Serological characterization of acidic (pI 5.5) and neutral (pI 7.1) forms of 17kD and 35kD interleukin-1.

Human interleukin-1 (IL-1) was partially purified into the acidic and neutral 17,000 dalton forms and the acidic and neutral 35,000 dalton forms. Heterologous antiserum raised against purified human IL-1 (neutral, 17,000 daltons) neutralized only the neutral 35,000 dalton and 17,000 dalton isoelectric forms. Conversely, an antiserum raised against purified porcine acidic IL-1 (21,000 daltons) neutralized only the acidic 35,000 and 17,000 dalton forms. These results confirm earlier findings that the acidic and neutral species of IL-1 are not derived from the same gene. In addition, the results suggest that each isoelectric form of the 17,000 dalton IL-1 is probably derived directly from the corresponding 35,000 dalton IL-1.