Two Characteristic Subsets

We set j = i(s ). Then s G Rj(l). Note also that 2 j. Thus, there exist elements l, . .., lj in L such that 

finally, that s G lj k+iq- Thus, there exists an element p in lj k+ such that s G pq. 

Recall that dL is our notation for the smallest element in S- L)). For the remainder of this section, we shall write d instead of d.  

Note that (L) is the disjoint union of the sets S i (/), SrXj(l), and Sj (/). Note also that 

We shall use this latter observation frequently without further mentioning. 

Since iri s ) = 1, Lemma 10.3.1 tells us also that s S-i l). Therefore, we must have s G Sq 1)- 

Corollary 10.4.4 Let s be an element in (L) such that d — I. Then the following hold. 

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COPD includes chronic bronchitis and emphysema. Chronic bronchitis is defined clinically as a chronic productive cough for at least 3 months in each of two consecutive years in a patient in whom other causes have been excluded.1 Emphysema is defined pathologically as the presence of permanent enlargement of the airspaces distal to the terminal bronchioles, accompanied by destruction of their walls without obvious fibrosis.1 The major risk factor for both conditions is cigarette smoking, and many patients share characteristics of each condition. Therefore, new consensus guidelines have moved away from using these subsets and instead focus on chronic airflow limitation. 

These chemokines have been further subdivided into two subsets, a and d- The a-chemokine genes are clustered on chromosome 4 and share a characteristic amino acid sequence such that the first two of their four cysteine groups are separated by one amino acid (C-X-C). Genes encoding the 3-chemokines are located on chromosome 17. These proteins have no intervening amino acid between the first two cysteine residues (C-C). 

In recent years it has become clear that the nature of the immune response initiated by CD4 T lymphocytes is at least partly dependent on the selection or preferential activation of particular subsets of CD4 T lymphocytes which secrete defined patterns of cytokines (Table 2.3). These patterns of cytokine release result in the initiation and propagation of distinct immune effector mechanisms. Initial studies of mouse CD4 T lymphocyte clones revealed that these could be divided into two basic fiinaional subsets termed ThI and Th2. ThI T lymphocytes were characterized by the predominant secretion of IL-2, interferon y (IFNy) and tumour necrosis factor 8 (TNF/3), while Th2 cells characteristically... 

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