Changes in macrophage membrane proteins in relation to protein deficiency in rats

Resident and thioglycollate (TG) macrophages were isolated from rats fed 20 and 4% protein diets. These cells were cultured for 2 and 18 hr; further the membrane proteins were separated by SDSPAGE. Though basically all the samples had a similar banding pattern, the protein profile was very complex in nature. TG elicited macrophages from the protein fed group had increased contents of high molecular weight proteins compared to the resident cells from both the groups as well as TG cells from the protein deficient group. The difference increased with prolonged incubation. Polypeptides at 56.5 and 46 kd which were prominently present in the control samples, was very low in the protein deficient ones. Bands at 34, 32, 27 to 19.5 kd were reduced in the TG cells from the protein fed group. The protein deficient samples exhibited a strong band at 43 kd (presumably actin) while it was present in very small amounts in the cells from the protein fed groups. These observations indicate that the protein restriction had down regulated TG induced modulation of macrophage membrane proteins to the level of resident cells which are physiologically in a lower state of activation. These changes could reflect on their reduced functional properties.