Until recently, teleosts were considered to be devoid of parathyroids. We showed recently that the corpuscles of Stannius, that structurally have features in common with the parathyroid gland, produce a molecule resembling mammalian parathyroid hormone (PTH). We refer to this molecule as parathyrin of corpuscles of Stannius (PCS). Parathyroid secretory protein-I (SP-I) is an acidic glycoprotein, probably identical to adrenal chromogranin A, that is co-stored and co-secreted with PTH. In the present study, PCS was localized in secretory granules of fresh water eels by immunocytochemistry. In addition, several glycoproteins were identified in these granules by periodic acid-Schiff staining and/or concanavalin A lectin binding. One of the glycoproteins that was positive with periodic acid-Schiff, but not with concanavalin A, cross-reacted with antisera to bovine parathyroid secretory protein-I. When the eels were made hypercalcemic by injecting calcium or pituitary extract, there was a coincidental translocation of the PCS, immunoreactive SP-I and the glycoproteins, suggestive that these granules were undergoing exocytosis. Immunoblot analysis of saline extract of the corpuscles of Stannius confirmed that immunoreactive SP-I was present in the tissue. It exhibited a molecular mass of about 55 kDa compared to about 70-80 kDa exhibited by mammalian SP-I when analyzed by sodium dodecylsulfate-polyacrylamide gel electrophoresis.

Stannius corpuscles of the eel synthesize and secrete a mammalian parathyroid-like hormone called parathyrin of CS (PCS). PCS has been localized in the cytoplasm of all cells in the corpuscles, detection being by indirect immunofluorescence with an antiserum anti-1-84 bovine hormone (PTH). The specificity of the reaction was demonstrated by inhibition of the fluorescent staining with 1-84 bovine PTH and the active fragment 1-34 of human PTH. Variations of the cellular localization of the PCS or a complete depletion of the hormonal content, in all cells, were observed in eels made hypercalcemic by Ca overloading. The secretory activity of the two types of CS cells may be regulated by the plasma Ca2+ concentration.

In eels the parathyrin of the corpuscles of Stannius (PCS), mammalian parathyroid-like hormone, has been localized in the cytoplasm of all the cells in the corpuscles. This detection was done by indirect immunofluorescence with an antiserum anti 1-84 bovine parathormone. The specificity of the reaction was demonstrated by inhibition of the coloration obtained with the 1-84 bovine parathormone and the active fragment 1-34 of human parathormone. Variations of the cellular localization of the PCS or a complete depletion of the hormonal content were observed in eels made hypercalcaemic by calcium overloading.

Anti-idiotypic sera were obtained in Rabbits immunized with Rh antibodies (isolated from the serum sample collected in 1974 from a Blood Donor). The sera agglutinate, at high titers, red cells coated with the immunizing antibodies and, at different titers, cells coated with antibodies from serum samples taken at other periods. Inhibition of hemagglutination of anti-idiotypic sera by different samples from the same Donor was complete with the immunizing serum and partial with other samples. These results show that idiotypes or idiotypic specificities appeared or disappeared during the period studied and represent the first observation on evolution of antibody idiotypy in Man.

A microhaemagglutination test in disposable U plates has been devised for rapid, quantitative evaluation in antistreptococcal antibodies in human sera. Fresh or freeze-dried glutaraldehyde-treated sheep erythrocytes sensitized with over fifteen extracellular proteins released by group A Streptococcus pyogenes including streptolysin O, deoxyribonucleases, hyaluronatelyase, streptokinase and nicotinamide dinucleotide glycohydrolase were used. Haemagglutination and anti-streptolysin O (ASLO) titers were determined in parallel on 434 serum specimens from 123 healthy subjects ("controls") and 311 patients with a history of supposed or evident streptococcal infection. The titration of the four above-mentioned anti-enzyme antibodies has also been made on about 100 sera from both groups. Haemagglutination titre (HT) was less than 800 in control sera. By contrast it was greater than 800 up to 12 800 in patients specimens. Very good correlation was found between HT on the one hand and ASLO or anti-SK, anti-HA and anti-NADase antibodies on the other hand. HT and anti-DNase B antibodies were less correlated. Haemagglutination titres appear to rise earlier than serological titres of conventional streptococcal antibodies. The haemagglutination test described may be particularly helpful as a rapid serologic indicator of streptococcal infections and more reliable than the titration of ASLO alone, or of any one of anti-enzyme antibodies.