The modification of phagocytosis by different K1 capsule preparations of Escherichia coli

The influence of two different types of Escherichia coli K1 capsule preparation on the phagosytosis of an E. coli laboratory strain (LN 28) by polymorphnuclear leucocytes (PMNL) is described. Capsule material of E. coli 0.18 and 0.83 was prepared a) from the culture supernatant and b) from a bacterial pellet fraction. When capsule material from the pellet was added to opsonin, before mixing the laboratory strain with the PMNL, it decreased the rate of phagocytosis, compared with untreated opsonin. The preparation from the supernatant of capsule showed no alteration of phagocytosic rate or capacity. These results are explained by the different chemical compositions of the preparations.