Analysis of hepatitis B surface antigen expression on leucocyte subpopulations by two-color fluorescence with flow cytometry.

We have analyzed the expression of HBsAg on different subpopulations of peripheral blood cells from hepatitis B virus (HBV) infected patients using two-color immunofluorescence and flow cytometry. An average of 7.4 +/- 0.8% and 9.8 +/- 1.2% HBsAg + cells were found among cells from acute and chronic hepatitis B patients, respectively. When studied by two-color immunofluorescence, HBsAg was limited to cells expressing the B-cell restricted antigen CD19 (16.7 +/- 2.4%), whereas for the other subsets studied (CD3+, CD4+, CD8+, CD67+, CD68+) the percentage of positivity was lower than 4%. The expression of viral antigen on B cells might be relevant for a number of functional interactions between HBsAg+ B and T lymphocytes.