Defective responsiveness of CD5⁺ B1 cells to lipopolysaccharide in cytokine production

Previously, we found that mouse TH2.52 cells possess the characteristic of CD5⁺ B1 cells and proliferate in response to lipopolysaccharide (LPS). The effect of LPS on cytokine production by TH2.52 B1 cells was studied. TH2.52 cells constitutively produced a small amount of tumor necrosis factor (TNF)-α and interleukin (IL)-6, and TNF-α and IL-6 production was markedly enhanced by LPS stimulation. Although interferon (IFN)-γ caused the production of various cytokines, such as IL-2, IL-4, IL-6 and TNF-α in TH2.52 cells, LPS did not cause the production of such cytokines. LPS did not induce IFN-β production in TH2.52 cells and TH2.52 cells lacked the expression of several molecules participating in the MyD88-independent pathway in LPS signaling. Defective responsiveness of TH2.52 B1 cells to LPS in cytokine production might be responsible for the failure of IFN-β production due to the lack of molecules participating in the MyD88-independent pathway.