-mo-old male BXSB mice in comparison with age-matched females. In 3-day cultures, purified CD4+ cells from 4-mo-old males proliferated significantly less than cells from age-matched females in response to plate-bound anti-CD3 epsilon (2C11i). The reduced proliferation was restored in large part by PMA and ionomycin. CD4+ cells from older males generally produced increased amounts of IFN-gamma and IL-4 and significantly less IL-2 than age-matched females in response to either stimulus (IL-2 mRNA was also decreased in response to 2C11i). Taken together, these studies suggest that profound phenotypic and functional changes occur with age in the CD4+ cells of male BXSB mice that are indicative of an activated state.