Polymorphonuclear neutrophil granulocyte chemotactic hyperresponsiveness in a case of canine acromegaly

Characterization of the priming effect by pituitary canine growth hormone on canine polymorphonuclear neutrophil granulocyte function

In this report, we demonstrate that canine growth hormone (cGH) is capable of priming canine polymorphonuclear neutrophil granulocytes (PMN) in a manner resembling that of human PMN. The cGH influences important functions that are involved in the process of recruitment of PMN, i.e., shape change, chemotaxis, CD11b/CD18 expression, adhesion, and subsequent transendothelial migration. Also, intracellular O(2)(-) production was evaluated. We investigated the priming effect by incubating PMN with purified pituitary cGH at various concentrations (10 to 800 microg/liter). The capacity for shape change was significantly (P < 0.05) enhanced, whereas the chemotactic response under agarose was significantly (P < 0.05) reduced. The chemotactic migration in Boyden chambers (10-microm-thick polycarbonate filter; lower surface count technique) was significantly (P < 0.05) enhanced, presumably due to cGH-induced hyperadhesiveness to the lower surface of the filters. The adhesion in albumin-coated microtiter plates and adherence to canine pulmonary fibroblasts were significantly (P < 0.05) increased, and the increased adhesion resulted in a significant (P < 0.01) increase in transendothelial migration using canine jugular vein endothelial cells. The increase in adhesion was associated with a significant increase in CD11b/CD18 expression. Furthermore, intracellular O(2)(-) production was significantly enhanced in response to both phorbol myristate acetate (P < 0.01) and opsonized zymosan (P < 0.05). In the absence of a PMN-stimulating agent, cGH did not influence the effector functions investigated except for an increased expression of CD11b/CD18.

Determination of insulin-like growth factor 1 in dogs using a commercially available immunoradiometric assay1)

The objective of the present study was to characterize a commercially available immunoradiometric assay (IRMA) intended for the determination of human insulin-like growth factor 1 (IGF-1) when used to determine IGF-1 in canine plasma samples. The assay was evaluated by assessment of the precision, accuracy, and detection limit, and by comparing the IGF-1 values observed in healthy dogs and in dogs with acromegaly and hereditary pituitary dwarfism to values reported in the literature. Since extraction of IGF-1 from its binding proteins is essential for reliable test results, the efficiency of the extraction method used in the assay was also examined. The main conclusions can be summarized as follows: The commercially available IRMA method offers a precise determination of the IGF-1 concentration in canine plasma samples with IGF-1 values directly comparable to those obtained by others. The assay accuracy was confirmed for normal dogs by parallelity between IGF-1 concentrations and plasma dilutions, whereas plasma from acromegalic dogs could not fullful parallelity. The detection limit was below the IGF-1 concentrations observed in dogs with hereditary pituitary dwarfism. In plasma samples with low or normal IGF-1 levels, the assay's extraction efficiency was comparable to that found using other extraction methods. In samples with IGF-1 concentrations above usual physiological levels, the extraction efficiency decreased unexplainably. However, this decrease in extraction efficiency seems to be of only minor importance when the measurements are used in the diagnosis of canine acromegaly.