Immune conservation: a possible consequence of the mechanism of interferon-induced antibody suppression

The effect of interferon preparations on the development of single clones of antibody-forming cells generated against sheep red blood cells in mouse spleen cell cultures has been studied. It was found that the presence of interferon had no effect on either the number or the size of clones which developed early in the in vitro antibody response. At the peak of the response (day 3), a decrease in the number but not in the size of clones was observed in interferon-treated compared to control cultures, while by day 4 both the size and number of clones were significantly decreased. These findings indicate that interferon appears to affect only nonactivated B cell precursors by preventing them from becoming activated and commencing clonal expansion. Early responding precursors, which are in cell cycle, presumably having been previously activated in vivo, are refractory to interferon-induced suppression in vitro. The way in which this immunosuppressive activity of interferon might be of great advantage to an animal as a means of "immune conservation" during viral infections is discussed.