From the contents: In seven comprehensive reviews, the following topics are covered: Interactions between cells and integration of cell activities: A functional immune system after antigenic challenge: Comparative biology of the x2-macroglobulin-based immune system.- Evidence for invertebrate inflammatory cytokines.- Lectins.- Models of natural and induced molecules in invertebrates.- Histocompatibility reactions in invertebrates.- The environment: The consequences of connections and missed signals: Parasite-invertebrate host immune interactions.- Environmental pollution and toxicity in invertebrates.- The invertebrate neuroendocrine and immune systems.