Figure 4

Secreted IP-10 by Lactococcus lactis is biologically active. Chemoattraction of L. lactis-secreted IP-10 was determined by using a Boyden chamber for chemotaxis. T lymphocytes obtained directly from human peripheral blood were stimulated with human IL-2 for 12 days. Chemotaxis assays using Boyden chambers were made with supernatants sterilized by filtration of both recombinant and wild-type Lactococcus lactis. To determine the number of chemoattracted cells, the membranes were stained with hematoxylin and the cells counted by using light microscopy at 1000 × (A). Cells in the lower chamber were incubated with specific anti-CD3+ and counted by FACS analysis (B). Supernatants of wild-type (WT) L. lactis and PBS were used as negative controls and Zymosan-activated serum (S+) as a positive control.