The Immunological Basis of Acquired Cellular Resistance

Abstract

Infection with certain organisms is often found to produce a high degree of resistance towards other, unrelated organisms (1). The phenomenon is conspicuous whenever the immunising infection is caused b y a facultafive intracellular parasite (2). The latter provokes an immune response with three peculiarities: a consistent association with delayed-type hypersensitivity, a form of acquired resistance that cannot be passively transferred with serum, and a reported change in the antibacterial activity of the host's macrophages.I t is usual to dismiss the cross-resistance caused b y such organisms as an example of "non-specific immunity," and to ignore the possible immunological significance of the phenomenon. I t was decided to reinvestigate the problem in the hope of arriving at a better understanding of the immunological processes involved in this type of acquired antibacterial resistance. In this report the specificity of both the induction and the expression of acquired resistance has been studied in mice immunised with three facultative intracellular parasites;Listeria monocytogenes, Brucella abortus, and Mycobacterium tuberculosis. Materials and MethodsMice.--The mice used were of an outbred strain (3). Animals of the one sex and of comparable age (7 to 8 weeks) were used in individual experiments.Organisms.PThe strain of L. monocytogenes (NCTC 7973, serotype I) was sustained at high virulence by continuous passage in normal mice. The attenuated vaccine strain of Br. abort, us (strain 19) was obtained from the Commonwealth Serum Laboratories (Victoria). Both organisms were grown in brain-heart infusion broth (BI-II, Difco Laboratories, Inc., Detroit). Suspensions of bacteria were prepared from 16-hour and 3-day cultures of L. monocytogenes and Br. abortus, respectively. The organisms were washed once and resuspended in Hanks' solution containing 0.1 per cent bovine serum albumin (fraction V, Armour). The LDs0 for L. monocy-/ogenes was 1.0 X 105 by intravenous injection; that for Br. abor/us (strain 19) was not determined.Bacterial Enumeration in the Spleen.--The method of determining the viable bacterial count in the spleen was previously described (3). Colony counts were made after 24 hours and 4 days for/./stcr/a and Brucdla cultures respectively.Dete~$ion of Listcria-Resistant Macrophages.--The method used for preparing and parasifis-

Properties of Antibodies Cytophilic for Macrophages

“…Data has been presented showing that macrophages from sensitized animals react characteristically to specific antigen. Mackaness has reported that macrophages from immunized mice proliferate in vivo when in contact with the sensitizing bacterial antigens and evolve into cells better able to suppress nonspecifically the growth of ingested microorganisms (31). Peritoneal macrophages from sensitized guinea pigs clump and adhere to peritoneal surfaces in vivo when antigen is injected (32).…”

M-1/M-2 Macrophages and the Th1/Th2 Paradigm

“…Th1 macrophages preferentially produce NO from arginine; Th2 macrophages produce ornithine. PEC from Th1 or Th2 strains of mice were cultured for 48 h, and supernatants were measured for NO 2 Ϫ and amino acids. RPMI 1640 contains 1100 M arginine.…”

“…M acrophages are essential for host defense (1)(2)(3)(4)(5)(6)(7). In primitive organisms, macrophages are the host defense, in that they are responsible for everything from recognition to engulfment to destruction of threats (8).…”

The liaison between apoptotic cells and macrophages – the end programs the beginning

“…Since Mackaness and colleagues first described classically activated macrophages as major immune effector cells (Mackaness, 1964), considerable knowledge has been gained concerning distinct macrophage populations, with diverse functional roles. The remarkable plasticity of macrophage responses was classified towards two extremes: M1 and M2 macrophages.…”