Table 1.

Osteoclast Activity is Greater in IL-1 or TNF Receptor-Deficient Mice Compared to Normal Mice

Group	Distribution of osteoclasts in lacunae			Osteoclast activity score
	Shallow lacunae	Moderate lacunae	Deep lacunae
Wild type	3.00	0.11	0.00	3.30 ± 0.40
TNFRp55−/−-p75−/−	3.90	0.70	0.10	5.64 ± 0.92
IL-1RI−/−	2.91	1.45	0.27	6.60 ± 1.41
TNFRp55−/−-IL-1RI−/−	4.56	2.56	1.88	15.60 ± 2.32*

Seven days after bacterial inoculation, osteoclast activity was assessed in TRAP-stained sections at ×400 magnification by evaluating the relative depth of Howship’s lacunae for each osteoclast, i.e. the number of osteoclasts were counted and categorized as to their distribution in shallow, moderate, and deep lacunae. The relative size of each Howship’s lacunae was given a numerical value as follows: 1, shallow lacunae; 2, moderate lacunae (less than a half-width of the osteoclast); 3, deep lacunae (more than a half-width of the osteoclast). The osteoclast activity score for each group was obtained by taking the sum of the product of the number of osteoclasts in each category times the value of that category, which is presented as the mean ± SEM, n = 5, for each data point.

* Significantly larger osteoclast activity score was noted in TNFRp55^−/−-IL-1RI^−/− mice compared to the other three groups (P < 0.01).