Depressed antigen presentation function and membrane interleukin-1 activity of peritoneal macrophages after laparotomy

Although major tissue trauma produces profound depression of cell-mediated immunity, it is not known whether surgical trauma (i.e., midline laparotomy) has any adverse effect on the antigen presentation function and membrane interleukin-1 (IL-1) activity of peritoneal macrophages. To study this, C3H/HEJ (endotoxin-tolerant) mice were anesthetized. An approximately 1-inch midline abdominal incision was made, followed by abdominal closure. On days 1, 3, 5, and 7, peritoneal macrophages were harvested by means of peritoneal lavage, and antigen presentation capability was tested by incubating various numbers of peritoneal macrophages with 2 X 10(4) D10.G4.1 cells per well in the presence of conalbumin (400 micrograms/ml). The T helper cell clone (D.10.G4.1) proliferates on recognition of conalbumin in the context of Iak and also proliferates in the presence of membrane-bound IL-1 plus concanavalin A. To measure membrane IL-1 expression in peritoneal macrophages, Concanavalin A (10 micrograms/ml) was substituted for conalbumin. Cultures were incubated for 72 hours, pulsed with tritiated thymidine, and harvested. Peritoneal macrophages from laparotomized mice induced significantly less T helper cell proliferation on days 1 and 3 in the antigen presentation assay (37% and 30%, respectively; p less than 0.05) and in the membrane IL-1 assay (14% and 10%, respectively; p less than 0.05) as compared with the control. This difference was not detectable on day 5. More effective antigen presentation capability (167% of control; p less than 0.05) was seen on day 7. Thus laparotomy by itself produces marked depression of both antigen presentation function and membrane IL-1 activity of peritoneal macrophages, which may enhance susceptibility to intra-abdominal sepsis.     

Castration reduces potassium-stimulated norepinephrine release from superfused olfactory bulbs of male rats

In order to investigate the possible relationship among the olfactory bulb (OB), norepinephrine (NE) and gonadal steroids, we measured NE release from superfused anterior and posterior OB in intact and castrated male rats (Expt. I) as well as in castrated male rats implanted with either empty or testosterone filled silastic capsules (Expt. II). Both basal and potassium (K⁺ 30 mM)-stimulated release of NE was greater in posterior compared to anterior OB. All groups were responsive to the K⁺ stimuli showing increases in NE release. The degree of K⁺-stimulated release was significantly greater in intact compared to that of castrated rats. No differences in K⁺-stimulated release were observed between castrated and castrated plus testosterone-treated groups. These results demonstrate that castration of male rats significantly reduces OB noradrenergic responsiveness to K⁺ stimulation, an effect which was not restored following administration of silastic capsules containing testosterone.     

Selection of nitrogen mustard resistance in a rat tumor cell line results in loss of guanine-O6-alkyl transferase activity

Cell killing, DNA-interstrand crosslinks, and DNA-protein crosslinks were assayed in nitrogen mustard-resistant Walker 256 carcinoma (WR) cells and the parent cell line (WS) after treatment with 5-[3-(2-chloroethyl)-1-triazenyl]imidazo-4-carboxamide (MCTIC). The WR cells, which also express collateral sensitivity to chloroethylnitrosoureas, were approximately twice as sensitive to the cytotoxic effects of MCTIC as were WS cells. Following treatment with 100 microM MCTIC, there was a rapid accumulation of both DNA-interstrand and DNA-protein crosslinks in the WR cell line, which reached a maximum at 6 and 12 hr, respectively. There was considerably less crosslinking in the WS cells and both cell lines were proficient in repairing most of the crosslinks by 24 hr. Measurement of guanine-O6-alkyl transferase activity showed the enzyme to be present in WS but not in WR cells. These data indicate that the collateral sensitivity of nitrogen mustard-resistant WR cells to chloroethylating drugs is in part due to the loss of guanine-O6-alkyl transferase activity which is present in the parent line.