Figure 4

Desensitization activity is extracted by butanol. A. Butanol extraction of human HDL. One mg human HDL protein was extracted with 33% n-butanol/20 mM acetic acid as described under Methods and desensitization activity in the upper ("B") and lower ("W") phases determined. HDL represents the starting material for the butanol extraction and was included with cells at 10 μg/ml. B. Butanol extraction of a partially purified serum preparation. Active fractions (about 4 ml) from the initial C¹⁸ column were dried and extracted with 33% n-butanol/20 mM acetic acid as described under Methods and diluted 1000-fold into the cell incubation for measurement of desensitization activity in the upper ("B") and lower ("W") phases. SM represents the pooled active C¹⁸ column fractions prior to butanol extraction diluted 1000-fold into the cell incubation.