Immune system, of invertebrates

Du Pasquier, L. The immune system of invertebrates and vertebrates. Comp. Biochem. Physiol. C, 129, 1, 2001. 

The following protocols can be used for the isolation and structural characterization of any natural bioactive peptides from the immune system of invertebrates. The different procedures that will be detailed below refer to the identification and primary structure determination of the Drosophila immune-induced peptides (19,20,23,27,30) and of bioactive peptides from the immune system of other Diptera (17,21,24,31). These approaches were also successfully used for the discovery of bioactive peptides from crustaceans, arachnids, and mollusks. These methods should be considered as a guideline and not as the exact procedure to follow (see Note 3). The suggested procedures will be reported following the normal order of execution, (1) induction of the immune response by an experimental infection, (2) collection of the immunocompetent cells (hemocytes), tissues (epithelia, trachea, salivary glands, etc.)... 

Because of their well-recognized physicochemical properties (relatively high hydrophobicity, cationic character, and short length) reversed-phase, size-exclusion, and cation exchange chromatographies are particularly appropriate to purify bioactive peptides from the immune system of invertebrates. The sensitivity of HPLC, MS, Edman degradation, and liquid growth inhibition assays allow one to use from narrow (e.g., 2.1-mm internal diameter) down to micro-or nano-columns. 

A relevant set of not experimentally infected individuals (control) is required for differential analysis by MALDI-TOF-MS or RP-HPLC in order to discriminate between immune-induced molecules and constitutively present substances (19). This is a prerequisite when no in vitro assays are used to select the bioactive peptides from the immune system of the model invertebrate investigated. 

Anderson, R.S. 1975. Phagocytosis by invertebrate cells in vitro Biochemical events and other characteristics compared with vertebrate phagocytic systems. In Invertebrate Immunity Mechanisms of Invertebrate Vector-Parasite Relations. Academic Press, San Francisco, CA, pp. 153-180. 

HA receptors are classified into 4 subtypes Hi, H2, H3, and H4 (Hill et al, 1997). All four HA receptor types are metabotropic receptors and belong to the superfamily of G-protein coupled receptors. Ionotropic HA receptors are found in invertebrates (Hardie, 1989 Gisselmann et al., 2002) but are absent from vertebrates (Haas Panula, 2003). Of the four HA receptors, only the Hi, H2, and H3 receptors are found in brain. The recently discovered H4 receptor is predominantly present on leukocytes and may have a critical role in the immune system (Nguyen et al., 2001 Bakker, 2004 Haas 8i Panula, 2003). 

Among recent developments in the elucidation of neuropeptide activities in non-neuronal tissues and cells, those in the immune system are receiving the greatest attention. Fascinating results obtained in invertebrates are in line with those in mammals. 

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