The physiological role of gamma-globulin

Antibacterial properties of tuftsin and its analogs

The antibacterial properties of tuftsin and its 11 analogs on 20 bacterial strains were investigated. Tuftsin showed a definite antibacterial effect at a minimal effective concentration of 62.5 micrograms/ml. All analogs were either less effective or lacked any activity. The bacteria used included some highly pathogenic organisms.

Interactions of killed Listeria monocytogenes with the mouse complement system

Incubation of mouse serum with Listeria monocytogenes involved activation of the alternative complement pathway, resulting in depletion of both classical and alternative pathway activity. The activation process gave rise to reactive (calcium- and magnesium-independent) lysis of, specifically, rabbit erythrocytes, which become resistant to this form of hemolysis by sensitization with antibodies. The possible implications of these findings for L. monocytogenes as an intracellular parasite and for rabbit erythrocytes as target cells for mouse alternative complement pathway activity are discussed.

The role of regional differences in the major histocompatibility complex in the production during pregnancy of a serum factor inhibiting macrophage migration

The response by the mother to the paternal antigens of her foetus was evaluated in the rat by the production of a serum factor which inhibits macrophage migration (serum inhibitory factor, SIF). The SIF response depended upon antigenic differences controlled by genes within the major histocompatibility complex (MHC), as demonstrated by the use of congenic strains. Differences between mother and foetus within the RT1.A region of the MHC led to SIF stimulation, whereas, differences in the RT1.B region did not. The SIF response followed the course of the pregnancy: it began at the time of implantation, reached a maximum at birth and then fell precipitously. In contrast, the SIF response to skin grafting did not correlate with differences in the MHC. Thus, the antigenic factors stimulating this maternal response to foetal antigens appear to depend upon a unique type of genetic difference, and this may be a factor in the apparent immunologic privilege enjoyed by the foetus during gestation.