Effects of Homologous and Heterologous Stroma-Free Hemoglobin and Polyhemoglobin on Complement Activation, Leucocytes and Platelets

Abstract

This is a study of the effects of stroma-free hemoglobin(Hb) and polyhemoglobin on C₃ and C_3alevels and on blood cell counts. The effects of membrane stroma from red cells and endotoxins on complement activation were also investigated.

Plasma samples from rats were incubated with hemoglobin solutions or control solutions. C₃ was measured using anti-rat C₃ by nephelometric method. C_3a was measured using radioimmunoassay. C₃ and C_3a were also determined in rats receiving hemoglobin solutions, red cell stroma solutions, or a solution containing complement activators (membrane stroma and bacterial endotoxins). There were no significant differences in C₃ or C_3a levels between the plasma incubated with hemoglobin solutions and the control plasma incubated with saline (P>0.05). Compared with the saline incubated plasma, C₃ was significantly lower and C_3a significantly higher in the zymosan treated plasma (P<0.01). In hemoglobin infused rats, there was no significant difference between pre-versus post-infusion values in C₃ and C_3a. There was a significant increase in C_3a in the rats receiving stroma suspension (P<0.05) or stroma and endotoxins (P<0.02). Polyhemoglobin and stromafree hemoglobin did not cause significant changes in total leucocyte, differential, or platelet counts.

Our study suggests that purified stroma-free Hb and poly Hb do not activate complement, and that C_3a is a more sensitive parameter for monitoring complement activation than C₃. On the other hand, contaminates in hemoglobin preparations, such as membrane stroma or endotoxins, activate the complement system.

Key Words:

• stroma-free hemoglobin
• polyhemoglobin
• blood substitutes
• complement activation
• blood cells
• chemotaxins