Lymphatic routes

This approach can be used only for fat-soluble compounds that follow the same lymphatic route to be transported to the liver as carotenoids. The bioavailability of the compound of interest is determined by monitoring the appearance of the compound and its newly formed intestinal metabolites in the postprandial chylomicron fraction of plasma [also called the density < 1.006 kg/L fraction or triglyceride-rich lipoprotein (TRL) fraction because it is generally a mixture of chylomicrons (CMs) and very low density lipoproteins (VLDLs)] as a function of the time after ingestion. 

The portal blood-borne alkaline phosphatase from the intestine undergoes mixing in the liver with the enzyme that has traveled the lymphatic route. The proportions of these two populations of enzyme molecules, and their heat lability and sensitivity to L-phenylalanine are under the control of a number of physiological variables already discussed. 

Lymph node staging and mapping of lymphatic routes by examination of the sentinel lymph nodes using a RT-PCR-based method found to be a better predictor of possible recurrence of various tumors and fundamental for the success of the therapy. Molecular screening of sentinel lymph nodes is now frequently used for the staging of some tumors like melanoma and breast cancer. 

Bocci, V., Muscettola, M., Grasso, G., Magyar, Z., Naldini, A., and Szabo, G., The lymphatic route. 1. Albumin and hyaluronidase modify the normal distribution of interferon in lymph and plasma, Experientia., 1986 (April 15), 42(4), 432 33. 

Pessina, G.P., Bocci, V., Carraro, E, Naldini, A., and Paulesu, L., The lymphatic route. IX. Distribution of recombinant interferon-a 2 administered subcutaneously with oede-matogenic drugs, Physiol. Res., 1993, 42, 243-250. 

Although it has been clearly demonstrated that under normal physiological conditions retinol absorption occurs mainly via the lymphatic route (see above Fidge et al., 1968), the existence of an alternative route for retinol absorption has been suggested both by experimental studies in the rat and by features of the genetic disease abetalipoproteinemia in man. Information available suggests that under abnormal conditions retinol may be able to be absorbed via a nonlymphatic pathway and in a biochemical form other than the chylomicron in amounts sufficient to meet nutritional requirements for vitamin A. 

Histologically, LIP exhibits a diffuse and densely cellular interstitial inflammatory infiltrate that markedly expands and distorts the alveolar septa (44,50,55). The inflammatory infiltrate consists mostly of small, mature lymphocytes, macrophages, and plasma cells (Fig. 6). LIP may also contain reactive lymphoid follicles along airways and lymphatic routes as well as occasional small, poorly formed, nonnecrotizing granulomas with or without multinucleated... 

The reactive pulmonary lymphoid lesions are a group of inflammatory processes of diverse etiology characterized by the accumulation of numerous lymphocytes (as well as other chronic inflammatory cells such as plasma cells) within the lung. Often the lymphoid aggregates appear with germinal centers and proliferate along lymphatic routes or vessels. These lesions must be distinguished from lymphomas. 

Angioimmunoblastic lymphadenopathy (AIBL) can involve the lung in the form of diffuse interstitial infiltrates. Typically, there is little difficulty in distinguishing AIBL from LIP since AIBL has a distinctive set of clinical features, including generalized lymphadenopathy, hepatosplenomegaly, Coombs-positive hemolytic anemia, and skin rash. Microscopically, AIBL is polymorphous but includes numerous atypical immunoblasts as well as lymphocytes and plasma cells. The cellular infiltrate also predominantly involves lymphatic routes (around airways and vessels), rather than the interstitial compartment, as in the case of LIP (69). 

Bocci V, Muscettola M and Naldini A (1986). The lymphatic route-III. Pharmacokinetics of human natural interferon-beta injected with albumin as a retarder in rabbits. General Pharmacology, 17 445-9. 

Bocci V, Pessina GP, Nicoletti C et al. (1990). The lymphatic route-VII. Distribution of recombinant human interleukin-2 in rabbit plasma and lymph. Journal of Biological Regulation and Homeostatic Agents, 4 25-3. 

Absorption of the fat-soluble vitamins A, D, E and K all exhibit significant, if not total, absorption via the lymphatic route. Some lipophilic drugs also enter by this route, at a rate dependent on the availability of lipid. Note that the lymphatic S5 tem avoids the first-pass effect. The lymph vessels, in contrast to the blood vessels (where arteries and veins form a circuit), begin from blind vessels from the central lacteals of the villi. 

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