Coexpression of CD4 and CD8 on mitogen-activated peripheral blood T cells from children with asthma: possible involvement of interleukin 4.

Mononuclear cells were isolated from the peripheral blood of 28 asthmatic and 18 healthy children aged 3 to 16 years. The cells were stimulated with phytohemagglutinin for 96 hours. Activated cells were detected microscopically by MTT staining. Expression of cell surface antigens was detected by indirect immune fluorescence using CD4-specific and CD8-specific monoclonal antibodies. Results indicate an enhanced expression of CD8 on mitogen-activated T cells from asthmatic children compared with cells from healthy controls (median 43% versus 27%). Further experiments revealed that CD8 is coexpressed with CD4 on activated lymphocytes. Coexpression is significantly enhanced with lymphocytes from asthmatic patients compared with normal controls. In addition, interleukin 4 is able to enhance this coexpression with lymphocytes from healthy but not asthmatic children suggesting an in vivo preactivation of lymphocytes from asthmatic patients with interleukin 4.