Immunological memory in tuberculosis. 2. Mediators of protective immunity, delayed hypersensitivity and macrophage migration inhibition in central lymph

Leukocyte migration inhibition in bacillus Calmette-Guérin vaccinated healthy adults and in tuberculosis assayed by a rapid photoelectric procedure

A sensitive photoelectric method was used for reading migrations of human peripheral blood leukocytes from agarose microdroplets. Its rapidity enabled the use of a wide range (12 logs) of in vitro concentrations of antigen. Inhibition of migration of leukocytes (LMI) of healthy subjects having had BCG vaccination in childhood was found to occur in two zones of PPD concentrations, one high, from 10(-1) to 1000 micrograms/ml with a peak at 100 micrograms/ml, and one low, from 10(-8) to 10(-2) micrograms/ml. While three-fifths of subjects showed high zone LMI, in one-fifth it was bizonal and in another fifth observed only in the low zone. In patients with active pulmonary tuberculosis LMI, prior to all treatment, was reduced, absent, or replaced by enhanced migration, particularly in the low zone or in both zones. One and a half to four months after treatment LMI was found to be bizonal, enhanced migration having disappeared. These observations suggest the participation of two cell populations with widely different sensitivity to PPD in LMI in tuberculous and BCG vaccinated subjects and the presence of migration stimulatory lymphokine(s) during active tuberculosis.

Secondary delayed-type hypersensitivity to sheep red blood cells and minor histocompatibility antigens in mice: transfer of memory by recirculating thoracic duct lymphocytes

Secondary delayed-type hypersensitivity (DTH) in mice to sheep red blood cells (SRBC) and minor histocompatibility (H) antigens is dependent on long-lived memory T cells. In this paper we investigated whether these memory T cells recirculate. It was shown that late phase "immune' thoracic duct lymphocytes (TDL) from mice which were immunized with SRBC or non-H-2-incompatible spleen cells several weeks previously could adoptively transfer secondary DTH to these antigens. Passing the immune TDL through intermediate recipients demonstrated that these SRBC- or minor H-antigen-reactive memory T cells recirculate from blood to lymph. In contrast to mice immunized with minor H antigens, no secondary type DTH reactivity could be demonstrated in mice immunized with H-2-incompatible spleen cells. Also, after adoptive transfer of TDL from mice immunized with H-2-alloantigens, it was impossible to demonstrate an accelerated DTH reactivity.

In vitro assays of cell-mediated immunity in calves with persistent infections do not correlate with delayed skin hypersensitivity

A long-term kinetic study of the immune response of four calves experimentally infected with a M. avium strain was made using the following tests: lymphocyte stimulation (LS), leukocyte migrationinhibition (LMI), delayed skin hypersensitivity (DHS), and a radioimmunoassay (RIA) procedure for antibodies to M. avium. The cell-mediated immune (CMI) responses measured by these tests showed different courses during the infection period. The LS test showed several periods of peak values and the LMI test two peaks of responses of relatively shorter duration. At the end of the experimental period the DHS responses had decreased to insignificant levels, whereas the lymphocytes from all the calves responded in the LS test. No correlation could be detected between CMI and antibody mediated responses, and only two of the infected calves showed clear cut antibody responses measured by RIA. The results probably reflect the measurement of different aspects of the CMI response in the different test systems. The cyclical nature of the CMI measured by the LS and LMI tests may indicate the influence of regulatory mechanisms by suppressing lymphocyte sub-populations.

Enhanced elimination of Listeria monocytogenes at the site of delayed footpad reaction

The protective activity against a challenge infection with Listeria monocytogenes was investigated at the site of a delayed footpad reaction in mice immunized with viable or killed listeria. Delayed footpad reactivity was induced only in mice immunized with viable bacteria. Rapid and marked elimination of challenge bacteria was observed only at the site of reaction in mice immunized with viable bacteria but not in mice immunized with killed bacteria. Macrophage migration inhibitory activity was observed equally in both groups of mice. These results suggest that the delayed footpad reaction contributes directly to the elimination of bacteria irrespective of macrophage migration inhibitory activity.

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.