Immune-based therapeutics: scientific rationale and the promising approaches to the treatment of the human immunodeficiency virus-infected individual.

The primary approach to therapy for infection with human immunodeficiency virus (HIV) continues to be centered around antiretroviral agents that have conferred significant clinical benefits. The considerable degree of immunologic dysfunction in HIV infection, however, has led to intense interest in methods of immune stimulation and reconstitution. Immunomodulatory intervention in HIV infection is highly controversial. Over the years a number of immunomodulatory agents--many with only a poor rationale for their clinical use--have been evaluated. In this review we concentrate on immunomodulatory approaches that are currently being investigated. We group these interventions, reviewing the rationale and clinical data for each category: passive immunity (administration of immunoglobulins and use of apheresis), thymic hormone treatment, cytokine treatment (administration of interleukins, tumor necrosis factor, and interferons), adoptive cellular immunity, and therapeutic vaccination. At present, the only interventions supported by data from well-controlled studies are the parenteral administration of interferon alpha to patients with HIV-associated Kaposi's sarcoma and the administration of pooled immunoglobulin (to decrease the rate of bacterial infections) to children who cannot take trimethoprim-sulfamethoxazole. However, several other approaches under development show promise in reversing some of the immune deficits of HIV infection. Clinical evaluation of these approaches should yield valuable insights into the immunopathogenesis of HIV infection, and these insights should facilitate the formulation of new modalities of treatment.

Modulation of HLA antigen expression on conjunctival fibroblasts by gamma-interferon.

We investigated the ability of recombinant human gamma-interferon (rhIFN-gamma) to induce class II HLA antigen expression on human conjunctival fibroblasts in cell culture. Cultures were established by explanting subconjunctival tissue from normal donor globes. Fibroblasts were treated with rhIFN-gamma at concentrations ranging from 1 to 500 units/ml and incubated for 1, 3 and 6 days. HLA antigens were detected by immunofluorescence using monoclonal antibodies in conjunction with flow cytometry. Class I antigen was identified using a monoclonal antibody directed against Beta-2 microglobulin (a component of the class I antigen complex). Class II histocompatibility antigens were detected using monoclonal antibodies specific for HLA-DR, HLA-DP and HLA-DQ. Class I antigen was present on all cells prior to induction and showed a trend toward increased density after treatment with rhIFN-gamma. Class II antigens were absent before induction with rhIFN-gamma. After treatment with rhIFN-gamma, class II antigens were induced in a dose- and time-dependent fashion. HLA-DR expression was most sensitive to induction by rhIFN-gamma, followed by HLA-DP, and then HLA-DQ. The up-regulation of HLA class I antigen expression and the inducible expression of class II antigens following exposure to rhIFN-gamma suggest that conjunctival fibroblasts have the potential to participate in immunologic diseases of the external eye.

B-cell dysfunction following human bone marrow transplantation: functional-phenotypic dissociation in the early posttransplant period.

We investigated the defect in humoral immunity that occurs following bone marrow transplantation (BMT). B cells from BMT recipients were tested for their ability to undergo the sequential steps of activation (RNA synthesis on stimulation with anti-mu or PMA), proliferation (DNA synthesis on stimulation with anti-mu plus B cell growth factor [BCGF], phorbol myristate acetate [PMA], or Staphylococcus aureus Cowan I [SAC] strain bacteria) and differentiation (Ig synthesis stimulated by T cell replacing factor [TRF]). B-cell maturation-associated cell surface markers were simultaneously investigated. "Early" (less than 10 months) posttransplant patients demonstrated defective B-cell activation and also failed to undergo normal proliferation and differentiation. Despite their functional impairment, the early patients' B cells displayed an "activated" phenotype with increased proportions of B cells displaying CD23 (a BCGF receptor) and decreased proportions of Leu 8+ B cells. Furthermore, these patients were uniquely distinguished by the fact that their B cells only weakly (if at all) expressed the CD19 antigen. In contrast, B cells from "late" patients (greater than or equal to 10 months post-BMT) activated and proliferated normally and displayed a normal cell surface phenotype, yet were unable to differentiate to high rate Ig secretion with TRF. Our results suggest a phenotype/function dissociation in early posttransplant period. With time, B cells in BMT patients acquire a normal surface phenotype and can activate and proliferate normally, yet still demonstrate a block in terminal differentiation.

Failure of B cells in common variable immunodeficiency to transit from proliferation to differentiation is associated with altered B cell surface-molecule display.

B cells from patients with common variable immunodeficiency (CVI) were investigated as to their surface-molecule display and their functional ability to transit through defined in vitro developmental stages. Patients' B cells were analyzed by dual color-flow cytometry and found to have an abnormal surface-molecule display characterized by depressed Leu 8 and CD21 expression. Membrane immunoglobulin (mu, delta, and light chain) were normally displayed. The lack of Leu 8 and CD21 expression did not represent the normal loss of these antigens from B cells with activation because the cells did not demonstrate enhanced display of activation markers, nor did they demonstrate enhanced display of early B cell molecules, such as common acute lymphocytic leukemia antigen or CD5. Small resting B cells from the patients were isolated and tested for their ability to respond functionally to a series of activation, proliferation, and differentiation signals. B cells from 14 of 17 patients failed to transit from proliferation to differentiation with increased immunoglobulin production when B cells were stimulated with T cell replacing factor +/- phorbol myristate acetate. Cells of one patient failed to proliferate, whereas B cells from the remaining two patients with CVI did not undergo activation (size change and RNA synthesis) when they were exposed to antimu antibody or low-dose phorbol myristate acetate. These studies demonstrate that most patients with CVI have B cells displaying an altered-surface phenotype that is associated with a specific functional defect in transiting from cell proliferation to differentiation and immunoglobulin production.

T cell lines established from multiple sclerosis cerebrospinal fluid T cells using human retroviruses.

Cerebrospinal fluid (CSF) lymphocytes from patients with multiple sclerosis (MS) were transformed with human T cell leukemia/lymphoma virus (HTLV I and HTLV II) and the resulting cell lines characterized by cell surface phenotyping and functional assessment. The lines were predominantly of the CD4 helper/induce phenotype although the HTLV II lines contained 10-20% CD8+ cells. The lines appeared to be activated cells; the majority were TA1+, HLA-DR+, and TAC+ (CD25+). Interestingly, they were OKT10- (CD38-). Functionally, the lines contained no natural killer (NK) activity and were modestly cytotoxic in the antibody-dependent cellular cytotoxicity (ADCC) assay. They were poor proliferative responders to antigens and mitogens though the HTLV II lines did respond to interleukin 2 (IL2). The HTLV I lines were either nonresponsive to or were suppressed by IL2. Early passages of two of the lines produced IL2 but this was lost as the cells were passed in culture. The cell lines were capable of either directly or indirectly suppressing pokeweed mitogen (PWM)-driven immunoglobulin production by normal B cells. In addition, the lines were capable of producing gamma-interferon (IFN-gamma), lymphotoxin (LT), an interleukin 1 (IL1)-like factor, glial growth promoting factor (GGPF), and IL6. The advantage of these lines over clones or cell lines developed using other techniques is their growth in the absence of feeder layers or IL2 and their ability to be cloned and to grow in culture indefinitely.

Comparison of intrauterine and subcutaneous sites of estrogen injection for luteal maintenance in swine.

Intrauterine and subcutaneous sites for estradiol benzoate (EB) injection were compared in 30 gilts to test their relative effectiveness for estrogen-induced maintenance of corpora lutea. Vehicle or EB was injected on d 10 through 14 of the estrous cycle and corpora lutea that were maintained through d 24 were regressed subsequently by exogenous prostaglandin F2 alpha (10 mg). Cycle length (days) was not altered in either subcutaneous (18.6 +/- .5) or intrauterine (19.8 +/- .8) control groups. Gilts receiving 10 mg EB/d sc had longer (P less than .05) cycles (28.6 +/- 2 d) than gilts treated with 100 micrograms EB at either the sc (24.2 +/- 1 d) or intrauterine sites (23.3 +/- 1.3 d). The latter two cycle lengths were longer (P less than .05) than control cycles, but not different from each other. Before d 24, progesterone concentrations (ng/ml serum) were greater (P less than .01) in EB-treated gilts (25.1 +/- 2.0) than in controls (13.0 +/- 2.7). Progesterone concentration patterns were similar between gilts treated at intrauterine or sc sites. Thus, EB-induced maintenance of corpora lutea was not enhanced by direct injection into the uterine lumen.

Local immunity to Bacteroides gingivalis in periodontal disease.

The histopathologic status of gingival tissue was assessed according to the criteria of Page and Schroeder.(5) Rhodamine-labeled bacteria were used to assess the antigenic specificity of plasma cells in the tissue. Examination of tissue sections revealed that 31.6% of plasma cells in the advanced lesions bound the labeled bacterium, compared with only 3.1% of the cells in the early lesions. These results indicate that local immunity to Bacteroides gingivalis in greater in the more advanced than in the earlier forms of periodontal disease.

Determination of the specificity of plasma cells for bacterial antigens in situ.

We developed a method for determining the specificity of plasma cells for bacterial antigens in situ. The method consists of applying rhodamine-labeled whole bacteria to frozen sections of tissue in which inflammation had been induced by injection of the same bacterial strain. After appropriate washings, the tissue sections were briefly treated with a fluorescein-labeled antiserum to endogenous immunoglobulins to detect plasma cells. Plasma cells which could recognize bacterial somatic antigens appeared as clumps of orange-fluorescing bacteria overlying a green-fluorescing cell. The fidelity of the procedure was determined by performing several competition experiments, which showed that pretreatment of the inflamed tissue sections with homologous unlabeled bacteria (i.e., the same bacteria used to induce the tissue inflammation) decreased binding of the labeled bacteria to a significant extent. Pretreatment of the inflamed tissue sections with heterologous unlabeled bacteria, however, did not significantly decrease binding of the labeled bacterium. Additionally, binding of rhodamine-labeled heterologous bacteria to the tissue sections was insignificant. In further experiments, we demonstrated that there was no natural affinity between the bacterial strains employed and lymphocytes taken from the strain of rabbit used and that pretreatment of the sections with anti-immunoglobulin abrogated the binding of the bacteria to which the animal had been specifically sensitized.