The distribution of perforin in normal tissues

Granzyme B and perforin: constitutive expression in human polymorphonuclear neutrophils

Polymorphonuclear neutrophils (PMNs) produce an abundance of bactericidal and cytotoxic molecules consistent with their role as first-line defense against bacterial infection. PMNs, however, also cause efficient cellular cytotoxicity when targeted through Fc receptors to appropriate antibody-coated target cells. Although this so-called antibody-dependent cellular cytotoxicity (ADCC) was described many years ago, the mechanism of killing is still elusive. We now have found that PMNs contain perforin and granzyme B, the 2 molecules known as the cytotoxic entity of natural killer cells and of cytotoxic T lymphocytes as well. Lysates of PMNs were lytic for chicken erythrocytes in a time-, temperature-, and Ca2+-dependent manner. Moreover, apoptosis of Jurkat cells was induced, consistent with the observation that the PMN lysates contain enzymatically active granzyme B. Taken together, our data provide evidence for the presence of perforin and granzyme B within the cytotoxic arsenal of PMNs. (Blood. 2004;103:1099-1104)

Lymphokine-activated killer cells induced in vivo in mice showing IL-2 toxicity have cytoplasmic granules containing perforin and its hemolytic activity

Cytoplasmic granules of LAK cells isolated from mice showing side effects of recombinant human IL-2 (rhIL-2) display BLT-serine esterase activity and calcium-dependent hemolytic activity and seem to be involved in the mechanisms of LAK cell-mediated rhIL-2 toxicity. In this report, the hemolytically active substance was partially purified from the LAK granules and shown to be mouse perforin. Mice were implanted with miniosmotic pumps filled with a dose of rhIL-2 that induced known toxicity. The LAK granules were isolated from LAK cell-rich subcutaneous tissue around the infusion sites. The hemolytically active substance in the granule preparation was solubilized by 2 M NaCl and passed through a butyl Sepharose column and then a DEAE Toyopearl column. In immunoblotting, the hemolytically active fractions reacted with an anti-mouse perforin mAb and the reaction depended on the activity. The molecular sizes of the perforin-positive bands were 66 kDa and 51 kDa under reducing and nonreducing conditions, respectively. These results confirmed the existence of mouse perforin and its hemolytic activity in the LAK granules of rhIL-2-treated mice, as has been shown for granules of cytotoxic T or NK cell clones in vitro.

Perforin-expressing lymphocytes in peripheral blood and decidua of human first-trimester pathological pregnancies

PROBLEM

We have shown previously that the decidua of first-trimester human pregnancy is heavily infiltrated with perforin-positive cells. The aim was to detect expression of perforin in both decidual lymphocytes (DL) and peripheral blood lymphocytes (PBL) in the first trimester of pathological pregnancies: Anembryonic pregnancy and missed abortion.

METHOD

Decidual tissue from a normal pregnancy group and from pathological pregnancies was obtained by vaginal curettage. Perforin (an intracellular antigen) and the cell surface antigens CD3, CD4, CD8, CD16, CD56, CD11c, and CD45RA were quantified simultaneously by flow cytometric analysis.

RESULTS

In the missed abortion group, we found: 1) a relative decrease in the frequency of both CD4+P+ cells and CD56+P+ cells as well as the mean fluorescence intensity for perforin; 2) a relative increase of CD16+P+ PBL cells; and 3) a relative increase of CD4+ cells in PBL compared with anembryonic pregnancy and normal pregnancy. There was also a significant relative decrease in the proportion of CD4+ and CD8+ cells among perforin-positive PBL in both anembryonic pregnancy and missed abortion.

CONCLUSION

Our results show that significant decreases in the prevalence of perforin-positive lymphoid cells, their subpopulations, and mean fluorescence intensity for perforin are associated with pregnancy failure.

Distribution of perforin-containing cells in normal and pregnant mice

Cytotoxic T lymphocytes (CTL) and natural killer (NK) cells elaborate a cytolytic protein named perforin or cytolysin. It was widely held that, in vivo, high quantities of perforin are not present in resting lymphocytes and are usually produced only by activated lymphocytes found under pathological conditions. Until now, only one tissue was known to synthesize abundant quantities of perforin under nonpathological conditions, the uterus during pregnancy. To investigate the possibility that perforin might also be synthesized by other tissues, several tissues besides the uterus from pregnant and normal mice were tested by immunofluorescence and immunoperoxidase for the presence of perforin. The tissues studied were the ears, brain, nasal epithelium, tongue, salivary gland, larynx, thymus, stomach, liver, spleen, small intestine, and lymph nodes; two cell populations with different sizes and levels of perforin expression were found. Large cells, displaying the NK cell phenotype and expressing high levels of perforin, were detected not only in the uterus but also in the salivary gland and lungs of pregnant mice. Small cells, expressing low levels of perforin, were detected mainly in the stomach and small intestine, and they were expressed in both pregnant and normal mice. Taken together, these results imply that perforin-containing cells exist in vivo under nonpathological conditions, and that the immune system is endowed with heretofore unknown mechanisms for stimulating the activation of NK cells in a limited number of tissues during pregnancy.

Perforin-expressing granulated metrial gland cells in murine deciduoma

It has previously been shown that granulated metrial gland (GMG) cells of the pregnant uterus express abundant quantities of the lymphocyte pore-forming protein, perforin. No perforin was present before implantation of the embryo, but large numbers of perforin-producing GMG cells were observed after implantation, which coincides with decidualization of the uterus. The possible source of the activation factors responsible for perforin gene induction in GMG cells was studied here with the pseudopregnancy model, in which cervical stimulation of mice during estrus leads to a series of hormonal changes resembling those seen in pregnancy, but in the absence of an embryo. Subsequent stimulation of the uterus of pseudopregnant mice with oil causes the stimulated portion of the endometrium to differentiate into decidual tissue. Perforin-containing GMG cells were in fact present in the deciduomata, but not in adjacent nondecidualized tissues of the same mice. These results suggest that maternal factors associated with decidual tissue are responsible for the local expression of perforin in GMG cells.