Chapter 15, Problem 18RA

Which of these statements about gamma interferon is false?

$\begin{array}{l}\text{a}\text{. It is a polypeptide autocrine regulator}\text{.}\hfill \\ \text{b}\text{. It can be produced in response to viral infections}\text{.}\hfill \\ \text{c}\text{. Tt stimulates the immune system to attack infected cells and tumors}\text{.}\hfill \\ \text{d}\text{. It is produced by almost all cells in the body}\text{.}\hfill \end{array}$