In mice, three antigen-presenting cell types [B lymphocytes, macrophages and dendritic cells (DC)] express the scavenger receptor CD36. This molecule has been implicated in many important functions, including DC maturation and antigen presentation. In murine B cells, the CD36 gene requires the Oct-2 transcription factor for its expression. We previously found that B cells from Oct-2-null mice display defects in maturation, survival and proliferation. Here we have looked for a possible role for CD36 in B cells, but found that CD36 is dispensable for all responses tested. Although loss of CD36 did not directly affect B cell function, it did modulate slightly the isotype and level of IgG produced in vivo in naive mice, and IgM in Leishmania-infected mice. We also show that in DC and macrophages, CD36 expression is independent of Oct-2. We conclude that CD36 does not play a major role in B cell function, but that CD36 may contribute indirectly to humoral immunity through cells of the innate immune system.