Sei Tokuda

Modulation of the in vitro murine immune response by met-enkephalin

The in vitro priming of mouse spleen cultures with sheep erythrocytes (SE) was used to study the modulation of immune function by met-enkephalin (MENK). In these studies, suboptimal, optimal, and supraoptimal concentrations of SE were used to manipulate the plaque-forming cell (PFC) responses of cultured spleen cells. MENK, at a concentration of 10(-7) M, was able to abolish the high antigen dose-induced suppression of the PFC response, but was unable to increase the PFC response of cultures treated with suboptimal doses of antigen. On rare occasions when the supraoptimal dose of antigen did not suppress the immune response, the addition of 10(-7) M MENK to the culture medium suppressed the PFC response. Naloxone was unable to block the effect of MENK. These results indicate that the nature of the immune response must be taken into consideration when evaluating the effect of opioid peptides on immune function. We propose that MENK possesses a dual modulatory role, with the abilities to suppress a strong immune response and reverse high antigen-induced immunosuppression.

Differential immune response in two handled inbred strains of mice

C57BL/10J and BALB/cJ mice, outfostered at birth to C3H/2Ibg dams were subjected to handling on days 1 through 20 of life. Their plaque forming cell (PFC) response to sheep red blood cells as adults on day 5 post-immunization was compared to the PFC response in non-handled control mice. The PFC response of handled C57BL/10J mice was significantly suppressed compared to the PFC response in non-handled mice while the response of the handled and non-handled BALB/cJ mice was not significantly different.

Effect of Low-dose Irradiation upon T Cell Subsets Involved in the Response of Primed A/J Mice to SaI Cells

A/Jax (A/J) mice primed to Sarcoma I (SaI) exhibit an augmented response in association with low-dose (0.15 Gy) irradiation. This phenomenon is best demonstrated in tumour neutralization (Winn assay) or cell transfer experiments utilizing mice depleted of thymus-derived (T) cells. It is particularly dependent upon the duration of priming and the growth characteristics of the tumour in the primary host. The importance of these two variables appears to relate to their influence upon the cell types responsible for the host response, and includes both an effector and a suppressor component. Radiation-induced inhibition of the suppressor component appears responsible for low-dose augmentation and results in injury to a T cell of the Lyt-1-2+ phenotype. In Winn assays employing equal numbers of immune spleen cells and SaI cells, the smallest tumours are associated with Lyt-1-positive (Lyt-1+2- and Lyt-1+2+) cells and exposure to 0.15 Gy markedly inhibits their anti-SaI activity. Thus, even though the effect is in the opposite direction, both the effector and suppressor components of the anti-SaI response in A/J mice are exceedingly radiosensitive.

Dual immunomodulation by met-enkephalin

Met-enkephalin (MENK) is an opioid peptide that is released during physiological stress and is reported to either up-regulate or down-regulate the immune response. Our previous experiments showed the ability of 10(-7) M MENK to modulate the plaque-forming cell (PFC) response of Mishell-Dutton cultures treated with low, optimal, and large concentrations of sheep erythrocyte (SE) antigen. In the present series of experiments the PFC response was measured in splenocyte cultures challenged with incremental concentrations of SE in the presence of 10(-7) M MENK. These experiments illustrate what we consider to be true modulation, i.e., the ability of MENK to modulate immune function only during the presence of a strong immune signal. When the immune signal was strong, as represented by a strong PFC response, MENK suppressed the PFC response. Conversely, when the strongest immune signal was high-antigen suppression of the PFC response, MENK overcame the suppression and frequently returned the PFC response to a greater than optimal level. In a true modulatory fashion MENK had no effect in those regions of the dose-response curve where there was insufficient antigen to induce a strong immune signal.

Opioid Peptide Effects on Leukocyte Migration

The recognition that morphine bound stereospecifically to receptors in the brain to exert its effects led to a concerted search for an endogenous ligand for the opiate receptor (Terenius and Wahlstrom, 1975). In 1975, peptides which bound to the opiate receptor were isolated from porcine brain extracts and characterized (Hughes et al., 1975; Hughes et al., 1976). The first opioid peptides characterized were the pentapeptides methionine-and-leucine enkephalin (met- and leu-enkephalin). Simultaneously, a larger (31 amino acid), more active peptide containing the amino acid sequence of met-enkephalin as its first 5 N-terminal amino acids was isolated from porcine and camel pituitary and was named beta-endorphin (a contraction for “endogenous morphine”) (Teschemacher et al., 1975; Li and Chung, 1976). Beta-endorphin and alpha-endorphin (amino acids 1–16 of beta-endorphin), gamma-endorphin (amino acids 1–17 of beta-endorphin), (Ling et al., 1976), as well as other neuropeptides, may arise from a 31 Kd glycoprotein, the proopiomelanocortin molecule (reviewed by Frederickson and Geary, 1982). The discovery that beta-endorphin is released from the pituitary along with the steroidogenic hormone, adrenocorticotropin (ACTH) in response to acute stress suggests that in addition to its numerous actions in the central nervous system, beta-endorphin, like ACTH, also has peripheral hormonal effects (Guillemin et al., 1977; Bossier et al., 1977). The release of both ACTH and beta endorphin may be under the control of the hypothalamic peptide, corticotropin releasing factor (CRF) in some species (Hook et al, 1982 and Knepel et al, 1984).

Suppression of the Graft-versus-Host Reaction by Passive Immunization of Donor against Recipient Antigens

Summary A graft-versus-host reaction was produced by injecting newborn A/J mice with C57B1/Ks spleen cells which resulted in 96.8% mortality. Passive immunization of the spleen donors with antibody against the A/J tissue antigens reduced mortality to 60.0%. Spleen cells taken from donors passively immunized up to at least 8 days previously were depressed in their ability to mount a graft-versus-host reaction.

The in vivo effects of opioid peptides on the murine immune response.

We have previously reported that met-enkephalin has dual immunomodulatory properties in vitro. We have continued this investigation using an in vivo system. In this study, Alzet miniosmotic pumps were loaded with either met-enkephalin, DTLET or FK 33-824 and were surgically implanted into BAF1/J mice. Twenty-four hours after pump implantation, mice were challenged with sub-optimal, optimal or supraoptimal immunizing doses of antigen. The immune response was assessed 4 or 5 days after primary immunization. FK 33-824, a met-enkephalin analogue, had no effect on the response of mice challenged with a suboptimal antigen dose. However, FK 33-824, at a pump concentration of 10(-3) M, suppressed the response against optimal challenge doses of antigen. At a pump concentration of 10(-8) M, FK 33-824 suppressed, enhanced or had no effect on the supraoptimal antigen dose-induced immune response. The suppressive effect of FK 33-824 in mice immunized with either optimal or supraoptimal doses of antigen was blocked by naloxone. Met-enkephalin and its delta opioid receptor specific analogue, DTLET, had no effect on the immune response to optimal antigen immunization. These results indicate that FK 33-824 has in vivo immunomodulatory activity and provide evidence that opioid peptides may either upregulate or downregulate the in vivo immune response depending on the strength of the response.

Evidence of immunosuppression in the genetically epilepsy-prone rat

Immune system function was examined in the genetically epilepsy prone (GEPR-9) rat and non-epileptic Sprague-Dawley control rats. Significant decreases in direct and indirect plaque-forming cell responses were observed in GEPR-9 rats immunized with sheep erythrocytes. Serum levels of IgM were also decreased in non-immunized GEPR-9 rats, providing additional evidence of immunosuppression. However, total serum levels of IgG were three-fold greater in GEPR-9 rats compared to control. These results suggest that the nature of the immune system deficit in the GEPR-9 is complex and may involve an active T-cell population stimulating an overproduction of IgG leading to a diminished capacity to respond to new antigen challenges. This immunological defect may underlie the enhanced susceptibility of GEPR-9 rats to infectious agents. The specific cause of this immune dysfunction is not known. Possible etiological factors include a breakdown in the communication between cells within the immune system or an alteration of neuroendocrine modulation of immune responses.

Detection of H-Y antigen on human male leukocytes

Abstract Using the Staphylococcus aureus binding technique, we have demonstrated H-Y (‘male’) antigen on human male leukocytes.

Chymopapain C, an Immunosuppressive Protease: I. Partial Purification and Characterization

Summary This study has demonstrated the presence of a proteolytic enzyme, chymopapain C, in the extract of Carica papaya. This enzyme differs significantly from papain in enzymatic activity, thermal half-life and action of human IgG. However, this enzyme is similar to commercial chymopapain in its activity and in its digestion of human IgG, but differs in molecular weight, thermal half-life and relative electrophoretic mobility.