Benchmarking in home care.

Recognizing that continuous quality improvement will be imperative for success in the future, six visiting nurse associations of northwestern Pennsylvania used benchmarking as a tool to improve their respective agencies' performance. The agencies benchmarked three areas: continuity of care, patient rehospitalization, and nosocomial infection rate.

Identification of anti-CD3 antibodies that do not modulate antigen but induce mitogenesis and block the mixed lymphocyte reaction.

Using a panel of anti-CD3-TCR monoclonal antibodies (OKT3 A-E), it appears possible to separate the ability to cause surface antigen modulation from inhibition of MLR or induction of mitosis. OKT3D, an antibody that recognizes the CD3 antigen at a site that can be differentiated from the epitopes recognized by other members of this panel by competition binding, does not cause antigen modulation when incubated with human T cells for up to 3 days. Despite this, OKT3D is mitogenic and is capable of blocking MLR. Two different isotypes were produced from the OKT3D clone, IgG1 and IgG2b. The IgG2b isotype of OKT3D blocked MLR even in individuals unable to respond mitogenically to this antibody. Use of members of this panel may now permit dissection of the types of signals delivered by the CD3-TCR complex inducing mitosis, receptor modulation, and other T-cell responses.

Early events in lymphocyte activation as defined by three new monoclonal antibodies.

Three new lymphocyte activation antigens are described whose kinetics of appearance place them very early in the activation pathway. The 78,000 dalton early antigen (Ea) 1 is present at low levels on resting lymphocytes, and its expression is enhanced twofold to threefold within 3 hr of stimulation. Ea2, a nondisulfide-bonded 86,000 and 73,000 dalton heterodimer, is first detectable 3 hr after activation and peaks by 9 hr. Its presence on all but a few cell lines, plus the variable association with a lower m.w. (28,000) structure, suggest that it may serve as a receptor for a growth factor. Neither Ea1 nor Ea2 are restricted to lymphocytes. The 31,000 dalton Ea3 antigen is induced only by PHA but not by other means of activation, and may pre-exist within the cell. The Ea3 antibody blocks PHA-induced but not OKT3-induced mitogenesis, suggesting differences in the pathways of activation by these two stimuli. These reagents, and OKT3, were used to define the cyclosporine A (CSA)-sensitive stage of lymphocyte activation. CSA blocks at a point before the biosynthesis of Ea1 and after that of T3/T cell receptor loss from the cell surface, at a point close to Ea2 biosynthesis.

A leukocyte subset bearing HLA-DR antigens is responsible for in vitro alpha interferon production in response to viruses.

In this report, we characterize the major human peripheral blood nonadherent mononuclear cell subset that is responsible for the production in vitro of alpha-interferon (alpha IFN) in response to influenza, Sendai, and Newcastle disease viruses. Using a panel of anti-monocyte, anti-B, anti-T and anti-natural killer cell monoclonal antibodies to purify and recover both positive and negative cell populations, we show that the major alpha IFN-producing cells are HLA-DR(+) cells with no other surface markers characteristic of either lymphocytes or myelomonocytic cells. These cells copurify, on Percoll density gradients, with cells mediating NK activity, but the cell population responsible for alpha IFN production can be distinguished unambiguously from NK cells based on the former's reactivity with an anti-HLA-DR monoclonal antibody, the lack of reactivity with antibodies that detect the low-affinity receptor for IgG on human natural killer cells and granulocytes, and the inability to mediate spontaneous cytotoxicity. Double immunofluorescence assays indicate that cells of this subset, the lineage of which is as yet undetermined but which might be related to dendritic cells, constitute a minor proportion (approximately 1-1.5%) of the nonadherent mononuclear cells from healthy donors.

Immune interferon and leukocyte-conditioned medium induce normal and leukemic myeloid cells to differentiate along the monocytic pathway.

Conditioned medium from phytohemagglutinin-stimulated human leukocytes contains a factor that can induce promyelocytic cell lines and certain acute myelogenous leukemia cells to differentiate along the monocytic pathway. In this report, we show that immature myeloid cells from normal bone marrow or the peripheral blood of patients with chronic myelogenous leukemia can be induced to differentiate to monocyte-like cells by immune gamma interferon (IFN gamma). We have identified IFN gamma as the predominant differentiation factor contained in the conditioned medium. Purified or recombinant IFN gamma, but not various preparations of IFN alpha or beta, can induce monocytic differentiation in myeloid cells. In cultures containing conditioned medium, the cells fail to continue myeloid maturation, and are induced to express monocyte markers and functions, such as monocyte-specific surface antigens, HLA-DR antigens, Fc receptors for monomeric immunoglobulins, nonspecific esterase, and the ability to mediate antibody-dependent, cell-mediated cytotoxicity. Even myeloid cells as mature as metamyelocytes or band cells can be induced by IFN gamma to undergo monocyte differentiation, but monocyte-specific or HLA-DR antigens are not induced in mature neutrophils. These findings reveal a previously unknown, specific function of human IFN gamma and offer new insights to the regulation of monocyte recruitment and differentiation during a virus infection or immune response.

Immune interferon induces the receptor for monomeric IgG1 on human monocytic and myeloid cells.

We report here that FcR for human monomeric IgG1 can be induced on cells of myeloid origin cultured in the presence of IFN gamma for 8 h. Supernatant fluids from cultures of lymphocytes infected with a variety of viruses or cocultured with cell lines have the same FcR enhancing effect as IFN gamma. We identify the factor in the supernatant fluid responsible for the induction as immune interferon. Among the different types of IFN, only the gamma type (both purified and recombinant) specifically induces the appearance of FcR for monomeric IgG1 on normal and leukemic myeloid cells but not on cells of lymphoid origin. This effect is also evident on mature PMN. We show that the specificity and the affinity of the receptor induced on HL-60 promyelocytic cells, peripheral blood monocytes, and PMN are identical to those of the receptor spontaneously present on the same cells, except for PMN, which do not spontaneously express this type of receptor. The results of inhibition experiments performed with mouse IgG of and IgG3. These results suggest that the receptor present on human monocytes different isotypes indicate that the receptor can be inhibited by murine IgG2a or immature myeloid cells, selectively inducible by IFN gamma, has a specificity similar to the FcR1 described on mouse macrophages.

A human NK and K cell subset shares with cytotoxic T cells expression of the antigen recognized by antibody OKT8.

The antigen recognized by monoclonal antibody OKT8 is expressed on the cell membrane of 30 to 50% of human NK/K cells. The reactivity of OKT8 with NK/K cells was determined by indirect methods (treatment of the effector cells with OKT8 antibody and complement (C) and separation of OKT8(+) and (-) effector cell populations by fluorescence-activated cell sorting or by rosetting techniques) and, at single cell level, by C-dependent lysis of effector NK cells that bind and kill K562 targets. Analysis by indirect immunofluorescence (flow cytofluorometry) of lymphocyte subpopulations mediating NK/K cytotoxic activity and deprived of OKT8(+) T cells reveals that the NK/K cell subset bears OKT8 antigen at a density lower than that present on cytotoxic T cells. The OKT8 antigen on NK/K cells is trypsin- and pronase-sensitive, but it is resynthesized by the same effector cells during 24 hr of culture at 37 degrees C. OKT8 antibody does not inhibit NK killing, and, on a per cell basis, OKT8(+) cells within the NK/K subset mediate the same level of cytotoxic activity as OKT8(-) NK/K cells. Analogous results were obtained by using anti-Leu-2a, an antibody with the same specificity as OKT8 on cytotoxic/suppressor T cells, but not when OKT5 was used, which might identify a distinct epitope on the same antigenic molecule. The possible significance of these findings in understanding the cell lineage of NK/K cells is discussed.

Human natural killer cells analyzed by B73.1, a monoclonal antibody blocking Fc receptor functions. II. Studies of B73.1 antibody-antigen interaction on the lymphocyte membrane.

In this paper, we characterize the antigen recognized by the monoclonal antibody B73.1 and the modification occurring at the membrane of the positive cells after interaction with the antibody. The B73.1-defined antigen is a protein of 50,000 to 72,000 daltons that is sensitive to pronase but not to trypsin treatment. B73.1 antibody, and its F(ab')2 fragment, directly block, at high concentrations, the binding of IgG antibody-sensitized erythrocytes to the Fc receptors (FcR) of a subpopulation of lymphocytes and neutrophils. B73.1 antibody dissociates rapidly from the positive cells, but concomitant modulation of both B73.1 antigen and FcR is induced when cells are incubated in the continuous presence of antibody or when B73.1 antibody is cross-linked at the cell membrane with an anti-mouse immunoglobulin antiserum. Reaction of lymphocytes with immune complexes also induces modulation of both FcR and B73.1 antigen, without affecting the expression of other antigens on the positive cells. The possibility that the antigen is internalized and digested by the cell after reaction with the antibody is discussed. B73.1 antibody inhibits antibody-dependent cytotoxicity mediated by lymphocytes (K cells) and neutrophils, whereas it does not affect spontaneous cytotoxicity of NK cells. These results suggest the B73.1-defined antigen might be the FcR or a structure closely related to it on K/NK cells.

Human natural killer cells analyzed by B73.1, a monoclonal antibody blocking Fc receptor functions. I. Characterization of the lymphocyte subset reactive with B73.1.

We describe the production of the monoclonal antibody B73.1, reacting with a subset of human lymphocytes and, in about one-half of the donors, with neutrophilic polymorphonuclear leukocytes. In the peripheral blood from normal adult donors, 14.6 +/- 8.5% of the lymphocytes react with B73.1 antibody. The B73.1(+) lymphocyte subset does not bear markers of typical T or B cells and corresponds to the lymphocyte subset containing antibody-dependent killer (K) and natural killer (NK) cells. We demonstrate that: a) virtually all lymphocytes with K/NK cytotoxic activity are found in the lymphocyte subpopulation bearing the B73.1-defined antigen; b) the B73.1(+) lymphocyte subset bears the combination of antigens known to be present on K/NK cells; and c) there is a positive correlation between the level of cytotoxicity and the actual number of B73.1(+) lymphocytes in individual donors. We also report the distribution of B73.1(+) lymphocytes according to donor age and tissue types. The use of the B73.1 antibody in quantitating the actual number of K/NK cells and in performing functional studies on spontaneous cytotoxicity is discussed.