ONTOGENY OF MACROPHAGE RESISTANCE TO MOUSE HEPATITIS IN VIVO AND IN VITRO

Gallily, Ruth; Warwick, Anne; Bang, Frederik B.

Mice.--The C3H strain was originally obtained from Dr. H. B. Andervont of the National Cancer Institute as a strain free of the milk agent. It has been inbred in this laboratory for 69 generations. The PRI strain of mice was obtained from Dr. John Nelson in 1954 and has maintained, as an inbred strain, for 28 generations. Macrophages from Liver.--Smail pieces of fiver, about 1 mm square, from 1-to 8-day-old mice, were placed on a layer of reconstituted rat tail collagen (3, 4) , in roller tubes, in the roller drum. Chang's medium was used to culture the fiver macrophages. This medium (5) contains 90% inactivated horse serum, 2% beef embryo extract, and 8% Hanks' BSS. The tubes were kept for 25-30 days. The media were changed, in most of the experiments, 7 days after virus was added, and every 4-6 days thereafter. In a study to be reported elsewhere, Huang (J. H. Huang, unpublished data) has found that certain horse sera contain inhibitors for MHV. The results reported are limited to sera from individual horses known to be free of inhibitor. are summarized in Table I . The data in the table indicate that newborn C~I mice are highly susceptible to the virus and that the resistance of the C~-I mouse to MHV increases with its age. 14-day-old mice were, as previously indicated for weanllngs (2) , fully resistant to a standard inoculation of the virus (0.1 ml of a 10 -~ dilution of the stock virus suspension). The survival time of infant C~I-I mice, infected with different dilutions of MHV(PRI), was 6.5-8.5 days and it did not vary significantly either with the age of the animals or with the dilution of the virus (Table II)