Inhibition of HIV replication by liposomal encapsulated amphotericin B

This report shows the potential of using a liposomal encapsulated preparation of amphotericin B (a polyene macrolide antibiotic) for the in vitro inhibition of HIV. There was no significant difference between the effective doses of the free form of drug when compared to the liposomal encapsulated preparation in inhibiting the growth of HIV. Virus expression was suppressed at a concentration of 5-10 micrograms/ml of the drugs. The liposomal preparation showed greatly reduced cytotoxicity in experiments using cultures of murine leukocytes. These results show the potential usefulness of liposomal encapsulated drugs in the treatment of patients with AIDS or AIDS related complex.

Evidence for an additional temporal class of gene expression in the forespore compartment of sporulating Bacillus subtilis

We present evidence indicating that the previously studied, sporulation-induced gene 0.3 kb, which encodes a stable RNA present at late developmental stages, is transcribed in the forespore chamber of sporulating cells of Bacillus subtilis. Compartmentalized gene expression was demonstrated on the basis of subcellular fractionation experiments in which severalfold-higher levels of 0.3 kb-directed beta-galactosidase specific activity were observed in forespore extracts than in extracts from the mother cell and dependence studies in which 0.3 kb transcription was found to be blocked in mutants bearing mutations in spoIIIA, spoIIIE, and spoIIIG, genes which are known to govern forespore gene expression. Also, 0.3 kb transcription could be switched on during growth in cells in which transcription of the forespore regulatory gene spoIIIG was engineered to be activated in response to the lac inducer IPTG (isopropyl-beta-D-thiogalactopyranoside). Although it is transcribed in the forespore, 0.3 kb is switched on at a later developmental stage than other previously studied forespore-expressed genes, and hence it appears to be representative of an additional temporal class of compartmentalized gene expression.

Conservation of the D-mannose-adhesion protein among type 1 fimbriated members of the family Enterobacteriaceae

A variety of genera and species of the family Enterobacteriaceae bear surface fimbriae that enable them to bind to D-mannose residues on eukaryotic cells. Until recently, it was thought that the D-mannose binding site was located in the major structural subunit (FimA), of relative molecular mass (Mr) 17,000 (17 K), of these organelles in Escherichia coli. New evidence indicates that this binding site resides instead in a minor protein Mr 28-31 K (FimH) located at the tips and at long intervals along the length of the fimbriae, and is reminiscent of the minor tip adhesion proteins of pyelonephritis-associated pili (Pap) and S fimbriae. In contrast to the antigenic heterogeneity of the major FimA subunit, the antigenic structure of FimH is conserved among different strains of E. coli. Here, we report an even broader conservation of this minor adhesion protein extending to other genera and species of type 1 fimbriated Enterobacteriaceae. Our results may have implications for the development of broadly protective vaccines against Gram-negative bacillary infections in animals and perhaps in man.

Regulatory circuits in autoimmunity: recruitment of counter-regulatory CD8+ T cells by encephalitogenic CD4+ T line cells

In this study, pretreatment of Lewis rats with a syngeneic encephalitogenic T cell line (S1) was found to be able to constantly induce resistance to the subsequent induction of transferred experimental autoimmune encephalomyelitis (tEAE). This treatment was capable of protecting recipient animals for at least 2-4 months. Here we show an enhanced suppressor T(anti-S1) cell activity, which can be readily detected in the lymphoid organs of animals which recovered from S1-induced tEAE, or from rats pretreated with attenuated (irradiated, fixative treated or water-lysed) S1 cells. Anti-S1 cells, which uniformly express the CD8 phenotype, were selectively stimulated to grow and expand into lines by confronting primed lymphoid cells with irradiated S1 cells in culture. The proliferative response of anti-S1 cells was independent of myelin basic protein and antigen-presenting cells, and the responses against unrelated encephalitogenic T cell lines were minimal. It was also found that none of the monoclonal antibodies tested (including CD8 and MHC class I antigen-specific antibodies) was able to block S1/anti-S1 interactions. These cells are functionally suppressive to the proliferation of S1 cells in vitro, are specifically cytolytic directed against the EAE-inducing S1 cells and are able to antagonize encephalitogenic capacity of S1 cells in vivo. In vivo elimination of the CD8+ T subset from Lewis rats, using a combined treatment of thymectomy and OX-8 antibody injection before the initial cell transfer, totally blocked the induction of resistance. Our experiments document that induction of functionally active suppressor T cells is responsible for the induced resistance observed in tEAE.

Berberine sulfate blocks adherence of Streptococcus pyogenes to epithelial cells, fibronectin, and hexadecane

Berberine sulfate is an alkaloid extracted from the roots and bark of various plants and possesses antibacterial, antifungal, and antiprotozoal activities. Most studies have focused on the bacteriostatic or bactericidal activities of this compound. In this study, we report that berberine sulfate is bacteriostatic for streptococci and that sub-MICs of berberine blocked the adherence of streptococci to host cells, immobilized fibronectin, and hexadecane. Concentrations of berberine below its MIC caused an eightfold increase in release of lipoteichoic acid from the streptococci. Higher concentrations of berberine directly interfered with the adherence of streptococci to host cells either by preventing the complexing of lipoteichoic acid with fibronectin or by dissolution of such complexes once they were formed. Thus, berberine sulfate interferes with the adherence of group A streptococci by two distinct mechanisms: one by releasing the adhesin lipoteichoic acid from the streptococcal cell surface and another by directly preventing or dissolving lipoteichoic acid-fibronectin complexes.

Inhibition of human immunodeficiency virus replication by antisense oligodeoxynucleotides

Twenty different target sites within human immunodeficiency virus (HIV) RNA were selected for studies of inhibition of HIV replication by antisense oligonucleotides. Target sites were selected based on their potential capacity to block recognition functions during viral replication. Antisense oligomers complementary to sites within or near the sequence repeated at the ends of retrovirus RNA (R region) and to certain splice sites were most effective. The effect of antisense oligomer length on inhibiting virus replication was also investigated, and preliminary toxicity studies in mice show that these compounds are toxic only at high levels. The results indicate potential usefulness for these oligomers in the treatment of patients with acquired immunodeficiency syndrome (AIDS) and AIDS-related complex either alone or in combination with other drugs.

Influence of berberine sulfate on synthesis and expression of Pap fimbrial adhesin in uropathogenic Escherichia coli

We investigated the influence of berberine sulfate, an ancient Chinese antibiotic, upon the adhesion of uropathogenic Escherichia coli to erythrocytes and epithelial cells. Although berberine sulfate in increasing concentrations had no effect on bacterial growth or on the synthesis of major outer membrane proteins of the E. coli organisms, it increasingly blocked adhesion. The decreased adhesion was accompanied by a reduction in the synthesis of fimbrial subunits and in the expression of assembled fimbriae. These results suggest that the anti-infectious activity of berberine sulfate in E. coli-induced urinary tract infections may be mediated by the selective suppression of the synthesis and assembly of fimbriae by uropathogenic organisms.

A Mobile Oocyte Incubation Unit (MOIU): a device for improvement of the gamete intrafallopian transfer (GIFT) program

Forty couples with infertility due to various causes were selected for the gamete intrafallopian transfer (GIFT) program at our hospital. When the first 21 couples (Group A) had been treated in the program, the rate of pregnancy achieved was 23.8%, which did not seem satisfactory. This might have been caused by the distance between the embryo laboratory and the operating room. To eliminate this defect, a Mobile Oocyte Incubation Unit (MOIU) was designed. This is actually a compact laboratory that can be placed in the operating room. After the MOIU was utilized, the rate of pregnancy for the following 19 couples (Group B) increased to 42.1%. The MOIU has helped improve the performance of the GIFT program by increasing the stability of the pH value of the culture medium (Chetkowski R, et al.: J Vitro Fert Embryo Transfer 1985;2:207), lessening the exposure of the gametes to air and room temperature, and most importantly, shortening the time required for a GIFT procedure from 45-100 to 15-30 min. We expect that the MOIU will eventually become an integral part of the standard equipment for the GIFT program and make the program more successful and reliable in the treatment of infertility.

Dual biological activity of apurinic acid on human lymphocytes: induction of interferon-gamma and protection from human immunodeficiency virus infection in vitro

The chemically modified DNA, apurinic acid (APA), is cytotoxic for human lymphocytes at concentrations above 100 micrograms/ml. At low concentrations (0.05-1 micrograms/ml) APA acts as an inducer interferon gamma (IFN-gamma) in lymphocytes in vitro; the maximum interferon titer of 50 units/ml was reached at 0.4 micrograms/ml. When added to the cells in combination with phytohemagglutinin A (PHA), APA displays a significant synergistic interferon-inducing ability; the maximum titer of 940 units/ml was obtained with 10 micrograms/ml of APA and 6.25 micrograms/ml of PHA. APA also proved to be an effective inhibitor of human immunodeficiency virus (HIV-1) replication in H9 cells. At a concentration of 10 micrograms/ml, APA causes a 49% inhibition of virus growth, while 20 micrograms/ml of APA are required to inhibit expression of HIV-1 p17 and p24 gag proteins by 60%. The mechanism of anti HIV-1 activity of APA likely occurs at the level of viral reverse transcriptase. This enzyme is inhibited by APA in a noncompetitive way with a Ki of 0.39 microM, while the cellular DNA polymerases alpha, beta and gamma are 140- to 300-fold less sensitive to APA.

Scintillation counting of 14C-labeled soluble and insoluble compounds in plant tissue

A method is described for the liquid scintillation counting of 14C in plant tissues. Samples are fixed, in the scintillation vial, in a solution of ethanol and acetic acid (3:1) and decolorized with commercial bleach before the addition of scintillation liquid. The method was compared to other techniques of tissue oxidation or digestion and found to be equally effective at least with thin tissue samples. The technique is simple, rapid, and inexpensive and does not result in loss of 14C.

[Postoperative radiation of retinoblastoma--report on 22 patients]

From July 1958 to December 1979, 22 patients with retinoblastoma were treated postoperatively by radiotherapy. All were proved by pathology. There were 12 stage I, 1 stage II, 8 stage III and 1 stage IV lesions. Radiation dose was more than 15 Gy and most of the patients received 40-50 Gy in 4-5 weeks. The overall cancer free 5 year survival rate was 55% (12/22). The 5 year survival rate of stage I patients was 75% (9/12), and that of stage III patients was 38% (3/8). None of the stage II and IV patients survived. Dose of 40-50 Gy/4-5 wk is considered to be optimal for control of the tumor. Dose higher than 60 Gy/6 wk could lead to retarded growth in the orbital and temporal bony structures if the patient survives for ten years or more.

Identification of two ancillary subunits of Escherichia coli type 1 fimbriae by using antibodies against synthetic oligopeptides of fim gene products

We have chemically synthesized oligopeptides corresponding to the NH2-terminal stretch of two gene products, designated FimG and FimH, of the fim gene cluster of Escherichia coli. These synthetic peptides, designated S-T1FimG(1-16) and S-T1FimH(1-25)C, evoked antibodies in rabbits that reacted with 14- and 29-kilodalton subunits, respectively, of dissociated fimbriae encoded by the recombinant plasmid pSH2 carrying the genetic information for the synthesis and expression of functional type 1 fimbriae. Neither of these fimbrial proteins was detected in dissociated fimbrial preparations from nonadhesive E. coli cells carrying the mutant plasmid pUT2002, containing a restriction site-specific deletion of fimG and fimH. Anti-S-T1FimH(1-25)C inhibited the adherence of type 1 fimbriated E. coli to epithelial cells. Immunoelectron microscopy revealed that anti-S-T1FimH(1-25)C, but not anti-S-T1FimG(1-16), bound to intact type 1 fimbriae of E. coli at the fimbrial tips and at long intervals along the fimbrial filaments. Anti-S-T1FimG(1-16) appeared to be directed at epitopes not accessible on the intact fimbriae and consequently failed to bind to intact fimbriae or to block fimbrial attachment. Our results suggest that the fimG and fimH gene products are components of type 1 fimbriae and that FimH may be the tip adhesin mediating the binding of type 1 fimbriated E. coli to D-mannose residues on mucosal surfaces.

Value of postoperative radiotherapy for thyroid cancer

A series of 405 patients with thyroid cancer treated by surgery with or without postoperative radiotherapy from February 1958 through 1979 is reported. The immediate evaluation of the operation was that it was either incomplete or complete. Incomplete surgery implied that there was (1) possible residual tumor in the operative field, the result of difficult dissection of the tumor off the neighboring organs or tissues, as assessed by the surgeon; (2) multiple (more than five) lymph nodes involved; (3) positive border of the removed lesions; or (4) microscopic evidence of tumor in the operative field. Complete surgery implied through extirpation of cancer grossly and microscopically. In 297 patients who had complete surgery, 238 patients treated by surgery alone had a 5-year survival rate of 92% (218/238), while 59 patients who received postoperative radiotherapy had a 5-year survival rate of 78% (46/59). The optimum dose of postoperative radiotherapy was 50-70 Gy in 5 to 8 weeks, with the spinal dose kept under 40 Gy. Our experience shows that postoperative radiotherapy did not improve the survival of patients who had had complete surgery. Yet, in 108 patients who had incomplete surgery, surgery alone yielded a 5-year survival rate of 33% (19/57), while surgery plus radiotherapy yielded a 5-year survival of 71% (36/51). Our observation shows a remarkable benefit with postoperative radiotherapy in patients who have had incomplete surgery (P less than 0.05). According to pathologic criteria, postoperative radiotherapy was more effective in well-differentiated cancers than in poorly differentiated ones. It was equally effective in untreated as well as recurrent lesions. The prognosis for younger patients was better, but the sex of the patients did not affect prognosis.

Immune reactivity in the nervous system: modulation of T-lymphocyte activation by glial cells

The vertebrate central nervous system (CNS) has been traditionally thought to be inaccessible for the passenger lymphocytes of the immune system. This does not seem to be the case: activated T-lymphocytes can readily cross the endothelial blood-brain barrier (BBB) and some glial cells, notably the astrocytes, seem to be programmed to act as most efficient and complex partners for antigen-specific T-lymphocytes. We used myelin basic protein (MBP) specific permanent rat T-lymphocyte lines as probes to assess the immune status of the CNS. These cells, upon activation in vitro, are able to transfer lethal, experimentally induced autoimmune-encephalomyelitis (EAE) to normal syngeneic recipients. Activated T-lymphocytes, but not resting ones, can break through the BBB irrespective of their antigen specificity. Immune surveillance of the CNS thus seems to be executed by activated T-lymphocytes. Having crossed the BBB, the activated T-cells interact with local glial cells by releasing factors, including interferon-gamma, which induced astrocytes to synthesize and express, on their membranes, class II major histocompatibility antigens (Ia determinants), which are critically required for immunogenic presentation of antigens to T-cells. Indeed, Ia-induced astrocytes of the CNS (and the Schwann cells of peripheral nerves) are efficient antigen presenter cells, which are able strongly to up-regulate antigen-reactive T-lymphocytes. In addition, it has recently been shown that at least some astrocytes are able to down-regulate immune cells. Some, but not all, astrocytes are capable of suppressing activation of T-cells. This suppression can be modulated by interferon-gamma, and is sensitive to irradiation. The question of whether suppression is mediated by direct cell-to-cell contact or via soluble mediators (e.g. apolipoprotein E) is under investigation. Astrocytes have been found to be most subtle regulators of immuno-competent T-cells. Most probably they are centrally involved in physiological immune reactivity of the CNS, and it will be tempting to learn how far glial cells are involved in transmitting regulatory signals between the immune and nervous systems.

Synthesis and cell surface display of class II determinants by long-term propagated rat T line cells

We have investigated the capacity of the encephalitogenic BS rat T cell line bs 83 and its variant clone bs 83.III.C6 to synthesize and express RT1.B-specific class II molecule subsets defined by monoclonal antibodies (mAb) MRC-OX6 and MRC-OX3. Earlier studies had indicated that mAb MRC-OX6 recognizes three distinct molecular species: an immature oligomeric polypeptide chain complex comprised of the polymorphic subunits alpha, beta and the invariant proteins of the gamma group; a biosynthetic intermediate composed of post-translationally modified alpha, beta and gamma chain (denoted p35) and a fully glycosylated alpha, beta two-chain complex derived from the plasma membrane. MRC-OX3 was shown to recognize a serologically distinct alpha, beta two-chain complex that coexists with the MRC-OX6-specific heterodimer at the cell surface. Here we show that premutant bs 83 cells were unable to synthesize class II molecules of either set. In contrast endogeneous synthesis by mutant cells of MRC-OX6-specific molecules was demonstrated. Unlike control spleen cells variant cells failed to synthesize the mature MRC-OX3-reactive class II subset. Instead a three-polypeptide chain complex comprised of the terminally glycosylated subunits alpha, beta and invariant chain p35 was present at the cell surface. This complex appears to represent the preserved biosynthetic intermediate that failed to release invariant chain p35 upon its transit into the plasma membrane. These latter observations support our notion of gamma chain-induced epitope diversification during post-translational maturation of RT1.B-specific class II molecules.

Inhibition of replication of the etiologic agent of acquired immune deficiency syndrome (human T-lymphotropic retrovirus/lymphadenopathy-associated virus) by avarol and avarone

Avarol and avarone are two antimitotic and antimutagenic agents that preferentially inhibit proliferation of T-cell leukemia lines in vitro. This report shows that these compounds have a dose-dependent inhibitory effect on the replication of the etiologic agent of acquired immune deficiency syndrome (AIDS), human T-lymphotropic retrovirus (HTLV-III)/lymphadenopathy-associated virus, in human H9 cells in vitro. Both compounds show a significant cytoprotective effect on HTLV-IIIB-infected H9 cells at concentrations as low as 0.1 microgram/ml (0.3 microM). Both avarone and avarol block in a dose-dependent manner the expression of the p24 and p17 gag proteins of HTLV-III in H9 cells after virus infection and block viral replication, as judged by approximately 80% inhibition of reverse transcriptase activity. These results strongly suggest that these compounds may prove to be useful in the treatment of patients with AIDS and AIDS-related complex.

Calmodulin: localization in plant tissues

Calmodulin was purified from bovine brain by preparative SDS-polyacrylamide gel electrophoresis. The denatured, purified calmodulin was used to immunize rabbits to produce antiserum. This antiserum was used to study the distribution of calmodulin in plant tissues by indirect immunohistochemistry. The root tips from corn seeds, oat seeds, peanuts, spaghetti squash seeds, and the terminal buds of spinach were investigated. A method for plant tissue sectioning and inhibition of endogenous peroxide activity was developed. In the corn root section, reaction product from anti-calmodulin was found mainly in the root cap cells. Lesser but significant amounts of calmodulin were localized in metaxylem elements, in some stele cells surrounding metaxylem elements, in apical initials, and in the cortical cells. Similar findings were also observed in other root tips from oat seeds, peanuts, and spaghetti squash seeds. In the terminal buds of the spinach, calmodulin-stained cells were highly concentrated in the apical meristem and leaf primordium. These findings suggest that the high concentration of calmodulin in the root cap may be important in relation to gravitropism and growth development.

Ia-restricted encephalitogenic T lymphocytes mediating EAE lyse autoantigen-presenting astrocytes

T lymphocytes specific for myelin basic protein (MBP) are responsible for the cellular events leading to autoimmune disease within the central (CNS) and peripheral (PNS) nervous systems. Both in actively induced and T-cell transfer versions of experimental autoimmune encephalomyelitis (EAE) and neuritis (EAN), the autoaggressive T cells are activated outside the nervous system and reach their target tissue via the blood circulation. The target specificity of the autoaggressive T cells is impressive; T-cell lines specific for MBP predominantly home to and affect the white matter of the CNS whereas T cells specific for PNS myelin protein P2 exclusively infiltrate peripheral nerves. Having penetrated the tight blood tissue barriers, the lymphocytes seem to interact with local cells expressing the relevant autoantigen in an immunogenic form. Although the exact mechanism of target finding and destruction is unknown, studies from our laboratory have shown that astrocytes, a main component of the normal CNS glia, can actively present antigen to specific T cells. This observation suggests that astrocytes are involved in natural immune reactivity within the CNS, and that they may be involved in pathological aberrations, such as in the development of autoimmune lesions. Having studied astrocyte/T-cell interactions in more detail, we discovered that encephalitogenic T-cell lines recognizing MBP on astrocytes will subsequently proceed to kill the presenting cells. Here we report that astrocyte killing follows the rules governing 'classical' T-cell-mediated cytolysis; it is antigen-specific, restricted by antigens of the major histocompatibility complex (MHC) and apparently contact-dependent. Our data suggest that the nature of the recognized antigenic epitope determines whether or not antigen recognition is followed by killing; moreover, killing of antigen-presenting astrocytes seems to be correlated with the capacity to transfer encephalomyelitis to normal syngeneic rats.

Clonal analysis of the population of chondrocytes from the Swarm rat chondrosarcoma in agarose culture

Chondrocytes from the Swarm chondrosarcoma, a transplantable rat tumor, have been difficult to maintain in tissue culture for extended periods due to a time-dependent alteration of the culture to a more fibroblastic phenotype. This feature precluded the use of these cultures to examine chronic conditions that may affect cell metabolism, and the homogeneity or heterogeneity of the tumor cells within the culture population could not be examined. Use of suspension culture in agarose stabilized the chondrocyte phenotype, permitting long-term culture. Clones of tumor chondrocytes were established in agarose and were examined over 2-3 weeks for evidence that the cells were accumulating a proteoglycan-rich extracellular matrix, as determined by positive staining by Alcian blue, and were undergoing cell division. Nearly 90% of the cloned cells exhibited a prominent extracellular matrix by day 7 of culture and greater than 99% did so by day 14. Cell division did not occur to any great extent until days 6-7 of culture. After this lag, the cells appeared to undergo logarithmic growth, with a cell generation time of about 12 days. By 20 days of culture, between 80 and 90% of the initial clones contained multiple cells, indicating that nearly all the cells were in, or had entered, the cell cycle. These results suggest that the chondrocytes from the rat chondrosarcoma form a homogeneous cell population with respect to their ability to synthesize an extra-cellular matrix and divide.

Suppressor mutations for crs mutants of Bacillus subtilis

Mutants of Bacillus subtilis which carried suppressor mutations for catabolite-resistance gene crsA47 were isolated from methylmethanesulfonate-treated cultures of GLU-47 (crsA47). The suppressor mutation, sca19, suppressed resistance of crsA47 mutant to glucose and other inhibitors of sporulation. Moreover, the suppressor mutation could restore the rate of growth and the level of IMP dehydrogenase and alkaline phosphatase of crsA47 mutant to the wild-type level. The scal19 mutation was also able to suppress catabolite resistance of other crs mutants. The map position of the sca19 mutation indicated that this mutation was an intergenic suppressor for the crs mutants. It was also found that an erythromycin-resistance mutation, eryl, could suppress the catabolite resistance of some of the crs mutants. Our results were discussed in relation to the importance of a proper state of metabolic activities and membrane functions during the initiation of sporulation.

Killer-cell lines derived from mouse thymus, resembling large granular lymphocytes and expressing natural killer-like cytotoxicity

Murine thymus cells were maintained in vitro with supernatant-factors derived from Concanavalin-A-stimulated spleen cells. After an initial phase of vigorous proliferation, large granular cells (GC), which were not observed in fresh thymus cell preparations, appeared in these cultures. GC, derived from C3Hf/Tif-, BALB/c-, and C57BL/10-thymus cultures, could be slowly expanded and have been maintained as increasingly homogeneous (oligoclonal) lines for up to six months. During this time, other types of thymus cells died or were diluted out. Thymic GC differ functionally and histochemically from macrophages and mast cells. They do not phagocytize zymosan particles, bind opsonized SRBC, express nonspecific esterases or contain detectable amounts of histamine. GC share many features with natural killer (NK) cells and large granular lymphocytes (LGL). One morphologically representative line (C3Hf/Tif) had the following surface phenotype: Thy-1+, Lyt-1-, Lyt-2-, H-2K+, I-A-, asialo Gm1+. GC bind peanut agglutinin (PNA) on their surface and contain azurophilic granules. These cytoplasmic granules are considerably larger than those in LGL. Cells of a GC line derived from mouse strain C3Hf/Tif (H-2k) lysed the NK-sensitive YAC-1 (H-2a) and EL-4 (H-2b), but not the NK-insensitive P815 cells.

Macrophages as cytotoxic effector cells

Cells of the mononuclear phagocyte system can be activated by lymphokines to both increased extracellular cytotoxicity against tumor targets and intracellular cytotoxicity against micro-organisms. In addition, these effector cells can kill antibody-coated target cells in an ADCC system. These two cytotoxic mechanisms can co-operate and act synergistically. Such an synergistic action is characterized by the specificity of the antibody which coats the target cells and not by the non-specific activation induced by high dosages of lymphokine. The lymphokine MCF has partially been purified and separated from a variety of other lymphokines. This purified material, when injected into mice intraperitoneally, activates the macrophages to strong cytotoxicity. Evidence obtained by the use of different rat anti-mouse macrophage monoclonal antibodies suggests that there exist different subpopulations of macrophage and that some of these subpopulations can be correlated to defined functions.

Functionally different subpopulations of mouse macrophages recognized by monoclonal antibodies

Four rat anti-mouse macrophage monoclonal antibodies are described. Three of them are highly specific for macrophages, and one cross-reacts with granulocytes. All 4 antibodies do not react with membrane antigens shared by all macrophages, but with antigens present only on subpopulations of 20-50% of the cells. All antibodies are directly or indirectly cytotoxic for macrophages. The subpopulations defined by these antibodies can be correlated with certain macrophage functions. Thus, antibody M 43 eliminates macrophages that are activated by lymphokine to cytotoxicity. Antibodies M 43 and M 57 eliminate macrophages that kill antibody-coated tumor targets, and clone 102 (strictly macrophage-specific) eliminates natural killer cells. Only M 143, reacting with 10-30% of macrophages, has not yet been correlated with any function. With the use of these antibodies, cells of the macrophage lineage with specific functions can be recognized and eliminated from a given population.