A hairy cell leukemia associated antigen (HC2) has a distinct role in normal B cell differentiation

Activation antigens expressed by activated B cells, but not by resting B cells, are excellent candidate molecules for lymphokine receptors, which are expressed after B cell activation. HC2 is a previously described hairy cell leukemia associated antigen, which is not expressed by chronic lymphocytic leukemia B cells. HC2 is also found on activated B cells but not on resting B cells. Here we demonstrate that HC2 is not a B lineage restricted antigen and may be expressed by other activated cell types. Antibody to HC2 inhibits the activity of partially purified B cell growth factor in two different assays and inhibits B cell differentiation induced by pokeweed mitogen or Staphylococcus aureus Cowan stain I with interleukin-2. The HC2 antigen may therefore have a distinct role in normal B cell differentiation.