Darien Parker

Effect of Cyclophosphamide on Immunological Control Mechanisms

Cyclophosphamide (CY) given before immunization causes greatly increased delayed hypersensitivity skin reactions. Increased cell-mediated immunity is associated with depletion of B-lymphocytes from lymphoid tissue and a depression of those lymphocytes whose precursors turn over more rapidly. In the guinea pig, replacement studies showed that the depleted cells were not T-lymphocytes and had immunoglobulin adherent to their surface, a characteristic of B-lymphocytes. Delayed hypersensitivity reactions increased by CY include chemical contact sensitivity, the tuberculin reaction, delayed hypersensitivity to tularemia vaccine and the Jones-Mote reaction to soluble protein antigens. Pretreatment with CY can also increase the antibody response to some antigens, but depress the response to others. In addition, CY has been found to reverse immunological tolerance where this form of unresponsiveness is due to suppressor cells. CY can also enhance the immune response following depression by antigenic competition or desensitization. Other drugs with a similar, but lesser, effect include melphalan, azathioprine and methotrexate.

Effect of depletion of epidermal dendritic cells on the induction of contact sensitivity in the guinea-pig.

Guinea pig skin was depleted of Langerhans cells (LC) as assessed by ATPase and Ia staining using several techniques. The LCs were depleted either by tape‐stripping or exposure of the animals to UV‐B or UV‐C radiation. Guinea‐pigs were sensitized to 2,4‐dinitrochlorobenzene (DNCB) by application of the sensitizer to the epidermis depleted of LC. Minimally suppressed contact reactions were found in animals exposed to both wavelengths of radiation, but this was shown to be a systemic rather than a local effect. Tape‐stripping did not alter the degree of contact sensitivity when guinea‐pigs were sensitized with a large dose of DCNB. When a non‐sensitizing dose of DNCB was applied to the ear depleted of LC by tape‐stripping, contact sensitivity resulted. Although the depletion of LCs was 97% following UV‐B, 93% with UV‐C and 78% after tape‐stripping, at no time were LCs completely absent from the epidermis.

A study of the prostaglandin and thromboxane content of the central nervous tissues with the development of chronic relapsing allergic encephalomyelitis

Levels of PGE, PGF2 alpha, 6-oxo-PGF1 alpha and thromboxane (TXB2) in spinal cords and cerebellums of guinea pigs at different stages of chronic relapsing allergic encephalomyelitis (CREAE) were compared with those in Freunds adjuvant-treated, age-matched controls. PGE and TXB2 levels were found to be increased in spinal cords during acute and relapse phases of the disease. The number of lesions in the spinal cord was similarly increased in acute and relapse stages. There was, however, no similar correlation between number of lesions and eicosanoid levels in the cerebellum with the clinical stages of the disease based on hind limb paralysis. In the acute phase and remission lesion numbers were low, and high levels, similar to those found in the spinal cord, were only found in the relapse phase. Eicosanoid levels were high in the acute phase and remission, and generally low in relapse. The spinal cord levels of eicosanoids in remission and relapse correlated well with previous data obtained from the CSF of patients with multiple sclerosis.

Potentiation of T-lymphocyte function by bleomycin

Bleomycin, an anti-cancer drug, hitherto thought to have no effect on the immune response, was found to increase contact sensitivity in the guinea pig to 2,4-dinitrofluorobenzene. The drug was given in a single dose (125 mg/kg) on the day of or up to 3 days after sensitization, to achieve this effect. The drug was ineffective if given 3 days before or 4 days after sensitization. In addition, if given 2 or 3 days after sensitization, it caused increased T-cell proliferation in lymph nodes draining the skin sensitization site. It is suggested that the potentiating effect of bleomycin is not on suppressor cell function, as with cyclophosphamide, but might have an effect on local interleukin 2 production, particularly if given when T-cell proliferation is on the increase.

Isolation and analysis of circulating immune complexes in leprosy

Circulating immune complexes (CIC) were isolated by two antigen nonspecific methods from 60 leprosy patients belonging to borderline tuberculoid (BT) and lepromatous (LL) types with and without reactions. CIC were elevated in both BT and LL reactions. CIC from BT in reaction (BTR) were found to consist largely of IgG and C3, whereas, C-reactive protein could be found in CIC from LL reactions (LR). In addition, IgM and rheumatoid factor were demonstrated in the complexes of LR patients who had mainly arthritis. Antimycobacterial antibody was seen in the complexes of two-thirds of LR patients who had predominantly skin manifestations as part of their reaction. The relevance of these findings to the clinical manifestations of different types of reactions is discussed.

Effects of adriamycin, 4-hydroperoxycyclophosphamide and ASTA Z 7557 (INN mafosfamide) on the release of IL-2 and IL-1 in vitro

Adriamycin (ADR), 4-hydroperoxycyclophosphamide (4-OOHCYP) and the new cyclophosphamide derivative AZ 7557 (AZ) were tested for their effects on the release of the Interleukins IL-2 and IL-1 from rat spleen cells and peritoneal exudate macrophages respectively. ADR was found to enhance IL-2 release and less effectively IL-1 release. 4-OOHCYP and AZ were found to inhibit IL-2 release but had no effect on IL-1 production. It is suggested that the modulation of IL-2 levels by these drugs is unlikely to be mediated by their effects on IL-1.

Potentiation of release of interleukin-2 by bleomycin

The antineoplastic drug bleomycin, which has not been shown to have immunosuppressive activity, was tested for its effect on concanavalin A-induced interleukin-2 production. When the drug was added to splenocytes of Lewis rats or Balb/c mice in the presence of concanavalin A, in optimal conditions for interleukin-2 production, no detectable effects were seen. However, using a suboptimal dose of concanavalin A, bleomycin increased interleukin-2 release significantly. This effect was achieved using less than 1 microgram/ml bleomycin. In addition, bleomycin was tested for its ability to alter interleukin-1 production by peritoneal exudate macrophages. The drug seems to increase the release of interleukin-1 from peritoneal exudate macrophages of Lewis rats without any lipopolysaccharide added or with a suboptimal concentration of lipopolysaccharide. It is suggested that bleomycin, and probably other cytotoxic drugs, may modulate the immune response through its effects on the release of immunostimulating cytokines such as interleukin-1 and -2.

Delay in the Development of the Allergic Response to Metals Following Intratracheal Instillation

Intracheal intubation with the soluble metal salts potassium dichromate (K2Cr2O7) and nickel sulphate (NiSO4) causes a delay of up to 8 weeks in the development of delayed hypersensitivity to the specific agent. It is suggested that absorption of sensitizers by the respiratory route may, under certain circumstances, induce a state of specific immunological unresponsiveness, rather than necessarily lead to the development of a state of allergic sensitivity.

The Value of an Assessment of Erythema and Increase in Thickness of the Skin Reaction for a Full Appreciation of the Nature of Delayed Hypersensitivity in the Guinea Pig

Delayed type skin reactions in guinea pigs have been assessed by measuring three parameters: increase in skin thickness, diameter of erythema and intensity of erythema. Some groups of animals were immunized with different protein antigens in Freunds complete adjuvant with or without cyclophosphamide (CY) pretreatment; others received a single high dose of antigen intravenously at the time of immunization. The results emphasize the importance of measuring all three parameters for several days after skin testing. The intensity or erythema was found to be an especially useful parameter for assessing CY-induced modification of delayed hypersensitivity (DH) reactions. The increase in skin thickness, which can be measured objectively, was also valuable as both immediate and DH reactions are characterized by induration. The diameter of erythema could only be measured accurately for a short time after skin testing. Furthermore, the effects of intravenous antigen and CY pretreatment were not reflected by that parameter.

Further evidence for non-T-cell regulation of delayed hypersensitivity in the guinea pig

Abstract The nature of the suppressor activity in the spleens of guinea pigs immunized with dinitrophenyl-bovine γ-globulin in Freunds incomplete adjuvant was investigated. An anti-T-cell serum was prepared in rabbits and, after extensive absorption, showed specific killing for T-lymphocytes. After treatment with this antiserum and complement, spleen cells from animals immunized with the antigen in Freunds complete adjuvant showed marked reduction in ability to transfer sensitivity to normal recipients. However, when immune spleen cells, treated in the same way, were transferred into antigen immunized animals which had been pretreated with cyclophosphamide, the suppressor activity was unaltered. These results confirm earlier impressions that the regulation of delayed hypersensitivity reactions in the guinea pig is normally mediated by non-T-cells.