Haematological changes following systemic injection of purified carrageenans (kappa, lambda and iota)

Kappa, lambda and iota carrageenans were administered i.p. (125 mg/kg) to groups of Sprague-Dawley rats. Each carrageenan (but especially kappa and lambda) caused thrombocytopenia and red-cell damage, particularly burring, within 2 days. This was followed by rebound thrombocytosis and persistent anaemia, accompanied by a reticulocytosis. A 2-fold increase in fibrinogen was observed at 24 or 48 h. All groups showed a leucopenia at 1 h, then a progressive leucocytosis, maximal at 48 h (kappa and lambda) or Day 7 (iota). Between 1 and 24 h there was a significant lymphopenia, followed by lymphocytosis (kappa and lambda) including Turk cells and pronounced neutrophilia in all groups. Monocytosis occurred in response to each carrageenan on Days 2-4 (kappa) or Day 7 (lambda and iota). Injection of kappa carrageenan was characterized by the presence (up to Day 7) of carrageenan-positive material, in the form of floccules, within the peripheral blood, and by Day 7 the appearance of histiocyte-type macrophages which exhibited haemo-phagocytosis. In the lambda group, carrageenan-positive granules were observed in the cytoplasm of mononuclear cells throughout the experimental period. No intracellular carrageenan was demonstrable in peripheral blood in the iota group or within neutrophils of any of the injected animals. Overall marrow cellularity was not altered by carrageenan, but small numbers of kappa- and lambda-containing macrophages were identified. Splenomegaly was consistently observed and in histological section carrageenan-positive macrophages were detected in the red pulp, particularly in the lambda group.