The distribution of CD3(+), CD4(+), CD8(+), CD19(+), CD16(+), and CD25(+) lymphocyte populations in peripheral blood as well as the plasma concentrations of interleukin-1 alpha (IL-1 alpha), and IL-2 and tumor necrosis factor alpha (TNF-alpha) were investigated in 25 children with acute rheumatic fever (ARF) at the time of admission and after 3 months and in 15 children with chronic rheumatic heart disease (CRHD) and in 15 children with streptoccocal pharyngitis (SP) in order to determine changes in lymphocyte subsets and cytokine concentrations occurring during different stages of the disease. The percentages and absolute counts of CD4(+), CD16(+), CD25(+) cells, the ratio of CD4/CD8 and plasma concentrations of IL-1 alpha and IL-2 in patients with ARF were significantly higher at admission than 3 months later. These levels were also significantly higher than in patients with CRHD, SP, or normal controls. Production of IL-2 in ARF and CRHD patients directly correlated with the percentages of CD4(+) and CD25(+) cells. According to our results, the evidences of increased cellular immune response in ARF are increased percentages CD4(+) and CD25(+) cells, CD4/CD8 ratio, and increased plasma concentrations of IL-1 alpha and IL-2. Furthermore, activation of cellular immune response was not present throughout all stages of rheumatic heart disease and also in SP. (C) 1995 Academic Press, Inc.