A monotone Boolean circuit is a restriction of a Boolean circuit
  allowing for the use of disjunctions, conjunctions, the Boolean
  constants, and the input variables.  A monotone Boolean circuit is
  multilinear if for any AND gate the two input functions have no
  variable in common.  We show that the known lower bounds on the size
  of monotone arithmetic circuits for multivariate polynomials that
  are sums of monomials consisting of $k$ distinct variables yield the
  analogous lower bounds divided by $O(k^2)$ on the size of monotone
  multilinear Boolean circuits computing the Boolean functions
  represented by the corresponding multivariate Boolean polynomials.