Search

Mononuclear cells, obtained from the spleens and lungs of influenza virus-seropositive C57BL/6 mice at 2 to 4 days after re-infection with homologous virus (strain A/Bangkok/1/79), produced a low m.w. factor in vitro that prevents the biologic expression, but not production, of the lymphokine, leukocyte migration inhibition factor (LIF). The low m.w. factor inhibited LIF activity without destroying the LIF molecule inasmuch as simple dialysis restored lymphokine activity to culture supernatants. Production of the low m.w. factor was observed from 2 to 4 days after re-infection, at which time the delayed-type hypersensitivity response to viral Ag was suppressed. In contrast, LIF was produced by splenocytes and lung mononuclear cells obtained at all times tested after re-infection (from 2 to 30 days). Production of the low m.w. factor required re-infection of influenza A virus-seropositive mice with type A virus; re-infection with influenza B virus failed to induce production. Ag specificity was also required in vitro for splenocytes to produce the factor; cells from type A virus-re-infected mice required type A Ag stimulation. Cell depletion studies with mAb plus C revealed that macrophages and T cells along with Ag stimulation were required for factor production by spleen cells. However, mononuclear cells obtained within 4 days from the lungs of re-infected mice did not require in vitro Ag stimulation for production of the low m.w. factor, and factor production was dependent upon the presence of CD4+ (L3T4) cells in the culture. Fractionation of culture supernatants over a Sephadex G-50 column indicated that the factor had a molecular mass of 2 to 3 kDa, and by FPLC chromatofocusing over a Mono P column, the factor eluted at a pH of approximately 8.2. Thus, re-exposure of influenza virus-seropositive mice to homologous virus resulted in the production of a low m.w. factor that prevented the biologic expression of LIF, but not its production. Lymphokines are an important component of the delayed-type hypersensitivity response; the presence of mononuclear cells secreting a low m.w. factor and LIF concomitantly at the site of virus replication (lungs) and the capacity of the factor to block the biologic expression of LIF in vitro suggest that the factor may have a role in the regulation of a delayed-type hypersensitivity response in vivo during re-infection.

Although functional histamine receptors have generally been restricted to those human T lymphocytes expressing suppressor cell functions, more recent evidence suggests that histamine receptor-bearing human T lymphocytes are functionally heterogeneous and capable of other immunomodulatory activities. Lymphocyte chemoattractant factor (LCF) is a cationic sialoprotein with an apparent m.w. of 56,000, whose production is limited to histamine-type 2 receptor-bearing human T cells. LCF is selectively chemokinetic for T lymphocytes, and presumably contributes to the recruitment of unsensitized effector lymphocytes at inflammatory sites. In addition to LCF, Sephadex G-100 gel filtration of histamine-induced lymphocyte supernatants revealed two regions of migration inhibitory activity for human blood T and rat splenic lymphocytes. These regions corresponded to m.w. of 70,000 to 80,000 (LyMIF75K) and 30,000 to 40,000 (LyMIF35K). LyMIF75K had a single pI of 7.5 to 8.0, and its biologic activity was sensitive to trypsin but not to neuraminidase or heat (56 degrees C). LyMIF35K had a single pI of 8.5 to 8.8, and its biologic activity was sensitive to neuraminidase and heat but not to trypsin. These LyMIFs therefore appeared to be distinct from one another and physicochemically different from other migration inhibitory lymphokines. All three lymphokine activities appeared within 4 hr of incubation. The minimum concentration of histamine required to stimulate production of the LyMIF was 10(-6) M. Lymphocytes that did not adhere to a histamine affinity matrix were unable to produce either LyMIF upon subsequent stimulation with histamine or concanavalin A (Con A). Lymphocytes incubated with histamine and diphenhydramine produced LCF but neither LyMIF, whereas cells incubated with histamine in the presence of cimetidine produced both LyMIF but not LCF. These data suggest that a subset of lymphocytes defined by the presence of histamine-type 1 receptors are capable of producing two distinct species of lymphocyte migration inhibitory activity. These cells may contribute to the immobilization of effector T lymphocytes chemokinetically attracted to certain inflammatory sites.

Leukocyte migration inhibitory factor (LIF) is produced by lymphocytes with receptors specific to sensitizing antigens. This principle was used to detect possible antigenic differences between sperm of autoimmune and nonautoimmune men. Sixteen fertile and 91 infertile couples were screened for cytotoxic and hemagglutinating antibodies to sperm from their husbands and controls. Their lymphocytes were tested for the production of LIF to sperm extracts and seminal plasma from the husbands and controls by a direct leukocyte migration inhibition assay. Twenty-nine of 35 men producing LIF to sperm and/or seminal plasma were positive for sperm antibodies (p = 0.0004, vs sperm antibody-negative controls). Twenty-three of 29 wives with LIF production had sperm-autoimmune husbands (p = 0.04). Leukocyte migration was significantly inhibited in sperm-autoimmune men by autologous sperm extracts and seminal plasma in contrast to control sperm extracts and seminal plasma (p = 0.0006 and 0.001, respectively). The wives of autoimmune men had significantly higher LIF responses to their husbands' sperm extracts than to other antigens (p = 0.02). Men with cytotoxic antibodies in their seminal plasma produced LIF to autologous sperm (p = 0.001). It is suggested that certain sperm and seminal plasma antigens of autoimmune men may lead to specific humoral and cell-mediated immune responses in both partners.