Antibody formation in endotoxin-tolerant mice

Influence of Brucella endotoxins on the initiation of antibody-forming spleen cells in mice immunized with sheep red blood cells

Changes in the formation of antibodies to sheep red blood cells (sRBC) in the presence of Brucella extracts was studied in mice whose spleen cells were assayed by the Jerne procedure. Two strains of female mice were employed. Brucella extracts were prepared: (i) by trichloroacetic acid extraction (LPSN), (ii) by phenol extraction (LPS), and (iii) by hot acetic acid hydrolysis (Ps). B. abortus LPSN and B. melitensis LPSN or LPS, administered with sRBC, stimulated the specific response to sRBC, but only at high doses of endotoxins. B. abortus LPSN and B. melitensis LPSN suppressed nonspecific responses against horse red blood cells (hRBC), in contrast to the typical events following administration of Serratia marcescens endotoxin (or endotoxins from other ubiquitous organisms). In CD-1 mice, B. abortus Ps depressed the specific anti-sRBC response. Attempts to presensitize mice with abortus LPSN resulted in a stimulation of the response to sRBC, but pretreatment with B. melitensis LPSN had an inhibitory effect. When injected alone, Brucella endotoxins activated anti-sRBC antibody-forming cells but not anti-hRBC cells. B. abortus Ps was unable to modify the background number of anti-sRBC cells and inhibited the hRBC response. These data suggest (i) that there exists a "common antigen" between Brucella cells and sRBC and (ii) that the so-called primary response to endotoxins from ubiquitous organisms represents a secondary response to already naturally sensitized animals.

Effect of infection of mice with Friend leukemia complex viruses on background antibody-forming cell production in vitro

Friend leukemia complex (FLC), and Rowson-Parr virus (RPV) infections of donor mice depress the production of background antibody-forming cells by splenocytes cultured in the absence of specific antigenic stimulation.

Nonspecific elicitation of antibody-forming cells in the mouse spleen by bacterial lipopolysaccharide

Mechanisms of nonspecific elicitation of anti-sheep erythrocyte (SRBC) hemolytic antibody plaqueforming cells (PFC) in mouse spleens with an injection of bacterial endotoxin (lipopolysaccharide (LPS)) were studied in comparison with the genesis of naturally occurring "background" PFC in normal mouse spleens and of rapidly arising PFC in mouse spleens after immunization with SRBC. The cytokinetic pattern of anti-SRBC PFC response after an injection of LPS was quite different from that of the response elicited after immunization with SRBC. In addition, even though LPS nonspecifically elicited anti-SRBC PFC response in mice, LPS could not confer any immunological memory on mouse immunocytess for a "secondary-type" anti-SRBC PFC response to restimulation with LPS or SRBC. The administration of rabbit anti-mouse thymocyte immunoglobulin or anti-SRBC antiserum in mice markedly suppressed the PFC response after immunization with SRBC, but did not do so after stimulation with LPS. Neonatally thymectomized mice could still respond to stimulation with LPS, producing anti-SRBC PFC in their spleens. Injections of actinomycin D or cyclophosphamide into mice resulted in obvious reductions of the PFC responses elicited by either LPS or SRBC. However, injections of these immunosuppressive antisera or drugs did not affect the number of anti-SRBC PFC in normal mouse spleens. These results suggest that the genesis of anti-SRBC PFC developed under different conditions, i.e., background PFC, LPS-stimulated PFC, and antigen-stimulated PFC, are quite different from each other, and that the nonspecific elicitation of anti-SRBC PFC by LPS does not require the helper function of T lymphocytes. No obvious difference, however, was observed in the time of ontogenic maturation among these three different anti-SRBC PFC in the mouse spleens judging from when they were first manifested after birth.

Influence of Escherichia coli lipopolysaccharide on histamine-forming capacity and antibody formation in lymphoid tissues

Mice were injected intraperitoneally with 50 mug of Escherichia coli lipopolysaccharide (LPS). The spleen tissue exhibited increased histamine-forming capacity (HFC) 4 hr later. When this increased HFC was produced within 12 hr after intraperitoneal injection of sheep red blood cells (SRBC), there was an enhanced anti-SRBC antibody response in the spleen. In mice experiencing an increased spleen HFC at 36 hr after injection of SRBC, there was a significant decrease in the number of antibody-producing cells. The injection of histidine decarboxylase inhibitors simultaneously with the LPS greatly reduced the stimulation of HFC and also the adjuvant activity of the LPS.

Induced sensitization of normal laboratory animals to Brucella abortus endotoxin

A Boivin preparation of Brucella abortus, unlike common enterobacterial endotoxins, failed to depress water intake or increase numbers of hemolysin-producing spleen cells in mice, or to cause delayed inflammatory reactions in rabbit skin. Reactivity to the B. abortus endotoxin was found only in animals which were previously given the endotoxin with, but not necessarily in, complete Freund's adjuvant. Previous treatment with the endotoxin in saline or with only the adjuvant was ineffective. Sensitization appeared within 10 days and waned after 5 weeks. Passive sensitization was obtained with sensitized donor spleen cells but not with serum. Serum antibody titers did not correlate with the appearance and disappearance of sensitization.