Leukocyte recruitment to inflammatory foci is generally associated with cellular activation. Recent evidence suggests that chemotactic agents can be divided into two classes, "classical chemoattractants" such as FMLP, C5a, and IL-8, which stimulate directed migration and activation events and "pure chemoattractants" such as TGF-beta 1 which influence actin polymerisation and movement but not oxidative burst and associated granular enzyme release. The studies reported here demonstrate that the murine S100 chemoattractant protein, CP-10, belongs to the "non-classical" group. Despite its potent chemotactic activity for neutrophils and monocytes/macrophages, CP-10 failed to increase [Ca2+]i in human or mouse PMN, although chemotaxis was inhibited by pertussis toxin, confirming the suggestion of a novel Ca(2+)-independent G-protein-coupled pathway for post-receptor signal transduction triggered by "pure chemoattractants." The co-ordinated up-regulation of Mac-1 and down-regulation of L-selectin induced by FMLP on human PMN in vitro was not observed with CP-10. Quantitative changes in immediate (30 s) actin polymerisation occurred with FMLP and CP-10-treated human PMN. The relative F-actin increases induced in WEHI 265 monocytoid cells by FMLP and CP-10 was optimal at 60 s and declined over 120 s. F-actin changes reflected the concentration and potencies of the agonists required to provoke chemotaxis. After 90 min, CP-10 profoundly altered cell shape and increased both cell size and F-actin within pseudopodia. These changes are typical of those mediating leukocyte deformability, and CP-10 may mediate leukocyte retention within microcapillaries and thereby contribute to the initiation of inflammation in vascular beds.

The effect of vitamin A on calcium-regulating hormones was studied in rats. A single oral dose of 30 mg retinol equivalents (RE) given to adult rats caused no change to serum biologically active parathyroid hormone (bioactive-PTH) concentrations. Bioactive-PTH secretion from rat thyroparathyroid gland complexes was not significantly altered after in vitro incubation with 1.18 X 10(-6) M retinol. Chronically intoxicated rats given 15 mg RE 3 times a week for 6 wk, showed higher osteoclast numbers and lower osteoid than controls. Serum bioactive-PTH was not detectable and serum 25-hydroxyvitamin D (25-OHD) (25.2 +/- 12.5 nmol/L) was significantly (P less than 0.03) lower than controls (43.3 +/- 3.1). In acutely intoxicated rats (60 mg RE/d for 2 d), serum bioactive-PTH levels were significantly lower (0.02 +/- 0.05 ng/ml, P less than 0.03) than in control animals (0.14 +/- 0.08). Lower doses of vitamin A, 7.5 mg RE 3 times a week for 3 wk, suppressed serum bioactive-PTH to undetectable levels but had no significant effect on serum 25-OHD. Serum calcium and 25-OHD levels were significantly lower in vitamin D-intoxicated rats given 7.5 mg RE 3 times a week (ca. 3.16 +/- 0.19 mmol/L; 25-OHD 599.7 +/- 110.6 nmol/L) than vitamin D-intoxicated controls (3.42 +/- 0.17; 789.3 +/- 17.7). These results suggest that hypervitaminosis A can alter the metabolism of calcium-regulating hormones.

The murine S100 protein CP-10 is a potent chemotactic factor for murine and human myeloid cells in vivo and in vitro. This is the first report describing regulations of the CP-10 gene by a proinflammatory stimulus, lipopolysaccharide (LPS), in cells of the monocyte/macrophage lineage. Murine monocyte/macrophage-like WEHI 265 and RAW 264.7 cells preexposed to 5 to 50 ng/mL LPS expressed significant levels of CP-10 mRNA 4 hours, and maximal at 20 hours, after a secondary LPS challenge. This was accompanied by increasing levels of cell-associated and released CP- 10 protein. In contrast, a single dose of LPS upregulated CP-10 mRNA in elicited peritoneal macrophages, whereas mRNA and protein levels decreased following LPS challenge. The state of macrophage differentiation may control responsiveness as LPS had no effect on CP- 10 basal levels in bone marrow derived macrophages. LPS-induced CP-10 expression was controlled at the transcriptional level and nuclear run- on and protein synthesis inhibition assays indicated that LPS priming and challenge of RAW cells occurred via distinct pathways. MRP14, another S100 protein generally coordinately expressed with human MRP8, was not induced by LPS under the same conditions. We propose that CP-10 may play a key role in recruitment of leukocytes into tissues in response to gram-negative bacterial infection.

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