Cell-mediated immune-type response of the American cockroach.

Cell-mediated immunity in the American cockroach, Periplaneta americana, was measured by counting nuclei in a transect through the mass of host hemocytes reacting against transplanted xenograft or autograft integument. Responses to xenografts (Leucophaea maderae) were significantly higher than control responses to autograft integument. Responses to Leucophaea xenografts increased with longer durations of xenograft exposure to hosts for up to eight days, then decreased by day sixteen. Responses to cockroach species from a phylogenetically graded series of donors were stronger and correlated with increasing phylogenetic distance between various donors and hosts (Periplaneta americana).