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Purpose: To compare the occurrence of red blood cell (RBC), platelet (PLT), and white blood cell (WBC) antibodies in preterm infants after transfusions., Methods: A randomized, blinded trial was conducted in which preterm infants were transfused either with stored RBCs, prepared by prestorage leukocyte reduction and transfused throughout 42 days of storage to limit donor exposure (n = 18), or with fresh RBCs prepared without leukocyte reduction and transfused within 7 days after collection from as many donors as needed to guarantee freshness (n = 17). Nontransfused preterm infants of comparable birth weight were control subjects (n = 11)., Results: No RBC antibodies were detected in serial blood samples taken during the first 6 months of life. Similarly, no definite WBC antibodies were found, although weak reactivity was detected transiently in sera from two infants. Accordingly, RBC and WBC antibody production did not differ among groups. In all, 11% of the transfused the infants exhibited platelet antibodies: 14% of the infants given stored leukocyte-reduced RBCs and 7% of the infants given fresh nonleukocyte-reduced RBCs (difference not statistically significant)., Conclusions: Preterm infants rarely produce antibodies to blood cell antigens after RBC transfusions, regardless of whether the exposure is to fresh unmodified RBCs from several donors or to stored leukocyte-reduced RBCs from a limited number of donors. Therefore, efforts to limit donor exposures or to remove WBCs from blood components cannot be justified simply for purposes of preventing alloimmunization in neonates.

We have discovered a previously unpublished HLA-DRB1 allele, observed in a patient (SB), his mother, and one sibling. The undefined allele gave sporadic positive reactions with sera in the DR52-associated group. SSOPH analysis utilizing both generic and group specific primers and probes also gave ambiguous results. SB typed clearly as a DRB1*0301 (paternal allele) but the DNA from SB also bound probes specific for DRB1*14 and DRB1*11. Sequencing revealed that the undefined allele was similar to a DRB1*14 allele with a segment of sequence found in DRB1*11 alleles. The patient was MLC reactive with donors who express DRB1*0301, *1401 and *0301, *11 and was nonreactive solely to DRB1*0301 (Dw3) homozygous typing cells.

Bw4 and BW6 epitopes are expressed by mutually exclusive sets of HLA-B alleles and some HLA-A and HLA-C alleles. To test whether antithetical structures are required to express Bw4 and Bw6 epitopes, we measured binding of Bw4-reactive and Bw6-reactive alloantibodies and mAbs to HLA-B7 variants. A triple substitution of HLA-B7 alpha-1 helix residues 80, 82, and 83 created Bw4 and destroyed Bw6 epitopes detected by alloantibodies and mAbs. Both Bw4-reactive and Bw6-reactive mAbs competed for binding to HLA-B7 variants with single substitutions at residues 82 and 83. Substitutions of residues H93 and D119 which form a salt bridge in HLA-A2 also permitted binding by both Bw4-reactive and Bw6-reactive mAbs, suggesting that Bw4 and Bw6 epitopes are conformationally dependent. Six Bw4-reactive mAbs showed four distinct patterns of binding to HLA-B7 variants. Detailed analysis of 74 HLA-B7 single-residue variants showed that Bw6-reactive SFR8-B6 binding was prohibited by mutations altering the distal end of the alpha-1 helix and the nearby connecting loop. In contrast, Bw6-reactive BB7.6 binding required both alpha-1 and alpha-2 helix residues. Thus, Bw4-reactive and Bw6-reactive Abs recognize multiple distinct HLA structures that partially overlap in the alpha-1 helix. As both Bw4 and Bw6 epitopes are expressed by some HLA-B7 variants, mutually exclusive expression of Bw4 and Bw6 epitopes in naturally occurring HLA class 1 molecules may reflect evolutionary pressure.

Purpose: To establish a human leukocyte antigen (HLA) association in a homogeneous population of patients with pars planitis., Methods: A strict set of inclusion parameters was established for the diagnosis of pars planitis. Forty patients with pars planitis who met these criteria underwent HLA analysis of class I and II phenotypes., Results: HLA-B8 was present in 15 (37.5%) of 40 patients versus 85 (19.7%) of 431 controls (relative risk, 2.44; P = 0.011). HLA-B51 was present in 9 (22.5%) of 40 patients versus 51 (11.8%) of 431 controls (relative risk, 2.16; P = 0.049). HLA-DR2 was present in 27 (67.5%) of 40 patients versus 121 (28.0%) of 431 controls (relative risk, 5.32; P < 0.0001). HLA-DR2 has been associated with multiple sclerosis (MS). Exclusion of five patients with pars planitis in whom MS subsequently developed did not change the significance of these findings., Conclusions: The strongest association of pars planitis with HLA-DR2 and the temporal development of MS in some patients with pars planitis further supports an association between pars planitis and MS.

To evaluate the relationship between human leukocyte antigen (HLA) and both asbestos-induced pulmonary fibrosis and pleural fibrosis, we obtained HLA-A, B, C, DQ, and DR phenotypes in 42 long-term asbestos-exposed workers. Among these exposed workers, 15 had asbestosis (ILO > or = 1/0) on the chest radiograph and 18 had asbestos-induced pleural fibrosis. We found that there was an increased percentage of HLA-A29, HLA-B44, and HLA-Bw4 in the subjects with asbestosis. In addition, we observed a marginally positive relationship between HLA-A29 and the severity of pulmonary fibrosis. Similarly, there was a higher prevalence of HLA-DRw53 and DQ2 in the subjects with asbestos-induced pleural fibrosis. The presence of HLA-DQ2 was significantly related to the extent and type of asbestos-induced pleural fibrosis while HLA-DRw53 was not consistently related to the type or extent of pleural disease. Importantly, we observed that HLA-A29, HLA-B44, HLA-Bw4, HLA-DRw53, and HLA-DQ2 do not have a significantly shorter duration or latency of asbestos exposure. Moreover, none of the HLA haplotypes (A29, B44, Bw4, DRw53, and DQ2) that we found to be associated with radiographic manifestations of asbestos-induced lung disease were associated with the physiologic abnormalities that have been traditionally associated with asbestos-induced lung disease. The only exception was an isolated decrease in the residual volume associated with the presence of HLA-A29. These results suggest that the HLA-A29 phenotype may be associated with the development of asbestosis and the HLA-DQ2 phenotype may be associated with the development of asbestos-induced pleural fibrosis. However, these associations are not particularly strong, physiologic correlation is lacking, and previous studies do not support our findings.

After a patient with a history of systemic lupus erythematosus in remission was given salsalate, all of her hematologic elements, especially leukocytes, profoundly decreased within hours, although the patient was receiving steroids. She had been challenged with salsalate at an earlier date, with a similar but less impressive drop in blood counts. Granulocytotoxic antibodies persisted during this episode in contrast to declining lymphocytotoxic and anti-native DNA antibodies that accompanied a remission of systemic lupus. This is the first case of this kind occurring with salsalate therapy and may have represented preformed antibodies induced by salsalate.

In a previous study, we identified glutamic acid at position 58 in DR (beta 1*1101) as critical for the epitopes recognized by the DRw11-specific mAb GS88.2, as well as the I-LR1 mAb that recognizes a polymorphic epitope on DR(alpha,beta 1*1101) and some DP molecules. The purpose of this study was to determine whether other polymorphic residues contribute to these epitopes and whether DR beta glutamic acid or alanine 58 and DP beta glutamic acid 56, the analogous position in DP beta, contribute to epitopes recognized by other anti-class-II mAb and allosera. Site-directed mutagenesis and transfection were used to produce cells bearing wild-type or mutant class II molecules that were analyzed with mAbs by flow cytometry and with human allosera by absorption and subsequent microcytotoxicity assays. These studies demonstrate that the residue at DR beta position 58 plays a central role in at least three different mAb epitopes and an epitope recognized by anti-DRw11 allosera. Substitution of glutamic acid for alanine at position 58 of eight DR beta chains caused gain of binding of four mAbs to all of the mutant molecules, except DR(alpha,beta 4*0101). These data suggest that the side chains of DR beta 58 and DP beta 56 point outward from the alpha-helix and directly contact antibody.

Premature neonates require blood transfusions, and biological parents may wish to be directed donors. Biological mothers pose a potential danger because their plasma may contain antibodies that will react with blood cell antigens inherited by the infant from the father. We studied 25 healthy, pregnant women at the time of delivery for the presence of antibodies against red blood cell, leukocyte and platelet antigens. Mothers known to have red cell antibodies earlier in pregnancy were excluded, and no new red cell antibodies appeared at delivery. Antileukocyte and antiplatelet antibodies were found in 16 and 12% of mothers, respectively. Because these antibodies have the potential to cause adverse reactions when transfused passively, we suggest that either biological mothers not provide blood components containing plasma for their neonates or that maternal red cells and platelets be given as washed products.

Acute posterior multifocal placoid pigment epitheliopathy is a chorioretinal inflammatory disease occurring in young, healthy adults. Its cause is unknown, although it frequently follows a flulike illness. We reexamined 30 patients with documented acute posterior multifocal placoid pigment epitheliopathy to determine their HLA class I antigen (A and B) and class II antigen (DR and DQ) distribution. The HLA class I antigen B7 was found in 12 patients (40.0%) compared with 63 controls (16.6%) (relative risk, 3.38). The class II antigen DR2 was present in 17 patients (56.7%) compared with 107 controls (28.2%) (relative risk, 3.34). The specific role of HLA antigens in uveitis is unknown, but the finding of an increased prevalence of HLA-B7 and HLA-DR2 antigens in patients with acute posterior multifocal placoid pigment epitheliopathy suggests an immunogenetic predisposition to acquiring this disease.

Human peripheral blood lymphocytes heated at 45 degrees C for 1 hr were found to continue to express all the serologically detected class II MHC antigens (HLA DR, MT, MB) but not to stimulate proliferation in primary or secondary MLR. Such cells did, however, stimulate the formation of potent suppressor cells. Three additional stimulator cell models for the presentation of either class I antigen only (purified platelets and purified T cells) or class I antigen plus nonimmunogenic class II antigen (D/DR-compatible cells) gave identical results. Supernatants from cultures stimulated with any of these cell types had significantly reduced IL 2 activity when compared to control MLR. The suppressor cells generated in such cultures were not restricted to the class I or class II MHC antigen of the original stimulator. These data are interpreted to mean that 1) the class II epitopes detected by alloantisera and the epitopes that serve as lymphocyte-activating determinants are metabolically or conformationally distinct, and 2) that presentation of class I MHC antigen alone or in conjunction with nonimmunogenic class II MHC antigen preferentially stimulates the formation of suppressor cells. It is hypothesized that the latter may be an additional mechanism that contributes to the efficacy of matching for class II determinants in human renal transplantation.

Unseparated human T cells or isolated OKT4+ and OKT8+ subsets were stimulated in allogeneic MLR and subsequently tested for their capacity to suppress fresh autologous responding cells in a second MLR. Contrary to the bulk of evidence regarding the immunoregulation of B-cell function, both OKT4+ and OKT8+ cells could be activated to form suppressors of the MLR and were equally radioresistant. An early peak of blastogenesis was observed when OKT4+ suppressors were used, and this event was completely radiosensitive. When the fresh responding cells were also fractionated into OKT4+ and OKT8+ subsets, no preference for suppressibility of either subset could be demonstrated, indicating that OKT4+ suppressors were acting directly and not through an inductive mechanism requiring OKT8+ effectors. It is suggested that when alloantigenic responses are involved, the human T-cell subsets defined by these monoclonal antibodies may be more accurately defined by the class of MHC antigen to which they respond than by their effector function.

Agranulocytosis developed in a patient who was receiving propylthiouracil. Using a microgranulocytotoxicity assay, serum taken from the patient was shown to be strongly granulocytotoxic when tested against the patients granulocytes and those obtained from two of eight normal subjects. Tests for granulocyte agglutinins and for lymphocytotoxicity were negative. Granulocytotoxic activity decreased as the patient's peripheral granulocyte count recovered. Cytotoxicity was shown to be mediated by a complement-dependent IgM antibody.

The role of secreted and membrane-bound IL-1 in the activation of human T cells by monocyte-associated, processed antigen was examined. The IL-1 is secreted from antigen-pulsed plastic-adherent monocytes for only 24 h after isolation. After extensive washing, however, these monocytes are fully capable of stimulating T cells to proliferate. The T cells require less than 24 h of exposure to the monocytes to become activated and can then be cultured alone in fresh media. Addition of exogenous IL-1 does not enhance T-cell responsiveness in this model. Anti-IL-1 beta antibody does not inhibit the response, although we observed that pulsed monocytes have significant membrane-bound IL-1 assayed as biologic activity in the murine thymocyte costimulator assay. These studies suggest that secreted IL-1 is not required for the activation of human T cells and that membrane-bound IL-1 serves this function. The data further suggest that these two forms of IL-1 may be functionally distinct and that IL-1 beta is not the major component of membrane-bound IL-1. The possible relationship of these findings to the clinical efficacy of IL-1 inhibitors, such as corticosteroids, is discussed.

DRw52 (formerly MT2) is a human Ia alloantigen that is expressed in linkage disequilibrium with DR3, 5, w6, and w8. Although there is general agreement that the DRw52 determinant resides on biochemically defined DR molecules, conflicting evidence exists regarding whether DRw52 resides on one or both DR molecules, DQ and DR molecules, or DR and BR molecules. Six anti-DRw52 allosera and three DRw52-like monoclonal antibodies were used to identify the Ia molecules that bear the DRw52 and DRw52-like determinants from DR5 and DRw6 homozygous cells. Based on these two-dimensional gel studies, the DRw52 allodeterminant appears to reside on a subset of DR molecules from DR5 and DRw6 cells. In contrast, the determinants defined by the three anti-DRw52-like monoclonal antibodies were found to reside on one DR molecule, on the second DR molecule, or on both DR molecules, respectively. Therefore, there is considerable complexity of Ia antigenic determinants that are associated with DR3, 5, w6, and w8 at the population level.

Human suppressor cells (SC) differing in both kinetic characteristics and degree of specificity were induced in vitro either by Concanavalin A (CON A) (10 microgram/ml) or by repeated stimulation with allogeneic cells. CON A SC caused a characteristic early peak in blastogenesis (Day 2) when cocultured with fresh autologous cells in the presence of either CON A or augmented response fell rapidly to values 50--90% below positive controls by the usual optimal day for the particular stimulus. Treatment with 5-bromodeoxyuridine and light during rapid proliferation ablated the early responses but increased the later responses (i.e., reduced the suppression). The cells mediating both the early rise and late suppression were found to belong to a subset of T cells that lost their ability to form SRBC rosettes (theophylline sensitive) in the presence of the phosphodiesterase inhibitor, theophylline, and were inactivated by mitomycin C. In contrast, SC induced by repeated allogenic stimulation were suppressive in MLC but not CON A cultures, did not initiate early blastogenesis in the presence of naive cells and were partially mitomycin resistant. The mitomycin resistant SC induced by allogeneic stimulation are found in the theophylline resistant T-cell subset. These data are consistent with a model of human SC differentiation in which at least two subsets may be present: (1) a mitomycin sensitive, nonspecific cell that participates in an obligatory early autologous recognition event (induction?) and (2) a later occurring, more mitomycin resistant effector cell that appears to acquire specificity for the response that it affects.

The hypothesis that alpha-fetoprotein (AFP) is immunosuppressive in vitro was tested with immunoabsorbent purified human cord AFP in human lymphocyte cultures. Albumins were purified identically from cord plasma and pooled adult plasma. No preparations were suppressive in phytohemagglutinin-stimulated cultures. Both AFP and human cord albumin (HCA) produced 50% suppression of allogeneic lymphocyte cultures at 50 to 100 microgram/ml final concentrations, whereas adult and commercial albumins were not suppressive. When AFP was eluted from the immunoabsorbent column in 0.15 M NaCl rather than the conventional 0.5 M NaCl, activity was greatly diminished or lost, but could be restored by dialysis against 0.5 M KCl. Previously, inactive lots of HCA also demonstrated the same phenomenon. It appears, therefore, that the immunosuppressive activity of AFP (and albumin) may depend both on its source and the procedure by which it is isolated. Whether analogous conditions occur in vivo is unknown at this time.

Although reactions to granulocyte transfusions in neonates are rarely reported, we observed a near-fatal pulmonary reaction, presumably due to white cell antibodies, in a neonate with Rh hemolytic disease. The hemolytic disease was being treated with exchange transfusions, and at 2 days after the infant's birth, bacterial sepsis was suspected and granulocyte transfusions were begun. The first granulocyte transfusion (Day 3) was uneventful. Five minutes after the beginning of the second granulocyte transfusion (Day 4), severe respiratory distress, hypotension, bradycardia, cyanosis, and acidosis suddenly occurred. The infant's serum obtained after the reaction contained granulocytotoxic and B-lymphocytotoxic antibodies that reacted with leukocytes from the second granulocyte donor. Antibodies could not be detected either in the initial infant serum or in maternal serum. However, an antileukocyte antibody was present in the serum of a parous woman donor. We used plasma from this woman to prepare reconstituted whole blood for the exchange transfusion that we performed immediately preceding the second granulocyte transfusion. Despite the sequence of events, an irrefutable cause-and-effect mechanism could not be established because the properties of the donor and neonatal antibodies were similar, but not identical. However, this catastrophic event emphasizes both the potential for adverse effects of granulocyte transfusions in neonates and the need for caution when transfusing blood from parous women.

Human memory cells acquire resistance to several types of suppressor cells, including MLR generated suppressor cells. These data suggest one possible mechanism of that resistance, namely retention of IL-2 receptors in the resting state. Cells from a 7-day MLR were separated on a single step percoll gradient. All proliferating cells were found in the interface. Pellet cells were nondividing. Interface and pellet cells had equivalent memory function in a secondary MLR. Thus, there appear to be at least two subpopulations of memory cells, including one that is primed without undergoing division. These subpopulations are functionally distinct. Interface memory cells were 30-50% more resistant than pellet memory cells to MLR generated suppressor cells. On culture day 10, neither pellet nor interface cells displayed significant spontaneous proliferation but exogenous Interleukin 2 (IL-2) produced up to five times as much proliferation in interface cells as in pellet cells. Further, FACS analysis with an anti-TAC equivalent antibody also showed that significantly more interface cells have surface receptors for IL-2. Thus, cells that had previously divided continue to have more and/or higher affinity receptors for IL-2 even after return to the resting state. If a mechanism of suppression in the mixed lymphocyte reaction is to reduce the synthesis/release of Il-2, memory cells may acquire their relative resistance to this suppression by virtue of the increased IL-2 sensitivity of this discrete subpopulation.

The relative sensitivity of the MLR responses of freshly isolated human lymphocytes to Con A-induced suppressor cells (SC) was compared to that of lymphocytes that had been primed previously in vitro. Fresh and primed cells were suppressed 72 and 17%, respectively, when cultured under similar conditions (p less than 0.0005). Titration of SC indicated that equivalent suppression in the two populations would require greater than a 50-fold excess of SC in the primed cells. Neither preincubation of the primed cells for 24 or 72 hr with the SC before restimulation, addition of fresh autologous cells to the primed cells, nor preincubation of the SC with fresh cells before addition to the primed cells increased suppression of primed cells. SC added at the beginning of a primary MLC were, however, very suppressive for both the primary response (67% suppression) and the subsequent secondary response (81% suppression). These data indicate that although the human primary MLR and the precursor of the memory cell are both sensitive to the suppressors induced by Con A, the memory cell itself possess an intrinsic resistance to such suppressors that is not related to simple kinetic phenomena nor to the loss in vitro of an intermediate regulatory cell. Cell depletion experiments suggest that resistance to nonspecific suppression may occur at the level of the helper cell.

The diminished response to secondary stimulation of human lymphocytes primed in bi-directional (BD) mixed lymphocyte culture (MLC) has been demonstrated to be due to cytotoxic destruction of the responder cells by the numerically superior allogeneic stimulating cell population. This phenomenon is called Functional Cell Mediated Lympholysis (F-CML). Matching for HLA-A and B, HLA-DR or for MLC non-responsiveness (HLA-D) in unrelated pairs does not ablate F-CML, indicating that none of these loci serve as the exclusive target for this activity. One locus appears to be centromeric from HLA-A in an A/B recombinant family and a B/D recombinant family demonstrates a target centromeric from HLA-B. A special family with homozygous for HLA-A, B and D provided evidence for an additional locus other than HLA-A, B or D. Thus, genetic studies indicate that at least one target antigen of F-CML may be coded for by a locus that is centromeric from HLA-B and which may be distinct from HLA-D or DR.

It is estimated that 60-70% of patients who might benefit from a bone marrow transplant will not have a suitably matched, related donor. We have, therefore, designed a clinical experiment to test the safety and feasibility of using marrow from partially matched, unrelated donors. This paper details our transplant experience in the first eight patients with leukemia. The first four patients had advanced leukemia at the time of transplantation. Each showed hematopoietic recovery, but all died from septic complications largely related to extended neutropenia encompassing both the pre-marrow-grafting and the post-marrow-grafting period. The next four patients were in remission at the time of transplantation. Each showed prompt and sustained hematopoiesis with variable graft-versus-host disease (GVHD). No acute or chronic GVHD was seen in two patients, grade II (skin only) was seen in one patient, and grade IV (skin, liver, and gut) was seen in one patient. One patient has died from sepsis five-and-one-half months following transplantation, and three are alive and well six-and-one-half to nine-and-one-half months postengraftment. This preliminary experience, together with several case reports in the literature, leads us to conclude that bone marrow transplantation with partially matched, unrelated marrow is a safe and feasible approach. If these results are confirmed by longer follow-up in a larger group of patients, the development of marrow donor pools would appear to be justified.

Cyclosporine is a potent new immunosuppressive agent utilized in clinical organ transplantation. Available evidence suggest that it interferes with the secretion of interleukin-2. However, the long term efficacy of cyclosporine in preventing allograft rejection may depend on a relative sparing of suppressor cells early in the allogeneic response, allowing them to mature and effect a state of operational tolerance. If this is the case, cyclosporine must not affect antigen priming or recognition. Two patients in our center underwent allogeneic spleen transplant in conjunction with renal and pancreatic transplant. Both patients were treated with therapeutic levels of cyclosporine during the course of transplant. Neither developed any clinical signs of renal or pancreatic transplant rejection. Both patients developed graft-versus-host disease and eventually required allogeneic (donor) splenectomy. Studies performed on the splenocytes recovered from these specimens demonstrate alloantigen-specific cytotoxic T cell precursors. These studies demonstrate that although cyclosporine can prevent allograft rejection it does not necessarily prevent or ameliorate graft-versus-host disease. Furthermore, cyclosporine does not prevent in vivo T cell priming of alloantigen recognition. The primed cytotoxic precursors can be expanded in the presence of exogenous interleukin-2 to become fully active cytoxic cells.

Alpha-fetoprotein (AFP) was purified from rat hepatoma sera and pooled human cord sera. Both AFP-rich fractions prepared by consecutive ion exchange and gel filtration chromatography and pure rat AFP prepared by liquid phase immunoabsorption lacked in vitro suppressive activity. Human AFP purified by affinity chromatography was suppressive, but so was similarly purified human cord albumin. Alteration of ionic conditions was shown to affect the activity of both human AFP and cord albumin. The primary mixed lymphocyte response, the generation of the secondary response, and the memory cell, per se, were all found to be sensitive to active human AFP under the appropriate culture conditions.

In a 2-year trial at a single center, prospective HLA-DR matching for cadaver renal transplantation exerted a stronger effect than either HLA-A and B matching or blood transfusion. One-year cumulative graft survivals for two-DR-matched organs was 92%. Grafts matched for one DR antigen had a cumulative 1-year graft survival of 65% whereas grafts matched for zero DR antigens had a cumulative 1-year survival of 41%. When all cadavers with less than two identifiable DR antigens were excluded from this analysis, however, the graft survivals of the groups known to be mismatched for one or two DR antigens were similar (61% versus 59%). Grafts matched for three or four HLA-A and B antigens did somewhat better than those matched for only zero, one, or two HLA A and B antigens (74% versus 59%, 1-year survival). This effect was only demonstrable in the zero- and one-DR-matched group. Similarly, prior blood transfusion exerted a modest effect (transfused versus nontransfused, 71% versus 56% 1-year graft survival) that was also most evident in the zero- and one-DR-matched groups. The institution of this trial was also associated with a 35% annual increase in the rate of transplantation and a 50% reduction in median patient waiting time. DR typing of cadaveric donors is feasible and highly desirable. Multicenter pooling of DR-typed donors is thus predicted to lead to optimal matching for a high proportion of renal transplant candidates.

The microcytotoxicity assay technique has been extensively refined to permit the use of granulocytes as target cells in an effort to identify neutrophil-specific antigens. Virtually every aspect of the test required revision to obtain clear, reproducible results. The most radical modification was the adoption of double-fluorescent vital staining to detect cytotoxicity. The reactions detected with this new assay did not correlate with defined human histocompatibility systems (e.g., HLA, ABH, NA, NB, NC), nor were the target antigens detected on lymphocytes or platelets. Cytotoxicity was highly specific and was produced by the immunoglobulin fraction of alloantisera only in the presence of complement, thus implicating an antigen-antibody phenomenon rather than variable viability of the ephemeral PMN's in vitro. These specificities may have an impact on some aspects of human transplantation (especially of bone marrow) as well as playing a role in some febrile transfusion reactions. Of perhaps greater import is the suggested role of the antigens in immunoneutropenias and therefore in the response of myelosuppressed patients to adjunctive leukocyte transfusion therapy.

Nosocomial pneumonia caused by Legionella pneumophila serogroup 1 occurred in five patients after bone marrow transplantation for hematologic malignancies. Two patients died as a result of the infection despite treatment with erythromycin. Serologic screening revealed no other cases of Legionnaires' disease in 40 consecutive recipients of bone marrow transplants, giving a frequency of infection of 13 percent. These five cases represent 23 percent of the pneumonia occurring in this group of patients. Patients undergoing bone marrow transplantation are highly susceptible to infectious complications. Legionnaires' disease must now be added to the list of pathogens infecting this group of patients. Erythromycin is not generally a part of standard empiric antibiotic regimens in febrile neutropenic patients, but appears to be a reasonable addition when pneumonia does not respond to conventional, empiric treatment. Even with appropriate therapy, Legionnaires' disease remains a highly lethal infection in immunocompromised hosts.

We have employed three different models of major histocompatibility complex (MHC) antigen to investigate the role of these antigens in some aspects of human T cell activation in in vitro; specifically the induction of lymphokine synthesis and receptors, and in antigen presentation. Those models were (1) allogeneic platelets (class I alone); (2) D/DR compatible lymphocytes (class I plus nonimmunogenic class II); and (3) allogeneic heat-treated lymphocytes. After heating at 45 C for 1 hr, the latter are completely viable and express both class I (HLA A and B) and class II (HLA, DR, MT/MB) MHC antigens but do not stimulate in the mixed lymphocyte reaction (MLR). These models were compared with conventional irradiated MLR stimulating or antigen-presenting cells. Only the conventional cells were able to stimulate the synthesis of interleukin-1 and interleukin-2. Also, irradiated but not heat-treated non-T cells could present soluble antigen to autologous T cells. This implies that intact and unmodified Ia molecules are required for those responses. On the other hand, heat treated allogeneic lymphocytes and D/DR-compatible lymphocytes but not allogeneic platelets could induce responsiveness to interleukin-2. This function appears to require a heat stable but nonallogeneic component of the class II molecules. Our previous observations employing these models have also shown that there is yet a third category of T cell responses, including memory cell priming and suppressor cell induction, that can occur in the presence of predominantly class I antigen. Taken together, these data illustrate the functional heterogeneity of T cell responses to Ia-like antigens. The possible relevance of these findings to clinical transplantation is discussed.

In these investigations, human lymphocytes primed in vitro in MLR have been employed as a model for human memory cells and have been compared to naive lymphocytes from the same donor. Both the stimulatory requirements and the regulation of these cells were found to differ significantly. The dose of stimulators giving a maximal primary (I) response was less than 10% the dose of restimulating cells giving a maximal secondary (II) response. II responses were further found to be inversely related to the original I response. This was associated with at least two separate regulatory phenomena. Suppressor cell induction was enhanced at high priming doses while memory cell precursors were preferentially stimulated at very low priming doses. Priming of memory cells could also be demonstrated to occur in the absence of any detectable I proliferation by utilizing platelets or heat treated stimulators. Memory cells were also a much more resistant than naive cells to both alloantigen induced suppressor cells and to culture activated monocyte suppressor cells. This in vitro model suggests that the human I and II responses to alloantigen have both distinct triggering requirements and differential sensitivity to regulatory cells. It is suggested that preferential formation of memory cells under conditions that require no proliferation and which are suboptimal for suppressor cell generation and the acquired resistance of memory cells to down regulation by suppressor cells may contribute to the poor graft prognosis of sensitized renal transplant patients.

The anamnestic response by human bi-directional (BD) mixed lymphocyte cultures (MLC) to restimulation by cells of the original stimulating type is generally strikingly reduced as compared to that of standard one-way cultures. This difference was shown not to be related to a change in kinetics nor was it due to exhaustion of the media or soluble factors since fresh media did not ameliorate the effect nor were supernatants from BD cultures found to be suppressive. The relative inhibition was also not reversed by removal of the allogeneic cells by phenotype specific antiserum. Cytotoxic tests with donor and responder specific antisera revealed that the cells bearing that phenotype were dramatically reduced in BD as compared to one-way cultures. Thus, the diminished secondary response appears to be due to cytotoxic elimination of the responder cells. This allogeneic cytotoxicity is dependent on non-T, phagocytic, adherent cells. The phenomenon is called Functional Cell Mediated Lympholysis (F-CML).

Heat-treated monocytes (1 hr, 45 degrees C) cannot present soluble antigen or mitogen to purified autologous T cells. This is despite normal viability and normal expression of class II MHC antigens. They do not secrete IL-1 nor stimulate secretion of IL-2 by T cells. Addition of exogenous IL-1 or IL-2 does not, however, reconstitute the response to soluble antigen. Furthermore, even after overnight pulsing with antigen prior to heat treatment under circumstances in which the antigen is known to be appropriately processed, stimulation of T-cell proliferation still does not occur. Thus there appear to be at least two discrete lesions produced by heating: failure of IL-1 production, per se, and intrinsic failure to present previously processed antigen. It is also hypothesized that heat treatment may produce alterations in Ia molecules which specifically disallow transduction of the proliferation signal to T cells.

Human monocytes cultured in monolayer for 6 days were found to secrete a factor that suppressed the T cell proliferative response to soluble Ag and to alloantigens. The elaboration of this monocyte suppressor factor (MSF) was not inhibited by indomethacin. It has an apparent Mr of 50 to 60 kDa. It does not inhibit soluble IL-1 in the murine thymocyte costimulator assay but does inhibit the activity of membrane bound IL-1, which we observed to be almost exclusively IL-1 alpha. MSF contains elevated amounts of plasminogen activator inhibitor (PAI) when measured either as bioactivity or in an ELISA. Its immunosuppressive properties are inhibited by anti-PAI antibody. Furthermore, the eluate but not the effluent of an anti-PAI immunoabsorbent column contains all of the immunosuppressive activity. Based on these data we suggest that MSF is, in fact, PAI and postulate that the mechanism of action is inhibition of the plasmin cascade, thereby preventing the release of membrane bound IL-1. This suggests that monocytes possess an autoregulatory circuit that may have implications for the kinetics of the inflammatory response.

The purpose of this retrospective analysis of DR-incompatible cadaver renal transplantation was to evaluate the effect of HLA A and B matching and blood transfusion status on actual one-year graft survival. There were 31 2-DR, 111 1-DR, and 27 0-DR grafts at risk during the study period. First, a comparison was made between preoperative (PRE) and peroperative (PER) transfusions alone. Graft survivals were 70% vs. 92% (2 DR), 67% vs. 52% (1 DR) and 71% vs. 39% (0 DR) for the PRE and PER groups, respectively. Statistical significance was not found between the two values in each DR subgroup, although the difference approached significance in the O DR group (0.1 greater than P greater than 0.05). Matching for greater than or equal to 2 A and B antigens significantly improved graft survival in the 1 DR-matched group when compared with those matched for less than 2 antigens (76% vs. 44%, P less than 0.005). While marked differences between the greater than or equal to 2 and less than 2 A and B matched groups were observed for both the 2 DR (92% vs. 68%, P greater than 0.1) and O DR groups (59% vs. 40%, P greater than 0.3) these differences were not significant. Stratifying the data for transfusion status revealed that the positive influence of HLA A and B matching in the 1 DR group was dependent upon the presence of preoperative blood administration. Graft survival of 87% for the PRE transfused recipients of grafts matched for greater than or equal to 2 A and B antigens was significantly better (P less than 0.001) than the 42% survival observed in similarly transfused recipients of poorer matched organs. Conversely, A and B matching was not significantly beneficial in the 1 DR recipients transfused only at the time of transplant with graft survivals of 57% vs. 43% for those matched for greater than or equal to 2 or less than 2 A and B antigens, respectively (P greater than 0.3). This analysis suggests that a combined effect of both HLA A and B matching and preoperative blood transfusions may allow for highly successful first cadaver renal transplantation in the face of DR incompatibility.

Analysis of retrospective data, obtained on 216 patients from 27 centers transplanted across some form of positive lymphocyte cross-match in a noncurrent serum, revealed that actuarial 1-yr graft survival was 69% in first transplants and 53% in recipients of second or subsequent transplants. Graft outcome did not correlate with peak antibody levels, change in antibody from peak to current, remoteness in time of the most recent positive serum, the number or timing of sera cross-matched, the technique or target cell cross-matched, or the degree of positivity of the most recent positive serum. Although a concurrent control population was not available, these results support the concept that acceptable graft survival can be achieved despite a positive cross-match with noncurrent sera.