Complement haemolytic activity, circulating immune complexes and the morbidity of sickle cell anaemia.

The aim of this study was to find out if the number of crises and complications of sickle cell anaemia (SCA) relate to complement function, or the levels of circulating immune complexes (CIC), complement factor B (Bf), C3 and C4. In 73 steady-state HbSS patients and 50 HbAA control subjects, we determined the haemolytic activity of the alternative pathway of complement (AP50), of the classical pathway (CH50); and the serum concentrations of Bf, C3, C4 and CIC. By clinical examination of each patient and review of the medical records, we determined the number of complications of SCA which had occurred and the mean number of crises per year over a minimum period of 3 years. The mean+/-SD AP50 for the patients (14+/-2 U/ml) was significantly lower than the control value of 16+/-3 U/ml (p<0.001). AP50 had a significant inverse correlation with the number of crises (r=-0.30, p<0.02). Mean+/-SD CIC in patients (0.45+/-0.38 g/l) was significantly higher than in controls: 0.24+/-0.15 g/l (p<0.002). CIC showed a significant direct correlation with the number of complications of SCA (r=+/-0.28, p<0.02). Mean+/-SD Bf in SCA patients (0.19+/-0.09) was higher than in controls (0.17+/-0.05). The difference reached marginal statistical significance (p=0.049). SCA patients and controls had no significant differences in CH50, C3 and C4. These parameters and Bf did not correlate with either the number of crises or complications. The mechanisms underlying the correlations observed in this study are yet to be fully elucidated.

Effects of minor surgery on some aspects of platelet function.

Blood from 33 patients undergoing elective surgery for non-malignant disorders was examined before operation and on the third post-operative day. The following parameters were measured: (a) total platelet count (b) platelet volume (c) released adenine nucleotides (ATP and ADP). Whole blood platelet count (WBPC) levels increased significantly after surgery and there was significant correlations between its pre- and post-operative values (r = 0.616, p < 0.05). The relationship between mean arithmetic volume after operation (MAVA) and the whole blood platelet count after operation (WBPC A) was negative and significant (r = -0.425, p < 0.05). The results also revealed no significant differences between total and released nucleotides before and after surgery. The significant increase in whole blood platelet count post operatively may have been due to release of the splenic platelet stores. Platelets in the spleen are said to be old platelets hence the lack of a significant change in platelet volume may be due to sampling taking place three days after surgery which may not have corresponded to the time of the optimum production of young larger platelets. Also, the trauma of minor surgery may not have been strong enough to stimulate platelet production in the marrow. In the light of the above findings further investigations may be conducted in which post-operative samples would be collected at varying intervals to determine whether post-operative changes in platelet volume occur at all and when.