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We have detected and partially characterized multiple lectins present in the serum of the freshwater prawn Macrobrachium rosenbergii. Since agglutination of erythrocytes (RBC) is not abolished by treatment with Vibrio cholerae neuraminidase (VCN), Macrobrachium shows an agglutination pattern different from that of other sialic acid-specific lectins such as Limulus polyphemus lectin. However, after absorption with primate and bird VCN-treated RBC, Macrobrachium serum exhibits high titers with untreated and pronase-treated RBC and no agglutination of VCN-treated RBC, suggesting a typical sialic acid specific lectin agglutination profile. Hemagglutination-inhibition tests indicate that sialic acid containing compounds are the best inhibitors for Macrobrachium lectins. Subterminal sugars and type of linkage are probably important for the lectin binding since bovine submaxillary mucin (containing mainly terminal NANA-alpha-2 6-GalNAc-) is a better inhibitor than fetuin (containing mainly terminal NANA-alpha-2 leads to 3-Gal-) and colominic acid (-NANA-alpha-2 leads to 8-NANA-) is a weak inhibitor.

Based on their carbohydrate-binding properties and their ubiquitous presence in pro- and eukaryotes, recognition functions have been hypothesized for many humoral and tissue lectins. In this review three main topics relevant to the possible biological roles and evolution of invertebrate and chordate lectins are discussed. They include the broad carbohydrate-binding spectrum of lectins from chelicerata, the distribution and specificity of cell membrane-associated lectins in mollusks and the serological and biochemical characterization of lectins from tunicates and their structural relationships with putative non-self recognition molecules from vertebrates.

A 7800 Mr peptide, apparently derived from a 70,000 Mr immunoglobulin-related protein synthesized by a marmoset T-lymphoma cell line, bears immunoglobulin-related determinants apparently contained in a disulfide-bonded loop comparable to that of the VH fragment of classical H chain. A membrane-enriched, crude particulate fraction was prepared from marmoset T-lymphoma cells, and peptides generated by papain digestion of the particulate fraction were selectively purified by affinity chromatography using IgG purified from serum of a goat immunized with the Fab fragment of a human Waldenstrom macroglobulin. The smallest of the affinity-purified peptides was particularly reactive with unfractionated goat anti Fab (G alpha Fab) serum, purified IgG from G alpha Fab serum, and with antibodies affinity purified from G alpha Fab serum using Waldenstrom macroglobulins. Partial specificity of G alpha Fab antibodies was determined by competition radioimmunoassay and radioimmunoprecipitation assays. High-performance reverse-phase liquid chromatography was used for final purification of the smallest peptide which retained its reactivity with G alpha Fab serum and affinity-purified G alpha Fab antibodies. The apparent molecular weight of the peptide, determined by gel filtration in 6 M guanidine, was estimated at 3900 in its native state but increased to 7800 after reduction and alkylation, indicating a role for a disulfide bond in the tertiary structure of the peptide. The amino acid composition of the peptide was presented, and its possible relationship to immunoglobulin-like T-cell surface proteins was discussed.

The affinity-purified major galactosyl-specific lectin (DCL-I) from the tunicate Didemnum candidum binds and induces blastogenesis in untreated and Vibrio cholerae neuraminidase (VCN)-treated murine splenocytes. However, it only binds and stimulates murine thymocytes when they have been pretreated with VCN. Binding and stimulation of VCN-treated splenocytes and thymocytes is specifically inhibited by D-galactose. Binding of lectin to splenocytes is highly increased by the VCN treatment, but the cells are stimulated to the same extent in both untreated and VCN-treated cells. This suggests that although additional DCL-I carbohydrate acceptors are uncovered by VCN treatment of the splenocytes, the ones responsible for triggering blastogenesis are already exposed on the untreated cells. On the contrary, cleavage of terminal sialic acids from the thymocyte cell surface is required to expose DCL-I carbohydrate acceptors in order to obtain a mitogenic response. Our results suggest that the distribution of cell surface galactosyl carbohydrate moieties to which DCL-I binds is different in thymocytes and splenocytes.

Protectins and agglutinins in several organs, fluids and spawn from Argentine terrestrial and fresh-water gastropod species were examined. Differences or analogies with vertebrate immunoglobulin serological behaviour are summarized. Individual or group variability and the evolutionary meaning of the reproductive system-linked and the Ca++ ion-linked protectins are discussed.

1. Eight North American species of tunicates were examined for the presence of interleukin-1 (IL-1) like activity. 2. The tunicates studied produce molecules with readily detectable lymphocyte activation factor (LAF) activity. 3. G50 column chromatography separated molecular species that were directly mitogenic for thymocytes (mol. wt greater than 50,000) from those that were comitogenic in an IL-1 assay (mol. wt 20,000). 4. Tunicate fractions with LAF activity induced increased vascular permeability in rabbit skin. 5. Tunicate LAF activity was neutralized by polyclonal anti-human IL-1 antisera. 6. These data further support the conclusion that IL-1 is an ancient and functionally conserved molecule.