Rational pemetrexed combined with CIK therapy plus anti-PD-1 mAbs administration sequence will effectively promote the efficacy of CIK therapy in non-small cell lung cancer.

Cytokine-induced killer (CIK) cells are heterogeneous cells composed mainly of CD3+CD56+ T cells. As an important treatment method of adoptive therapy, it has shown promising efficacy in many clinical trials, especially in combination with multidrug therapy. However, the maximal antitumor efficacy of CIK therapy in the combined administration of multidrug and CIK therapies and which administration scheme can maximize the antitumor efficacy of CIK therapy are still remain unclear. In this study, we observed that pemetrexed administration prior to the injection of CIK cells maximizes the efficacy of CIK therapy. Anti-PD-1 mAbs should be administered prior to CIK cell injection to maximize the efficacy of the therapy. However, administering anti-PD-1 mAbs after CIK cell injection significantly affects the binding rate of anti-PD-1 mAbs to the PD-1 receptor on CIK cells, affecting the efficacy of the antitumor therapy. In conclusion, our study observed that a rational administration sequence of pemetrexed combined with CIK therapy and anti-PD-1 mAbs significantly promotes the efficacy of CIK therapy, providing an experimental basis for the combination therapy mode and regimen of CIK therapy in clinical practice. We hope that this study can provide patients with lung adenocarcinoma with a prolonged survival time.

Immunity, immunopathology and vaccines against HIV?

Immunity and immunopathology of HIV infections leading to AIDS are reviewed from an evolutionary point of view. Accordingly infectious agents and host defences have co-evolved to reach balanced states where virus and host survive. While HIV has not quite yet reached an optimal balance, tuberculosis (TB), leprosy, HBV, HCV in humans or lymphocytic choriomeningitis virus (LCMV) in mice have successfully established persistence. These non- or poorly-cytopathic infections infect the next host usually before or at birth while hosts are immunoincompetent. They also infect immunocompetent hosts to persist at low levels concomitant with an ongoing T and B cell immune response that is repeatedly triggered by latent or persistent infection of extralymphatic or lymphatic host cells. This infectious or infection-immunity is the basis for cellular immunoprotection by antigen activated T cells. Because we cannot imitate this infection-immunity long-term and cannot build polyspecific vaccine combinations covering all possible neutralising variants yet, vaccines against TB, leprosy, HCV and HIV only protect transiently and incompletely.

Characterization of T cells that confer a high degree of protective immunity against tuberculosis in mice after vaccination with tumor cells expressing mycobacterial hsp65.

Mice vaccinated by injection with tumor cells expressing the Mycobacterium leprae gene for hsp65 acquire a remarkably high degree of protection against challenge with Mycobacterium tuberculosis. We used limiting-dilution analysis to assess the frequency of CD4+ CD8- and CD4- CD8+ splenocytes responding to mycobacterial hsp65 in such vaccinated mice. Cells of both phenotypes were present at very high and equal frequencies (approximately 1:100). Vaccination with live Mycobacterium bovis BCG also increased the frequencies of both phenotypes of hsp65-reactive cells equally (to approximately 1:2,500), whereas vaccination procedures that were not protective, with either dead BCG, hsp65 protein in incomplete Freund's adjuvant, or hsp65 mixed with tumor cells, resulted in preferential increase in CD4+ CD8- cells. Twelve CD4+ CD8- and twelve CD4- CD8+ hsp65-responsive T-cell clones were obtained and characterized. All showed conventional antigen recognition via major histocompatibility complex class II and class I pathways but differed in secretion of gamma interferon and interleukin 4 and cytotoxicity. In tests of antimycobacterial activity against M. tuberculosis, both in infected macrophages in vitro and by adoptive transfer of protection with T-cell clones injected into irradiated mice, the most effective clones were the most cytotoxic and secretion of gamma interferon made only a secondary contribution.

Study on the roles of CD4+ and CD8+ T cells in the expression of host resistance to Mycobacterium leprae infection induced in athymic nude mice.

The contribution of CD4+ or CD8+ T cells in the host resistance to Mycobacterium leprae was investigated. Athymic BALB/c nude mice were infected subcutaneously with M. leprae into the foot pads 1 or 3 weeks after adoptive transfer with whole, CD4 T cell-depleted, or CD8 T cell-depleted lymphocyte fractions prepared from spleen cells (SPCs) of euthymic BALB/c mice. SPCs from all of the recipient mice showed nearly the same levels of proliferative responses to phytohemagglutinin (PHA) and lipopolysaccharide, except that those of mice transferred with CD4 T cell-depleted lymphocytes showed somewhat reduced mitogenic responses to PHA. Significantly potentiated host resistance to the infection was seen, as evidenced by the obviously reduced bacterial growth in all three groups of recipient mice compared to that seen in control mice, that is, 4.7- to 6.4-log unit decreases in the bacterial loads were observed. Levels of the reduction conferred by CD 4 T cell-depleted lymphocytes were comparable to that of CD8 T cell-depleted lymphocytes. This suggests that both CD4 and CD8 T cells are important for the expression of resistance to M. leprae infection.

Infection of SCID mice with Mycobacterium leprae and control with antigen-activated "immune" human peripheral blood mononuclear cells.

The SCID (severe combined immunodeficient) mouse lacks both B and T cells and tolerates injected mononuclear cells from humans, the principal hosts of Mycobacterium leprae. A SCID mouse model of leprosy could be useful to investigate potential vaccine strategies using human cells in a context in which the growth of the organism is monitored. Initial experiments determined that SCID mice are more susceptible than normal mice to infection and dissemination of M. leprae. Cells from humans, either BCG vaccinated or from countries where leprosy is endemic, were stimulated in vitro with a number of mycobacterial antigens--whole M. leprae, M. leprae cell walls, purified protein derivative of M. tuberculosis, and Mycobacterium bovis BCG--and tested for proliferation and production of interleukin-6, tumor necrosis factor alpha, and gamma interferon. Cell walls were the most efficient and consistent in inducing all of these activities. In vitro-activated human cells retain function better after injection into SCID mice than nonactivated cells. To test the ability of cells to affect the growth of M. leprae in the footpads of SCID mice, cells from a known responder to mycobacterial antigens and from a nonresponder were activated by M. leprae cell wall antigens. The cells were harvested and coinjected with fresh M. leprae into the right hind footpads of SCID mice. After 3 months, there was no growth of M. leprae in the footpads of mice coinjected with cells from the mycobacterial antigen responder, while growth was uninhibited in mice receiving cells from the nonresponder. Future experiments will determine requirements for antigen specificity in inhibiting M. leprae multiplication.

Protection of mice against mycobacterial infection by lymphoid cell vaccination.

Intracellular parasites may thrive by inducing the host's immune system to suppress the effector immune response that otherwise limits multiplication. Hosts are traditionally immunized with the parasite antigens that induce effector immunity. Alternatively, one might vaccinate the host with the host lymphoid cells involved in suppression. Multiplication of Mycobacterium marinum was prevented by vaccinating mice with cells prepared from the popliteal lymph nodes of mice in which the organisms were multiplying logarithmically, that were inactivated by fixation with glutaraldehyde. Cells obtained later during infection, when the donor mice manifest immunity, did not protect against infection. Thus, it may be possible to influence the course of a microbial infection by immunizing the host not only with components of the organisms, but also with the host components that are exploited by the organism.

Reconstitution of Mycobacterium leprae immunity in severe combined immunodeficient mice using a T-cell line.

To test whether Mycobacterium leprae-immune T cells can confer protection against infection with leprosy bacilli, severe combined immunodeficient (SCID) mice were reconstituted with a BALB/c-derived, M. leprae-responsive, T-cell line. Flow cytometric analysis of spleen and peripheral blood cells confirmed reconstitution with T cells. In vitro lymphokine production and the proliferation of spleen cells from the reconstituted animals established that the donor cells had maintained their functional activity for the duration of the study (275 days). The transfer of immune T cells 24 hr before foot pad infection with leprosy bacilli resulted in a profound reduction in M. leprae multiplication, as compared to the nonreconstituted SCID mice. The yield of acid-fast bacilli in the foot pads of SCID mice reconstituted with the M. leprae-immune T cells also was significantly lower than that found in naive BALB/c mice, and at levels previously found only in BALB/c mice that had been immunized effectively. These experiments demonstrate that M. leprae-immune T cells home effectively and control M. leprae infection in SCID mice.

Major histocompatibility complex restriction of T-cell suppression of immune response to mycobacteria.

In earlier work, intraperitoneal (i.p.) immunization with Mycobacterium vaccae was shown to generate a T-suppressor (Ts) response but intradermal (i.d.) immunization did not. We have now studied the major histocompatibility complex (MHC) restriction of this Ts response. The ability of C57BL/6 (H-2b), BALB/c (H-2d), and the (C57BL/6 x BALB/c) F1 mice to generate suppression after i.p. immunization with 10(8) killed M. vaccae was investigated. The BALB/c and the F1 mice generated suppression, but the C57BL/6 mice failed to do so. The suppression could be ascribed to Lyt-2+, L3T4- antigen-specific T cells. The F1 suppressors generated after i.p. immunization could suppress the generation of T-cell responses to i.d. immunization with M. vaccae in the parental BALB/c but not in the C57BL/6 mice. Monoclonal anti-I-A antibody could suppress the antigen-induced proliferative response of mice primed i.d. with M. vaccae. In contrast, monoclonal anti-I-E antibody enhanced antigen-specific proliferation of spleen cells primed i.p. with M. vaccae. The suppressors generated by i.p. priming of mice with M. vaccae could also suppress the in vitro antigen-induced proliferative response of i.d.-primed spleen cells; the suppression could be blocked by anti-I-E antibody. Thus, the T-cell-mediated suppression in the above experimental model was I-E restricted. The inability of the C57BL/6 mice to generate suppression after i.p. immunization with M. vaccae was ascribed to the lack of I-E expression by mice of H-2b strain.