ABSTRACT
PURPOSE: The CD5 molecules of mice (Ly-1) and humans (T1) are pan-T cell antigens and are also found on a minor subpopulation of B cells. Cl)5+ B cells constitute a large fraction of the B cells early in development and in neonate. There are many reports about the production and mRNA expression of CD5+ B cells and in this study CD5 mRNA expression by peripheral blood mononuclear cell (PBMC) was examined in neonate and compared with those in normal children and childrens of acute febrile diseases. METHODS: Ten normal neonate(mean age, 1.2 days), ten children of acute febrile disease (mean age, 8.5 months) and ten nomal children (mean age 9 months) were studied. One mililiter of venous blood was drawn and immunophenotypes were determined using FACS (fluorescent activated cell sortor) with FITC-conjugated anti-CD5 and PE-conjugated anti-CD 19. PBMC was separated and CD5 mRNA expression was examined in these groups. RESULTS: 1) From the analysis using FACS, there was no significant difference for the CD5+ 1' cell fractions in white blood cells among neonates(78.52+13.98 %), acute febrile infectious disease controls (l0.86 + 5.56 %) and normal controls (73.53 + 4.62 %) (p>0.05). 2) The fractions of CD5+ H cell in B cells were markedly high in neonate (65.18+ 13.67 %) as compared to that in children of acute febrile disease controls (27.14+5.96 %) and normal controls (20.04+5.92 %) (p<0.001). 3) CD5 mRNA expression was detected only in neonate and not in children of acute febrile disease controls or normal controls. CONCLUSIONS: Neonate has a large fraction of CD5+ B cells in total H cells as compared to that of children of acute febrile diseases or normal controls. PHMC of neonate normally expressed CD5 mRNA but that of acute febrile group or normal control group did not. Further study about the roles and meanings of CD5 mRNA expression may be needed.