Delayed hypersensitivity during casein-induced murine amyloidosis.

Cellular immunity has been studied in mice at various times during the induction of amyloidosis following multiple injections of casein. The assay system used was one which measured delayed hypersensitivity (DH) in vivo, by injecting antigen into the left ear lobe of sensitized mice, followed by the intravenous administration of ¹²⁵I-deoxyuridine (¹²⁵I-UdR). The ears were then cut off and the $\text{L}\text{R}$¹²⁵I-UdR ratio provided a measure of DH. It was found that DH to casein appeared in pre-amyloidotic mice, remained through the stages of mild and moderate amyloidosis and disappeared in severely amyloidotic mice. DH to fowl IgG disappeared after three injections of casein and remained absent at all times thereafter, likely due to antigenic competition. In contrast, DH to DNFB persisted at all times, even in the face of severe amyloidosis. These results have been interpreted to indicate that, using this assay, DH is normal during casein-induced murine amyloidosis.     

Lymphocyte transformation induced by autologous cells.

Human peripheral blood T lymphocytes are stimulated to proliferate when cultured with autologous B-lymphoblastoid cell lines, autologous mitogen-induced lymphoblasts, or autologous non-T blood lymphocytes. This reaction, the autologous mixed lymphocyte reaction, has attributes of an immune response possessing both memory and specificity. The capacity to stimulate autologous T lymphocyte proliferation depends on the lineage of the lymphoid cell and not on its establishment in continuous culture or carriage of the EB viral genome. The determinant on non-T lymphocytes which stimulates the autologous mixed lymphocyte reaction appears to be an Ia determinant. Thus, allogeneic graft rejection and the allogenic mixed lymphocyte reaction are very likely extensions of an immune response expressed within the host.     

Lymphocyte apoptosis in murine Pneumocystis pneumonia

Background

Apoptosis of lymphocytes is important in the termination of an immune response to infection but has also been shown to have detrimental effects in animal models of systemic infection and sepsis. We sought to characterize lymphocyte apoptosis in an animal model of pneumonia due to Pneumocystis murina, an infection localized to the lungs.

Methods

Control mice and mice depleted of CD4+ lymphocytes were inoculated with Pneumocystis. Apoptosis of lung and spleen lymphocytes was assayed by flow cytometry and PCR assay of apoptotic proteins.

Results

In control mice, apoptosis of lung lymphocytes was maximal just after the infection was cleared from lung tissue and then declined. However, in CD4-depleted mice, apoptosis was also upregulated in recruited lymphocytes in spite of progressive infection. In splenic lymphocytes, apoptosis was observed early at 1 week after inoculation and then declined. Apoptosis of lung lymphocytes in control mice was associated with a decrease in mRNA for Bcl-2 and an increase in mRNA for Bim. In CD4-depleted mice, lavaged CD8+ cells did change intracellular Bcl-2 but showed increased mRNA for Bim.

Conclusion

Apoptosis of both pulmonary and extrapulmonary lymphocytes is part of the normal host response to Pneumocystis but is also triggered in CD4-deficient animals with progressive infection. In normal mice apoptosis of pulmonary lymphocytes may serve to terminate the immune response in lung tissue. Apoptosis of lung lymphocytes takes place via both the intrinsic and extrinsic apoptotic pathways and is associated with changes in both pro- and anti-apoptotic proteins.     

Lymphocyte transformation studies in drug hypersensitivity

In a group of patients with clinically diagnosed drug hypersensitivity the in vitro lymphocyte response to the suspected drug was assessed by the lymphocyte transformation test. The test gave positive results in all 15 patients with penicillin-induced immediate or accelerated allergic reactions and positive immediate skin-test reactivity to the major or the minor antigenic determinant of penicillin, or both, but in only 3 of the 12 patients with delayed-onset maculopapular rashes induced by penicillin, despite positive immediate reactivity to the skin-test reagents.Lymphocyte stimulation greater than five times the control level was demonstrated for five patients with penicillin-induced erythroderma, Stevens-Johnson syndrome or a serum-sickness-like illness, or with methicillin-induced interstitial nephritis, all of whom had negative reactions to the appropriate skin-test reagents. A low level of stimulation was seen in eight other skin-test-negative patients with possible allergic reactions induced by penicillins. However, in all subjects tested the stimulation was significantly greater than the mean for control subjects.For 9 of 11 patients with isoniazid-induced hepatitis or maculopapular rashes, but for only 8 of 31 patients with eruptions induced by a variety of drugs other than penicillins and isoniazid, significant stimulation occurred in the lymphocyte transformation test.It is concluded that the lymphocyte transformation test is useful in the detection of hypersensitivity to the penicillins (although in IgE-mediated reactions skin testing is clearly preferable) and isoniazid but is of limited value in the demonstration of hypersensitivity to other drugs.     

Lymphocyte transformation and transmembrane potential depressors

Potassium and rubidium at high concentrations, as well as valinomycin, gramicidin, and ouabain, inhibit the PHA-induced synthesis of DNA. They act primarily at an early step in the G 1 period. All these inhibitors have in common a tendency to depress the transmembrane potential suggesting a relationship between the potential and lymphocyte transformation.