In vivo trafficking, persistence and efficacy of Lewis-Y chimeric antigen receptor T cells in patients with Lewis-Y positive acute myeloid leukaemia (P4354)

Second generation chimeric antigen receptor (CAR) T cells were used to treat patients with acute myeloid leukemia (AML) in a phase I clinical study. Autologous T cells were genetically modified to express a CAR which re-directed T cell effector function to the LeY tumor associated carbohydrate antigen on AML cells. CAR-T cell therapy safety, AML disease response, and CAR-T cell trafficking and persistence post-infusion were investigated. Five patients received GMP grade CAR-T cells (LeY-T). Post infusion, no patients experienced grade 3 or 4 toxicities. Patient AML responses to LeY-T cell infusion included a transient cytogenetic response and a reduction in peripheral blood leukemic blast count. In all patients, LeY-T cells trafficked thru peripheral blood, and persisted in the bone marrow. In one patient, leukemia cutis was associated with trafficking of the LeY-T cells to the skin at sites of AML blast infiltration. Despite LeY-T cells being present at the disease site, relapse with LeY-expressing AML blasts occurred in all patients (range 29 days to 23 months) post-infusion. Further studies indicated LeY-T cell CAR expression was downregulated post-infusion in vivo, this was also observed post-LeY antigen exposure and long term culture in vitro. This study provides important safety and feasibility data to support the application of CAR-T cell therapy to treat AML. Furthermore, we provide a potential mechanism for tumor escape from LeY-T cell surveillance in vivo.

Phase I pharmacokinetic (PK) and pharmacodynamic (PD) study of LBH589, a novel deacetylase (DAC) inhibitor given intravenously on a new once weekly schedule

14019

Background: LBH589 is a novel deacetylase inhibitor that inhibits proliferation of tumor cells at nanomolar levels. This phase I study tested the safety and tolerability of IV LBH589 once each week for 3 of 4 wks in pts with advanced solid tumors or lymphoma. Methods: LBH589 was administered IV over 30 min. on days 1, 8 and 15 of a 28-day cycle. Western blots on peripheral blood lymphocytes were used to study histone acetylation (HA). Plasma PK profiles were analyzed on Days 1 and 8. Results: Thirty five pts (median age: 70 yrs; 23M, 12F) have been treated on 3 dose levels [10 mg/m2 (8pts), 15 mg/m2 (8 pts), 20 mg/m2 (19 pts)] with the following tumor types: Cutaneous and peripheral T cell lymphoma (7 pts), prostate (6 pts), mesothelioma (4 pts), colon (3 pts) and other (15 pts). There was one dose-limiting toxicity (transient grade 4 thrombocytopenia) at 20 mg/m2, none at the lower doses. Other G3/G4 toxicities (all cycles) include: transient thrombocytopenia (G4–5 pts, G3–5 pts), neutropenia (G3–2 pts), anemia (G3–5 pts), G3 hypophosphatemia (1 pt), G3 hypokalemia (1 pt), G3 nausea (1 pt) and G3 pruritus (1 pt). Thrombocytopenia was transient. Of 2,042 ECGs, 1 pt had an increase in QTcF from baseline of > 60 msec another with a QTcF >500 msec, both at 20 mg/m2. There was a dose-dependent increase in HA 7 days after one dose with 43% (10 mg/m2), 50% (15 mg/m2) and 60% (20 mg/m2) of pts with increased acetylation. The LBH589 plasma conc. peaked at the end of the 0.5 hr infusion with a mean terminal half-life of 16 hr. Median Cmax achieved with 20 mg/m2 was 1,000 ng/mL (2.86 μM). The AUC0-inf increased linearly with IV doses of 10–20 mg/m2. One pt with CTCL achieved a complete response (CR) on cycle 3, Day 1; this pt had previously received oral LBH589 at 20 mg MWF, achieving a CR on cycle 6, Day 28 that lasted for 7 months. One peripheral T-Cell lymphoma pt achieved a partial response that has persisted for >7 months. One pt with prostate cancer has had a 26% reduction in nodal disease and > 50% drop in PSA in the first 2 cycles. Conclusions: The maximum tolerated dose of LBH589 given IV wkly on a 3 of 4 wk schedule is 20 mg/m2. This dose produced sustained PD effects and higher systemic exposure compared to oral LBH589. Preliminary evidence of antitumor activity has been observed.

No significant financial relationships to disclose.

Imagery rehearsal therapy for chronic nightmares in sexual assault survivors with posttraumatic stress disorder: a randomized controlled trial

CONTEXT

Chronic nightmares occur frequently in patients with posttraumatic stress disorder (PTSD) but are not usually a primary target of treatment.

OBJECTIVE

To determine if treating chronic nightmares with imagery rehearsal therapy (IRT) reduces the frequency of disturbing dreams, improves sleep quality, and decreases PTSD symptom severity.

DESIGN, SETTING, AND PARTICIPANTS

Randomized controlled trial conducted from 1995 to 1999 among 168 women in New Mexico; 95% had moderate-to-severe PTSD, 97% had experienced rape or other sexual assault, 77% reported life-threatening sexual assault, and 58% reported repeated exposure to sexual abuse in childhood or adolescence.

INTERVENTION

Participants were randomized to receive treatment (n = 88) or to the wait-list control group (n = 80). The treatment group received IRT in 3 sessions; controls received no additional intervention, but continued any ongoing treatment.

MAIN OUTCOME MEASURES

Scores on the Nightmare Frequency Questionnaire (NFQ), Pittsburgh Sleep Quality Index (PSQI), PTSD Symptom Scale (PSS), and Clinician-Administered PTSD Scale (CAPS) at 3- and 6-month follow-up.

RESULTS

A total of 114 participants completed follow-up at 3 and/or 6 months. Comparing baseline to follow-up (n = 97-114), treatment significantly reduced nights per week with nightmares (Cohen d = 1.24; P<.001) and number of nightmares per week (Cohen d = 0.85; P<.001) on the NFQ and improved sleep (on the PSQI, Cohen d = 0.67; P<.001) and PTSD symptoms (on the PSS, Cohen d = 1.00; P<.001 and on the CAPS, Cohen d = 1.53; P<.001). Control participants showed small, nonsignificant improvements for the same measures (mean Cohen d = 0.21). In a 3-point analysis (n = 66-77), improvements occurred in the treatment group at 3-month follow-up (treatment vs control group, Cohen d = 1.15 vs 0.07 for nights per week with nightmares; 0.95 vs -0.06 for nightmares per week; 0.77 vs 0.31 on the PSQI, and 1.06 vs 0.31 on the PSS) and were sustained without further intervention or contact between 3 and 6 months. An intent-to-treat analysis (n = 168) confirmed significant differences between treatment and control groups for nightmares, sleep, and PTSD (all P<.02) with moderate effect sizes for treatment (mean Cohen d = 0.60) and small effect sizes for controls (mean Cohen d = 0.14). Posttraumatic stress symptoms decreased by at least 1 level of clinical severity in 65% of the treatment group compared with symptoms worsening or not changing in 69% of controls (chi(2)(1) = 12.80; P<.001).

CONCLUSIONS

Imagery rehearsal therapy is a brief, well-tolerated treatment that appears to decrease chronic nightmares, improve sleep quality, and decrease PTSD symptom severity.

Prevalence of asthma and other respiratory symptoms in children living near and away from opencast coal mining sites

BACKGROUND

Public concern about respiratory conditions prompted the investigation of asthma and other respiratory diseases in children living near and away from opencast coal mining sites.

METHODS

We selected all 4860 children aged 1--11 years from five socioeconomically matched pairs of communities close to (OC) and away from (CC) active opencast sites. A postal questionnaire collected data on health and lifestyle. Outcomes were the cumulative and period prevalence (2 and 12 months) of wheeze, asthma, bronchitis and other respiratory symptoms.

RESULTS

The cumulative prevalence of wheeze varied from 30% to 40% across the ten communities, it was 36% in OC and 37% in CC. The cumulative prevalence of asthma was 22% in both OC and CC, varying between 12% and 24%. We found little evidence for associations between living near an opencast site and an increased prevalence of respiratory illnesses, or asthma severity. Some outcomes such as allergies, hayfever, or cough varied little across the study communities. Others, such as the use of asthma medication, the number of severe wheezing attacks in the past year or tonsillitis showed large variation. These similarities and variations were not explained by differences in lifestyle factors or differences in health services delivery and remain unexplained.

CONCLUSIONS

There was little evidence of an association between residential proximity to opencast mining sites and cumulative or period prevalence of respiratory illness, or asthma severity. Some variations in health outcomes between communities remained unexplained.

Surgical treatment for rheumatoid neck arthritis bilateral occipitospinal fusion with plate fixation

The results of surgical treatment of 12 patients with rheumatoid cervical spine arthritis were reviewed. The Ranawat classification was as follows: 5 with Ranawat IIIB, 1 Ranawat IIIA and 6 Ranawat II. Decompression and fusion using autogenous iliac bone graft and double occipitospinal plate fixation was carried out on 11 of these patients; the remaining patient underwent upper cervical spine fusion using screw and wire fixation. The main indication for surgery was neurological deterioration. In three cases previous surgery had been carried out on the cervical spine. The results were assessed at a mean follow-up of 26.1 months. According to Frankel's grading the neurological recovery in patients with neurological compression was one grade. There was clinical and radiological evidence of fusion in all these patients. The following complications required further surgery: acute postoperative epidural hematoma (one patient) screw loosening (one patient)

CONCLUSION

Fusion of the occiput and lateral mass of the involved cervical spine using a plate on each side provides a relatively stable fixation in patients with rheumatoid arthritis of the cervical spine. Laminectomy and adequate decompression of the neural elements can be carried out without compromising spinal stability. There is a relatively high complication rate associated with surgery for rheumatoid neck and the patient needs to be informed.

Choice of conditional models in bivariate survival

We consider bivariate survival problems in which interest is in the conditional distribution of one survival variable given an uncensored observation of the other. The work is motivated by an analysis of time to cancer diagnosis then subsequent survival amongst a group of organ transplant recipients. The effect of conditioning is illustrated for five standard bivariate models. The consequences of adopting a misspecified marginal approach in which the conditioning variable is considered to be a fixed covariate are investigated.

In vivo cellular tropism of human T-lymphotropic virus type II is not restricted to CD8+ cells

We have examined the in vivo and in vitro susceptibility of lymphocyte subpopulations to human T-lymphotropic virus type II (HTLV-II) to determine the cellular tropism for this virus. Monoclonal antibodies to T-cell subsets were used to separate highly purified CD4+ and CD8+ cells from peripheral blood lymphocytes of 35 individuals previously shown to be infected with HTLV-II. The purified T-cell subsets were analyzed for HTLV-II provirus (pol and tax gene sequences) by polymerase chain reaction (PCR) and cultured to determine virus expression by p24gag antigen detection. On the basis of PCR amplification in the pol and tax gene regions, both CD8+ subsets (89 to 91%) and CD4+ subsets (54 to 80%) from most infected subjects demonstrated HTLV-II provirus, irrespective of the viral genotype. Analysis of cultured lymphocytes demonstrated a higher spontaneous lymphocyte proliferation (17,986 +/- 4675 cpm) and p24gag antigen production (median 115 pg/ml; range 14-1360 pg/ml) in CD8+ cells compared to CD4+ cells (2333 +/- 826 cpm; p24gag antigen; 9 pg/ml; 2-250 pg/ml), suggesting a higher proviral load in CD8 cells. Limiting cell-dilution PCR analysis indicated that the CD8+ subset carried a higher HTLV-II provirus burden than the CD4+ subset. In vitro infection of purified CD4+ and CD8+ lymphocytes with irradiated HTLV-II cell lines resulted in productive infection of both subsets. Cell sorting and PCR analysis of lymphocyte subsets from 4 HTLV-II-infected subjects further demonstrated that in addition to CD4+ and CD8+ subsets, both CD45RO+ and CD45RO- and non-T-cells (CD14, CD16, and CD19) carried HTLV-II provirus. Taken together, these data suggest that HTLV-II possesses a broad tropism for peripheral blood mononuclear cells.

Rapid enzymatic analysis for human immunodeficiency virus type 1 DNA in clinical specimens

A clinical procedure for rapid detection of human immunodeficiency virus type 1 (HIV-1) by DNA amplification is demonstrated. The rapid procedure reduces handling requirements and amplification time and eliminates use of radioactivity for the detection of the amplification product. Total leukocyte lysates are the amplification substrates. Two conserved regions in the HIV-1 genome are amplified by 45 cycles of a two-temperature thermal cycle and the amplification products are detected by ultraviolet light after electrophoresis on agarose gels. Twenty-four specimens clinically diagnosed by detection of antibody (IgG) to HIV-1 were confirmed by the rapid DNA amplification procedure. In a blind study, 56 samples positive for HIV-1 DNA were detected in 503 individuals by the current classical polymerase chain reaction method; the same 56 positive samples were also detected by the rapid amplification protocol. No false-positive or false-negative results were obtained. The turnaround time for analysis has been reduced to &lt; 24 h without compromising test results.

Rapid enzymatic analysis for human immunodeficiency virus type 1 DNA in clinical specimens

A clinical procedure for rapid detection of human immunodeficiency virus type 1 (HIV-1) by DNA amplification is demonstrated. The rapid procedure reduces handling requirements and amplification time and eliminates use of radioactivity for the detection of the amplification product. Total leukocyte lysates are the amplification substrates. Two conserved regions in the HIV-1 genome are amplified by 45 cycles of a two-temperature thermal cycle and the amplification products are detected by ultraviolet light after electrophoresis on agarose gels. Twenty-four specimens clinically diagnosed by detection of antibody (IgG) to HIV-1 were confirmed by the rapid DNA amplification procedure. In a blind study, 56 samples positive for HIV-1 DNA were detected in 503 individuals by the current classical polymerase chain reaction method; the same 56 positive samples were also detected by the rapid amplification protocol. No false-positive or false-negative results were obtained. The turnaround time for analysis has been reduced to < 24 h without compromising test results.

A Mycobacterium malmoense infection of the hand presenting as carpal tunnel syndrome

We report an atypical tuberculous infection by Mycobacterium Malmoense of the synovium of the flexor tendons at the wrist presenting as carpal tunnel syndrome. This is the first time this organism has been described in a site other than the lungs or the cervical lymph nodes.

The Small AO External Fixator in the Treament of Unstable Distal Forearm Fractures

Sixteen patients with severely comminuted displaced fractures of the distal radius and ulna, who were treated with a small AO external fixator, have been reviewed at an average of 2.2 years after injury.

Removal of the fixator, at an average of 4.9 weeks, was followed by significant alteration in position in some cases. The external fixator should be retained for eight weeks to reduce the risk of loss of position.

In those cases with a good or excellent anatomical result on radiological assessment after removal of the fixator, the functional results were good or excellent in 80%.

A Mycobacterium Malmoense Infection of the Hand Presenting as Carpal Tunnel Syndrome

We report an atypical tuberculous infection by Mycobacterium Malmoense of the synovium of the flexor tendons at the wrist presenting as carpal tunnel syndrome. This is the first time this organism has been described in a site other than the lungs or the cervical lymph nodes.

Is there a relationship between ambulatory intra-arterial blood pressure and left ventricular function?

The relationship between ambulatory intra-arterial blood pressure and left ventricular ejection fraction was examined in a group of 23 untreated hypertensive subjects who underwent concurrent radionuclide ventriculography. All patients had a normal ejection fraction at rest (range, 50-80%), and no significant correlation was found between blood pressure and resting ejection fraction. Sixty-one percent of patients failed to increase their ejection fraction by 5% on exercise; the mean daytime systolic pressure (168 +/- 15 mm Hg) was lower in this group than in those who had a normal exercise response (188 +/- 17 mm Hg; p less than 0.005). Thirty percent of patients had left ventricular hypertrophy based on electrocardiographic criteria; this group had a higher mean blood pressure (189 +/- 20 mm Hg) than the remainder (170 +/- 15 mm Hg; p less than 0.05). A closer correlation was demonstrated between blood pressure and ejection fraction response to exercise in the group with left ventricular hypertrophy (r = 0.8) than in the group without hypertrophy (r = 0.3). These results failed to demonstrate a linear relationship between blood pressure and ejection fraction. However, a relationship between the height of blood pressure and the development of left ventricular hypertrophy was shown, and myocardial response to exercise was increased in patients with left ventricular hypertrophy.

The pediatric nephrologist's dilemma: growth after renal transplantation and its interaction with age as a possible immunologic variable

Two important criteria for successful end-stage renal disease therapy in children are achievement of optimal growth and possession of a well-functioning renal transplant. We describe eight children with accelerated post-transplant growth. Accelerated and even catch-up growth was achievable if the transplant occurred at an early age (less than 9 years), the daily dose of prednisone was low (less than or equal to 0.24 mg/kg/d), and renal function was excellent (creatinine clearance greater than or equal to 89 mL/min/1.73 m2). However, the benefit to growth of transplanting a kidney in young children may be offset by reduced cadaver graft survival in children younger than 6 years. To study whether the less favorable graft survival was attributable to an increased immunologic responsiveness in the younger child, we examined three tests of nonspecific immune responsiveness, each of which, when increased, may indicate a propensity toward rejection: total T cell absolute number, T helper/suppressor ratio, and spontaneous blastogenesis. Each measurement was significantly increased in 20 uremic children 5 years old or younger, compared with 81 children 6 to 23 years of age. These data suggest that improved growth may be attained by transplanting a kidney in the young child with end-stage renal disease, but the young child may be at increased risk for rejection. This hypothesis suggests that for optimal rehabilitation, strategies should take into account the unique needs of the young child.

Once- and twice-daily bevantolol for systemic hypertension using 24-hour ambulatory intraarterial blood pressure recording

The antihypertensive efficacy of bevantolol, a selective beta 1-adrenoreceptor antagonist, was evaluated in 17 patients with essential hypertension, using continuous ambulatory intraarterial blood pressure (BP) monitoring. The study compared a twice-daily regimen (titrated dose of 200 to 600 mg/day) with the same amount given in a single daily dose. Within-patient comparisons of mean hourly systolic and diastolic BPs and heart rate showed a highly significant effect with twice-daily therapy (p less than 0.001) for all of the 24 hours. Similar significant results were obtained with a single morning dose. There was no difference between the pattern or extent of BP reduction with the 2 regimens. The decrease in BP after bevantolol persisted during the physiologic tests (rest, tilt, isometric and dynamic exercise). Four patients developed minor side effects with the single morning dose, and only 1 patient with the twice-daily regimen. These effects included tiredness, fatigue and dizziness. Unlike pure beta-blocking agents, bevantolol controlled the early morning increase in BP, lending support to the belief that it possesses vasodilatory properties in addition to beta blockade. These results suggest that bevantolol may be useful as first-line therapy in a once-daily dosage for the treatment of essential hypertension.

Effects of tiapamil, a new calcium channel blocker, on ambulatory intraarterial blood pressure and exercise-induced changes in blood pressure

The duration and magnitude of effect of a new calcium-channel blocker, tiapamil, given twice daily, was studied in 17 hypertensive patients using ambulatory intraarterial blood pressure recording. The drug produced moderate reductions of blood pressure throughout the 24-h cycle with slight reduction of effect before each dose. Ten patients reported side effects, and one withdrew as a result of these. Tiapamil attenuated the blood pressure rise during dynamic cycle ergometry but had no effect on the increase during isometric hand grip. We conclude that tiapamil is similar to existing calcium-channel blocking agents in lowering the blood pressure, but it does not appear to influence the response to isometric exercise in this dose.

Ambulatory blood pressure and assessment of pacemaker function

Ten patients in sinus rhythm with ventricular demand (VVI) pacemakers implanted for the sick sinus syndrome underwent 24 hour ambulatory blood pressure and electrocardiographic recording by a modified version of the Oxford system. Five patients had symptoms of dizziness or presyncope at the time of study and five were symptom free. The onset of pacing was associated with a fall in arterial blood pressure in both groups which was larger in the patients with symptoms, and in these patients the blood pressure recovery consequent on baroreflex activation was delayed by up to fifteen beats. In three of the patients with symptoms the original pacemaker was replaced by an atrioventricular pacing (DVI) device. This abolished symptoms and the initial fall and delayed recovery of blood pressure. Thus it appears that the development of symptoms of hypotension after the onset of ventricular pacing is determined by the rate of the baroreflex response. These symptoms and the haemodynamic consequences may be alleviated by dual chamber pacing.

Cellular and T-lymphocyte subpopulation profiles in bronchoalveolar lavage fluid from patients with acquired immunodeficiency syndrome and pneumonitis

The cellular composition and T-lymphocyte subpopulations of bronchoalveolar lavage (BAL) fluid from 12 patients with acquired immunodeficiency syndrome (AIDS) and active pneumonitis were examined. Differential cell counts were performed on BAL specimens from each patient and from 25 normal subjects. The BAL and peripheral blood (PB) lymphocytes were isolated from 8 patients and 11 subjects. Leu 4 (mature T), Leu 2 (T suppressor), and Leu 3 (T helper) markers were identified by fluorescein-labeled monoclonal antibody agents and counted in an automated flow cytometer. Infectious pneumonitis caused by Pneumocystis carinii and/or cytomegalovirus and/or Mycobacterium avium-intracellulare was diagnosed in all but 1 patient. All but 2 patients demonstrated lymphocytosis in the BAL fluid; only 3 had greater than 1% neutrophils. The BAL cell differentials were not predictive of the type of pneumonitis. The Leu 3/Leu 2 ratios were (mean +/- SEM): 0.08 +/- 0.03, patients' BAL fluid; 1.55 +/- 0.21, subjects' BAL fluid; 0.18 +/- 0.06, patients' PB; 1.42 +/- 0.12, subjects' PB. The marked decrease in Leu 3/Leu 2 ratios primarily reflected severely diminished proportions of Leu 3 positive cells (3 +/- 1.3% compared with a control value of 35 +/- 4.0%), although the proportion of Leu 2 positive cells tended to be elevated as well (46 +/- 7.9% compared with a control value of 22 +/- 2.2%). Bronchoalveolar lavage specimens from patients with AIDS and these types of pneumonitis may contain increased proportions of lymphocytes. The accumulation of lymphocytes, however, does not reflect homing of helper T-lymphocytes to the site of pulmonary infection.

Recombinant alpha-2 interferon therapy for Kaposi's sarcoma associated with the acquired immunodeficiency syndrome

In a randomized prospective study we tested the toxicity and efficacy of recombinant alpha-2 interferon in the treatment of Kaposi's sarcoma associated with the acquired immunodeficiency syndrome. High doses (50 X 10(6) U/m2 body surface area, intravenously) or low doses (1 X 10(6) U/m2, subcutaneously) of recombinant alpha-2 interferon were administered to 20 patients for 5 days/wk, every other week, for four treatment cycles. Therapy was well tolerated subjectively and caused only mild hematologic and hepatic toxicity at both dose levels. No consistent or sustained changes were seen in immunologic variables during or after treatment. Six patients with Kaposi's sarcoma, four at high dose and two at low dose, had objective responses (complete or partial) to treatment. However, therapy did not appear to eradicate cytomegalovirus carriage or prevent opportunistic infections related to cytomegalovirus.

Quantitative changes in T helper or T suppressor/cytotoxic lymphocyte subsets that distinguish acquired immune deficiency syndrome from other immune subset disorders

Quantitative measurements of the immune cell subgroups, T helper (Leu 3+/OKT4+) cells and T suppressor/cytotoxic (Leu 2+/OKT8+) cells, were made in patients having acquired immune deficiency syndrome (AIDS) with Kaposi's sarcoma and in patients with AIDS and opportunistic infection, as well as in three other relevant populations. These included patients with lymphadenopathy syndrome, e.g., homosexually active males with lymphadenopathy who sought medical care for additional symptoms, and healthy male homosexuals, as well as a control population. Decrease in the number of T helper cells is characteristic of AIDS with Kaposi's sarcoma or opportunistic infection. Augmentation of the T suppressor/cytotoxic cell population is rare in AIDS with Kaposi's sarcoma but is more frequent in AIDS with opportunistic infection. Augmentation of the T suppressor/cytotoxic cell population, however, may occur in a variety of circumstances, including cytomegalovirus and other viral infections, in healthy, homosexually active males, and in otherwise healthy hemophiliac subjects receiving factor VIII treatment. Reduced T helper:T suppressor/cytotoxic cell ratio can be caused by either decrease in the number of T helper cells or augmentation of the T suppressor/cytotoxic cell population. Lowered T helper:T suppressor/cytotoxic cell ratio does not, by itself, help to distinguish between AIDS and other causes of reduced ratios. Quantitative measurements are needed to define the T subset changes. AIDS is characterized by decrease in the number of T helper cells and reduced T helper:T suppressor/cytotoxic cell ratio. The T helper (Leu 3+) and T suppressor/cytotoxic (Leu 2+) cell subpopulations can change independently. Identification of decrease in the number of T helper cells as an alteration that occurs independently of numerical change in other lymphoid subpopulations, such as T suppressor/cytotoxic cells and B cells, and the close association of the decrease in the number of T helper cells with AIDS are consistent with a distinct pathogenesis (and cause) for AIDS.

Blood volume in the pregnant rabbit

Red cell and plasma volumes were measured using 51Cr-labelled red cells and 125I-labelled HSA respectively, in seventeen pregnant rabbits at 28-29 days of pregnancy, and fifteen non-pregnant rabbits weight-matched with the pregnancy rabbits before mating. Red cell volume in the pregnant group (20.0 +/- 2.8 ml . kg-1; mean +/- S.D.), was greater than in the control rabbits (18.0 +/- 2.0 ml . kg-1; P less than 0.05); plasma volumes (39.0 +/- 4.5 and 37.3 +/- 4.4 ml . kg-1 respectively) were not statistically different. Blood volume was derived from the sum of independently measured red cell and plasma volumes. That of the pregnant group (59.0 +/- 5.3 ml . kg-1) was just significantly greater than that of control rabbits (55.3 +/- 5.3 ml . kg-1; P less than 0.05). When the volume of distribution of the labels was corrected, by subtracting fetal weight from maternal body weight, the red cell, plasma and blood volumes were all significantly greater in the pregnant rabbits (P less than 0.02). Although the large vessel haematocrit of the pregnant group (41.6 +/- 4.4%) exceeded that of the non-pregnant group (38.7 +/- 2.6%; P less than 0.05), there was no significant difference in whole body haematocrit or Fcells (the ratio of the whole body to large vessel haematocrit) between the two group of rabbits.

Limited cleavage of human immunoglobulins by elastase of human neutrophil polymorphonuclear granulocytes. Possible modulator of immune complex disease

Human polymorphonuclear lysosomal granules contain a neutral protease which is capable of digesting human immunoglobulins. The protease is located in the azurophil granules and enzymatically cleaves IgG, producing a Fab-like piece which is recoverable. The Fc-like fragment is not crystallized. The Fab-like fragment competes effectively for ligands formed by native antibody from which the fragments were produced.