Isolation and in vitro characterisation of prohaemocytes from the spider crab, <i>Hyas araneus</i> (L.)

A population of small, undifferentiated haemocytes from the spider crab, H. araneus were identified and enriched from the circulation using a two-step density gradient separation procedure. Typically, these cells are spherical, ca 8-12 μm diameter, with a high nucleus:cytoplasm ratio, are non-adherent and non-phagocytic. Their number in the circulation is increased by experimental haemocytopenia in a manner consistent with a left shift phenomenon. However, by 96 h, their number returns to pre-treatment levels. Approximately 46 % of these small cells are BrdU-positive in vitro. LPS exposure at a concentration of 0.33 μg mL-1 produces a significant rise in the proportion of positive cells to 65 %, although higher LPS concentrations at &gt;3 μg mL-1 have no such effect. This proliferative ability coupled with their close morphological resemblance to immature haemocytes reported from the haemopoietic tissue of other decapod species leads us to conclude that these cells are true prohaemocytes