Antigen-specific lysis in vitro of lymph node cells of intact mice injected with RNA from viable lymph node cells of immunized animals]

Supernatant fluid obtained after centrifugation of the suspension of viable lymph node cells of immunized animals proved to induce in vivo in the lymph node cells of intact mice sensitivity to lysis with a specific antigen in vitro. This property was possessed after chromatography of the supernatant fluid on Sephadex G-200 by the 3rd fraction (MW about 30000 dalton). DNA-ase, trypsin or deproteinization failed to influence whereas RNA-ase inactivated this fraction in respect to the inducing properties.     

Inhibition of antibody-dependent cellular cytotoxicity by autologous lymph node cells.

A population of lymph node cells that lack the usual T, B, or K cell markers was found to inhibit autologous spleen cells from mediating antibody-dependent cellular cytotoxicity (ADCC) to antibody-coated chicken erythrocytes. Inhibitor cells were not susceptible to treatment with anti-Thy 1.2 or anti-Ig and C; they did not adhere to Sephadex G-10, to nylon wool, or to monolayers of sheep erythrocytes (E) or erythrocytes plus 7S antibody (EA). After a brief (4-min) exposure to 45 degrees C, the ability to inhibit was lost whereas other cellular responses remained intact. ADCC mediated by nonadherent splenic effector cells (presumptive K cells) was highly susceptible to inhibition. Possible mechanisms for and implications of lymphocyte-mediated inhibition of ADCC are discussed.     

In vitro heterologous cytotoxicity by T effector cells from mice immunized with Sindbis virus.

An in vitro correlate of cell-mediated cross-protection among alpha-viruses was demonstrated by cytotoxicity of Sindbis-immune spleen cells from mice to both Sindbis and Semliki Forest virus (SFV)-infected target cells. This cytotoxicity was shown to be mediated by the T cell population of the spleen and was independent of the presence of macrophages or B cells. The time when the level of the lymphocyte-mediated cytotoxicity (LMC) to SFV-infected cells was maximal coincides with the time when immunity to SFV is maximal in vivo, as reported previously, and when adoptive immunity to SFV can be transferred. After one i.p. injection of Sindbis virus, the level of homologous LMC was higher than the level of heterologous LMC. However, following a second injection of Sindbis virus as immunogen, at a time when the mice are cross-protected to SFV, the heterologous LMC was considerably higher than homologous LMC. We propose that there is suppression of the effector T cells specific for Sindbis-infected cells after the second immunizing injection, probably by homologous antibody. In contrast, there appears to be an anamnestic cell-mediated response to SFV.     

Development of IgE-forming cells in vitro from rat mesenteric lymph node cells.

Mesenteric lymph node cells from normal rats and rats infected with Nippostrongylus brasiliensis (Nb) were cultured with pokeweed mitogen (PWM) or Nb antigen, and the development of IgM-, IgG2a-, or IgE-containing cells was assessed by immunofluorescence. Normal lymph node cells stimulated with PWM developed into both IgM- and IgE-containing cells, whereas similar stimulation of cells from Nb-infected rats resulted in the development of IgM-, IgG2a-, and IgE-containing cells. The in vitro plasma cell response to PWM was dependent on the presence of T lymphocytes. Lymph node cells from Nb-infected rats responsed to Nb antigen and developed into plasma cells of IgM, IgG, and IgE classes. The response was antigen specific and required antigen-primed T cells. Depletion of IgE-bearing cells or IgM-bearing cells before stimulation with either PWM or Nb antigen diminished the level of IgE forming cell development, suggesting that IgE-IgM double bearing cells are precursors of IgE-forming cells. The distribution of the three isotypes among the If-forming cells that developed in response to PWM was influenced by the source of both B and T cells. When B cells from Nb-infected rats were employed as a source of precursors, T cells from infected animals were more effective than normal T cells for the development of IgE-forming cells, whereas the latter cells were more effective for the development of IgG2a-forming cells than T cells from infected animals.     

In vitro development of a primary antibody response with lymph node cells.

Utilizing a variety of lymphoid tissues from three common laboratory species, comparative studies were performed to investigate the competence of the dissociated cells to respond to a heterologous erythrocyte with the development of specific plaque-forming cells. Dissociated spleen cells harvested from BDF1 mice consistently developed specific plaque-forming cells (PFC) to sheep red blood cells (SRBC), while hamster spleen cells inconsistently developed specific antibody-forming cells to SRBC. Under identical conditions, guinea pig spleen cells did not develop significant numbers of PFC to SRBC. However, lymph node cell cultures of all three species tested yielded specific PFC. In the mouse and hamster lymph node cell cultures, the yield of PFC per culture or per 10⁶ recovered viable cells was always greater than the yield from companion spleen cell cultures. Guinea pig mesenteric lymph node cell cultures developed the major PFC response to SRBC, while both mesenteric and peripheral lymph node cell cultures from hamsters were equivalent in their response to SRBC. The data demonstrate that it is possible to develop a primary antibody response to SRBC in vitro utilizing normal endogenous hamster or guinea pig lymphoid cells, if lymph nodes are the source of cells.     

Increase in the number of antibody producing cells during combined cultivation of lymph node cells from immunized animals with intact bone marrow cells]

An increase in the amount of direct and indirect plaque-forming cells in mixed cultures of lymph node cells from mice primed and challenged with sheep red blood cells with syngenic and allogenic bone marrow cells from intact donors was observed. The amount of plaque-forming cells in mixed cultures reached the maximum level in 9--11 hours of cultivation and then fell to the initial level. The authors believe that in mixed cultures of lymph node cells from immune mice and bone marrow cells from intact donors there occurs an involvement into the antibody synthesis of new cells of one of the two cell populations cultured.     

Resistance to tumor growth in guinea pigs immunized with lyophilized tumor cells

Summary Living BCG, killed Mycobacterium tuberculosis cells, or BCG cell walls (CW) augmented the immunogenicity of lyophilized syngeneic ascites hepatoma (line 10) of strain-2 guinea pigs. Effective vaccine contained living BCG and lyophilized line-10 cells, or mycobacterial cells or CW attached to oil droplets and lyophilized line-10 cells. Protection against the challenge tumor was evident 14 or 21 days after one administration of either vaccine.