Mitogenic responses of frog lymphocytes to crude and purified preparations of bacterial lipopolysaccharide (LPS)

We have compared $\text{in}$$\text{vitro}$ mitogenic responses of frog ($\text{Xenopus}$$\text{laevis}$ and $\text{Rana}$$\text{pipiens}$) lymphocytes to various preparations of lipopolysaccharide (LPS). Commercial LPS prepared from $\text{E}$. $\text{coli}$ (phenol extraction) and from $\text{S}$. $\text{abortus-equi}$ (phenol and TCA extraction procedures) was mitogenic for frog lymphocytes. After reextraction of these LPS preparations with phenol-water, the remaining LPS was either considerably less mitogenic or not mitogenic. Purified $\text{E}$. $\text{coli}$ 055:B5 LPS, prepared by phenol water extraction, enzyme treatment and column chromatography, was not mitogenic. Frog cells proliferated poorly or not at all with all concentrations of reextracted or purified LPS tested (0.5–400 ug/ml) and at all culture periods examined (days 1–7). All LPS preparations used were mitogenic for CAF₁ mouse lymphocytes, whereas reextracted and purified LPS preparations were not mitogenic for lymphocytes from C3H/HeJ cells. $\text{Xenopus}$ were also not susceptible to toxicity induced by parenterally administered LPS in concentrations which killed CAF₁ mice.