Transport of Viral-Size Particulate Matter after Intravenous versus Intralymphatic Entry

Peripheral lymphovenous communication in lymphoedema

AIM

To investigate whether in lower extremity lymphoedema, lymph proteins enter blood before they do the thoracic duct.

METHODS

Retrospective analysis of routine lymphoscintigraphy in 69 adults imaged at 5, 45 and 150 min following bilateral subcutaneous web space injection of Tc-nanocolloid was carried out. Regions of interest were placed over the liver and ilioinguinal lymph nodes bilaterally on the anterior images at 45 and 150 min. Individual minor (0.5 point for each) and major (1 point for each) criteria of abnormal scintigraphy were applied to each limb and summed to give a lymphoscintigraphic abnormality score. An abnormal limb had a score ≥1.

RESULTS

The ratio of hepatic counts per pixel to total bilateral ilioinguinal counts (L/N ratio) was higher in patients with abnormal results on lymphoscintigraphy (median 6.2; interquartile range 4.0-15.6 pixels×10; n=48) compared with that in patients with normal lymphoscintigraphic results (2.5 [1.5-5.0] pixels×10; n=21; P<0.0002). In the abnormal group, the lymphoscintigraphic score (two limbs summed) correlated with the 150-min L/N ratio (r s=0.42; P<0.005). L/N ratios at 45 and 150 min correlated in the abnormal group (r s=0.44; P<0.005) but not in the normal group (r s=0.3; P>0.05). The 45-min activity, as a percentage of the 150-min activity, was higher in lymph nodes than in the liver in both the abnormal (35.0 [8.2-50.0] vs. 10.6 [5.8-30.0]%; P<0.0001]) and normal groups (38.3 [18.4-63.5] vs. 23.3 [12.4-33.1]%; P<0.05), and, with respect to the liver, was higher in the normal group (P<0.01).

CONCLUSION

In lymphoedema, more lymph proteins enter blood proximal to the thoracic duct. The time courses of nodal and hepatic activities suggest that access may occur within nodes themselves.

Delivery of radiolabelled blood cells to lymphatic vessels by intradermal injection: a means of investigating lymphovenous communications in the upper limb

OBJECTIVE

To identify peripheral lymphovenous communications (LVCs) using labelled erythrocytes and intradermal injection. Intradermal injection delivers macromolecules to loco-regional lymph nodes faster than subcutaneous injection, suggesting easier lymphatic vessel access.

METHODS

Autologous erythrocytes labelled with 111In and 99mTc were injected into opposite hands. In four normal volunteers, the differentially labelled cells were given by intradermal injection on one side and subcutaneous injection on the other while in four breast cancer patients they were given by intradermal injection bilaterally 3 months after axillary lymph node clearance surgery. The axillae were imaged and blood samples obtained bilaterally at approximately 15, 30, 60, 120 and 180 min post-injection. Plasma activity was subtracted from whole blood activity to obtain erythrocyte-bound activity and contralateral concentrations were subtracted from ipsilateral concentrations to correct for ipsilateral recirculation. From estimated blood volume, erythrocyte and plasma activities contralateral to the injected side were calculated as percentage administered activity. Tracer concentrations in ipsilateral samples (%/l) were integrated to give total percentage administered activity, assuming a forearm blood flow of 20 ml/min.

RESULTS

Kinetics of plasma activity were consistent with small diffusible 99mTc complexes and protein-bound 111In. With both radionuclides, axillary nodes were visualized after intradermal but not subcutaneous injection, suggesting that nodal activity arises from erythrocytes. In one patient, 99mTc and 111In labelled erythrocytes accumulated in similar amounts ipsilaterally and contralaterally, suggesting bilateral LVCs distal to the ipsilateral sampling point. There was no evidence of LVCs in the other seven volunteers.

CONCLUSION

Intradermally injected erythrocytes are able to detect and potentially quantify peripheral LVCs.

Short-term effects of axillary lymph node clearance surgery on lymphatic physiology of the arm in breast cancer

It is not known why some women develop breast cancer-related lymphedema (BCRL) of the arm, whereas others having similar treatment do not. We speculated that increased uptake of protein into local blood may protect against BCRL. Sixteen women were given bilateral subcutaneous hand webspace injections of polyclonal immunoglobulin (HIgG), (99m)Tc-HIgG on one side and (111)In-HIgG on the other, before and 3 mo after axillary clearance surgery. The rates of clearance of activity from the depot (k) and accumulation in central blood (b(contra)) were measured using a scintillation probe and bilateral antecubital vein blood sampling, respectively. Activity accumulating in blood ipsilateral to the injected side, in excess of central blood activity (b(ipsi)) was also calculated as a measure of local vascular uptake. The k correlated with b(contra), but neither changed in response to surgery. However, b(ipsi) for injections of (99m)Tc-HIgG into the affected arm increased in all seven patients in whom data were available (0.018 +/- 0.006 to 0.038 +/- 0.007%/min; P < 0.05); indeed, in five of these seven, b(ipsi) paradoxically exceeded b(contra), and none developed BCRL at 3-yr follow-up. We conclude that uptake of protein into local blood and/or proteolysis increases after axillary surgery and may protect against BCRL.

Propagation and dissemination of infection after vaginal transmission of simian immunodeficiency virus

In the current global AIDS pandemic, more than half of new human immunodeficiency virus type 1 (HIV-1) infections are acquired by women through intravaginal HIV exposure. For this study, we explored pathogenesis issues relevant to the development of effective vaccines to prevent infection by this route, using an animal model in which female rhesus macaques were exposed intravaginally to a high dose of simian immunodeficiency virus (SIV). We examined in detail the events that transpire from hours to a few days after intravaginal SIV exposure through week 4 to provide a framework for understanding the propagation, dissemination, and establishment of infection in lymphatic tissues (LTs) during the acute stage of infection. We show that the mucosal barrier greatly limits the infection of cervicovaginal tissues, and thus the initial founder populations of infected cells are small. While there was evidence of rapid dissemination to distal sites, we also show that continuous seeding from an expanding source of production at the portal of entry is likely critical for the later establishment of a productive infection throughout the systemic LTs. The initially small founder populations and dependence on continuous seeding to establish a productive infection in systemic LTs define a small window of maximum vulnerability for the virus in which there is an opportunity for the host, vaccines, or other interventions to prevent or control infection.