CD4 and escherichia coli infection: In pregnant Balb/c [H-2d] mice treated with 4 ppm of arsenic trioxide from the time of conception until parturition, the offspring exhibited low levels of IgG2a, reduced allogeneic stimulation of CD4+ T cells, reduced number of splenic CD4+ and CD8+ lymphocytes, and a higher susceptibility to Escherichia coli infection (182).