Central role of T lymphocytes in specific recognition of tumor antigens in 51Cr-leukocyte adherence inhibition

Effector lymphocyte response to homologous tumor antigens in various stages of malignant disease as monitored by leukocyte adherence inhibition--cell mediated immunity (LAI-CMI)

Leukocyte adherence inhibition-cell mediated immunity (LAI-CMI) studies were performed on leukocytes obtained from patients with various stages of breast cancer, colon carcinoma and lung cancer in order to monitor cell mediated immunity during tumor progression. In the presence of autologous serum, all patients with localized tumors showed positive LAI-CMI indexes (greater than 20%), while significant reduction of homologous tumor antigen recognition as measured by the LAI-CMI responses was observed in nearly all patients with Stage IV breast cancer, Duke C colon cancer and Stage III lung cancer. On substituting autologous serum with normal AB serum, leukocytes from patients with large tumor burdens responded to homologous tumor antigens. These results indicate the existence of organ-specific serum factor(s) which may mask the receptor sites on effector cells for tumor recognition. Patients with such serum blocking factor(s) showed significant increase of IgG immune complexes IgM, IgA and alpha-2-macroglobulins. Application of a protein A affinity column purification resulted in a major reduction of IgG and other immune globulins but not of alpha-2-macroglobulin. The blocking effects of autologous serum, however, were not completely abrogated by filtration on the protein A column, thus suggesting that SBF may be heterogeneous in nature and may occur in other serum protein fractions beside the immune globulins.

Immunopotentiation of impaired lymphocyte functions in vitro by isoprinosine in prodromal subjects and AIDS patients

Immunomodulative actions of isoprinosine were tested in 100 prodromal homosexual males and 23 patients who have been diagnosed with AIDS. All subjects showed reduced T helper cells although T suppressor cell counts were normal. Proliferative responses, particularly T cell-dependent B cell function, were severely impaired in prodromal and AIDS subjects. Upon co-cultivation of their lymphocytes with isoprinosine, significant upward modulation, and in some cases, normalization, of lymphocyte functions as monitored by PHA- and PWM-induced blastogenesis was achieved in prodromal subjects. Similar degrees of modulation but not normalization of lymphocyte functions were observed in patients with severe symptoms of AIDS.

Modulation of T- and B-lymphocyte functions by isoprinosine in homosexual subjects with prodromata and in patients with acquired immune deficiency syndrome (AIDS)

Male prodromal homosexuals and patients with acquired immune deficiency syndrome (AIDS) exhibited similar immunological abnormalities but by different degrees. A reduction in the number of circulating T lymphocytes bearing the T-4 surface marker led to an altered ratio of Th to Ts subpopulations in both groups of subjects. Total numbers of suppressor cells (Ts) remained virtually similar in both study groups to that of the control subjects. Proliferative responses to T-cell mitogen (PHA) and T cell-dependent B-cell mitogen (PWM) were severely impaired in prodromal subjects and more so in the AIDS group. The response to PWM was unrelated to the total number of suppressor T cells but was associated with a significant decrease in helper T-cell number. The impaired lymphocyte functions of immunosuppressed subjects were potentiated by coincubation with isoprinosine in a selective fashion. While the percentage of upward modulation among homosexuals with normal lymphocyte functions was comparable to that obtained in control subjects, a higher degree of augmentation was achieved in AIDS patients and in prodromal subjects with impaired blastogenic responses. In none of the AIDS patients with severe immunodeficiencies, however, was the lymphocyte functions restored to the normal range established in the heterosexual controls. These results suggest the feasibility of eventual prophylactic utilization of isoprinosine in male homosexuals at high risk of developing AIDS.

Amplification of lymph node cell tube leukocyte adherence inhibition (LAI) reactivity by leukocyte adherence inhibition factor (LAIF)

This investigation examines the immunologic basis for specific antigen-induced tube leukocyte adherence inhibition (LAI) reactivity of draining lymph node cells (LNC) from dogs with canine transmissible venereal sarcoma (CTVS). CTVS regressor LNC, macrophage-depleted LNC, and enriched T lymphocyte fractions, but not enriched B lymphocyte fractions, were specifically reactive to CTVS antigen extract in direct tube LAI. In addition, regressor LNC amplified tube LAI responses by generating supernatants with leukocyte adherence inhibition factor (LAIF) activity for normal dog indicator LNC and enriched peripheral blood mononuclear cells (PBMC) in an indirect tube LAI assay. However, macrophage-depleted LNC and enriched T lymphocyte fractions failed to generate supernatants with LAIF activity, suggesting that macrophage accessory cells play a central role in the amplification of tube LAI. Interestingly, CTVS regressor peripheral blood leukocytes (PBL) and PBMC, which were specifically reactive in direct tube LAI, also failed to generate supernatants with LAIF activity. These findings demonstrate a distinction between LAIF-mediated amplification and direct tube LAI reactivity, and suggest that leukocyte populations with differing cellular proportions and from different immunologic compartments may participate in tube LAI via different mechanisms.

A leukocyte adherence inhibition (LAI) assay of anti-tumor immunity in rats using selective radioimmunological assessment of adherence of T lymphocytes and monocytes

A new, highly sensitive micro-glass-tube leukocyte adherence inhibition (LAI) assay has been developed to detect anti-tumor sensitization in a rat colon carcinoma system. This technique requires fewer cells and smaller amounts of antigen preparations than the previous glass tube method. The microscopic enumeration of adherent cells is replaced by a cellular radioimmunoassay (CRIA) which utilizes antibodies binding to mononuclear cells (MNC) and 125I-labelled protein A. Antigen preparations were shown to be adsorbed to glass. Precoating of glass vials with fetal calf serum or antigen preparations was shown to cause a major increase in nonspecific LAI. The new LAI technique is designed to minimize such nonspecific LAI. By applying an anti-T-cell monoclonal antibody (McAb), an anti-Ig antiserum and an anti-monocyte (MC) antiserum it became possible to assess selectively the change of adherence of T cells, B cells and monocytes. The specificity of the assay was demonstrated with anti-T-cell and anti-MC reagents in criss-cross experiments using two defined antigens and different tissue extracts as test antigens. The LAI response of peripheral blood MNC was examined after the subcutaneous isografting of 1 X 10(7) X-irradiated DMH-W49 colon carcinoma cells. Six days after sensitization all the rats showed an LAI response detectable with anti-T-cell and anti-MC reagents, which gave considerably higher LAI indices than anti-MNC antiserum. After the subcutaneous isografting of 1 X 10(5) viable DMH-W49 cells, 12 of 24 rats (50%) showed an LAI response detectable with the anti-MNC antiserum during a 3-week follow-up period. On the other hand, an LAI response was detected in all the 14 tumor-inoculated rats tested when the adherence of T lymphocytes and monocytes was assessed selectively.

Detection of different states of immunity to colon cancer in rats by a leukocyte adherence inhibition (LAI) assay assessing the adherence of T lymphocytes and monocytes selectively

Peripheral blood mononuclear cells (MNC) of rats, which had received a subcutaneous inoculation of either viable or X-irradiated syngeneic DMH-W49 colon carcinoma cells, were investigated sequentially for sensitization against tumor-associated antigens by a new micro-glass-tube leukocyte adherence inhibition (LAI) assay. The number of adherent cells of MNC subpopulations was estimated by a cellular radioimmunoassay (CRIA), which utilizes anti-monocyte (MC) antiserum or anti-T-cell monoclonal antibody (McAb) and 125I-labelled protein A. LAI reactivity was demonstrated in rats sensitized with X-irradiated tumor cells when assessing the adherence of both T lymphocytes and monocytes. It was found that reactivity with the two different types of indicator cells did not usually coincide in time. The same phenomenon was also observed in tumor-bearing rats although with lower levels of LAI reactivity. In both groups the LAI response detected by anti-T-cell reagent mostly appeared earlier after tumor-cell inoculation than the response demonstrated by anti-MC serum. The T-lymphocyte-associated reactivity also disappeared more rapidly. These results suggest that different states of immune reactivity are reflected in LAI responses involving T lymphocytes and monocytes as indicator cells.