However, when 9G4 monoclonal antibodies (30) were used to measure sera VH4-34 immunoglobulins, we found elevated VH4-34 IgM titers in 60% (11 of 18) of the SLE subjects and, particularly, in those with high κ+λ+ B cells (Figure 6B). Here, CD40LG is linked to systemic lupus erythematosus.