The samples tested were from patients with RF elevation >200 IU/mL (21/21 HIV negative), autoantibodies (various; 21/21 HIV negative) or monoclonal gammopathy (20/21 HIV negative), or from patients positive for the following (but HIV negative): Epstein–Barr virus IgM (10/10 HIV negative), Epstein–Barr virus IgG (10/10 HIV negative), cytomegalovirus IgM (10/10 HIV negative), cytomegalovirus IgG (15/15 HIV negative), herpes simplex virus IgM (10/10 HIV negative), herpes simplex virus IgG (15/15 HIV negative), and influenza vaccine (15/15 HIV negative). The gene discussed is CD40LG; the disease is influenza.