Ultrastructural visualization of complex carbohydrates in eosinophilic leukocytes.

Complex carbohydrates in eosinophils from human, rabbit, and rat marrow were identified and localized by cytochemical and radioautographic methods. The high iron diamine-thiocarbohydrazide-silver proteinate (HID-TCH-SP), low iron diamine (LID)-TCH-SP, and periodate (PA)-TCH-SP methods were used for the localization of sulfate, sulfate and carboxyl, and vicinal glycol- containing complex carbohydrates, respectively. Golgi vesicles and small precursor granules (0.2-0.4 micrometer in diameter) demonstrated strong HID-TCH-SP staining and labeled intensely after a 10-minute pulse with 35SO4(2). Crystalloid-free or immature specific granules (0.5-0.9 micrometers in diameter) labeled heavily after a 60-minute incubation and 60-minute chase with 35SO4(2). Immature granules were graded according to their HID-TCH-SP staining. Type I granules demonstrated strong rim staining and similar or somewhat less central staining, whereas type 2 granules only demonstrated rim staining, and type 3 granules lacked staining. Fully mature crystalloid-containing granules lacked staining. LID-TCH-SP similarly stained the HID-positive sulfated material in cytoplasmic granules. PA-TCH-SP stained some Golgi vesicles and diffusely stained all precursor granules and type 1 granules. Weaker staining was observed in type 2 granules and staining was very weak or absent in type 3 and crystalloid-containing granules. In early eosinophils, tubulovesicular structures (TVS) were observed rosetting and contacting precursor and type 1 granules. These TVS contained material with strong PA-TCH-SP staining but lacked HID-TCH-SP or LID-TCH-SP-reactive acidic glycoconjugates. Flattened Golgi saccules or early eosinophils stained weakly or not at all with the PA-TCH-SP method. Small granules and TVS in late (bilobed) eosinophils displayed PA-TCH-SP reactivity and lacked HID-TCH-SP staining but differed from TVS in early eosinophils in that they were not associated as rosettes with specific granules. These results indicate that sulfated and vicinal glycol-containing complex carbohydrates are differently disturbed in immature specific granules of eosinophils and presumably become masked to staining as the granule matures.