Abstract
The effects of silicates upon erythrocytes depend upon the degree of polymerization. Monomeric silicate does not appear to be taken up by red cells. Polymerized silicates are taken up and bound tightly. In the presence of small polymeric forms erythrocytes are lysed by complement. Larger polymers are bound to erythrocytes but do not sensitize to complement hemolysis. Larger polymers, however, are directly toxic and cause hemolysis in the absence of complement. Red cells exposed to complement-active polymers show characteristic alteration in morphology with the assumption of irregular bell shapes. Larger polymers cause the cells to become spherical before spontaneous rupture occurs. Large polymers cause erythrocyte agglutination but this is minimal or absent with small complement-active polymers. Complement-active polymers cause little or no change in osmotic fragility. Increase in mechanical fragility is a sensitive indication of the presence of larger, agglutinating polymers. The conversion of pneumococci from Gram positivity to negativity appears to be caused principally by complement-active polymers. Possible implications of polymer size and complement activity are discussed in relation to production of silicotic lesions by silica-containing ores.